Café au Lait Macule

• Seborrheic keratosis

• Multiple lentigines syndrome

• Lentigo

• Nevi

Calcification on Chest Radiograph

• Lung neoplasm (primary or metastatic)

• Silicosis

• Idiopathic pulmonary fibrosis

• Tuberculosis

• Histoplasmosis

• Disseminated varicella infection

• Mitral stenosis (end stage)

• Secondary hyperparathyroidism

Calcifications, Cutaneous

• Calcification, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia (CREST) syndrome

• Trauma

• Pancreatitis or pancreatic cancer

• Chronic renal failure

• Sarcoidosis

• Hyperparathyroidism

• Milk-alkali syndrome

• Hypervitaminosis D

• Panniculitis

• Idiopathic

• Iatrogenic (e.g., application of calcium alginate dressing to skin)

• Multiple myeloma

• Dermatomyositis

• Parasitic infections

• Leukemia

• Lymphoma

Calcium Stones

• Medications (e.g., antacids, loop diuretics, vitamin D, acetazolamide, glucocorticoids)

• Primary hyperparathyroidism

• Hypercalcemia from malignant disease

• Sarcoidosis

• Prolonged immobilization

• Hyperoxaluria (e.g., Crohn’s disease, celiac disease, chronic pancreatitis)

• Hyperuricosuria (e.g., hyperuricemia, excessive dietary purine, allopurinol, probenecid)

• Renal tubular acidosis

• Milk-alkali syndrome

• Thyrotoxicosis

• Hypocitraturia (e.g., metabolic acidosis, hypomagnesemia, hypokalemia)

Candidiasis

• Tinea

• Eczema

• Seborrheic dermatitis

• Psoriasis

• Cellulitis

Candidiasis, Vulvovaginal

• Bacterial vaginosis

• Trichomoniasis

Carbon Monoxide Poisoning

• Amphetamines and derivatives

• Cocaine

• Cyclic antidepressants

• PCP

• Phenothiazines

• Theophylline toxicity

Carcinoid Syndrome

• Idiopathic flushing

• Anxiety

• Menopause

• Hyperthyroidism

• Medications (e.g., niacin)

Cardiac Arrest, Nontraumatic ²⁷

• Cardiac (coronary artery disease, cardiomyopathies, structural abnormalities, valve dysfunction, arrhythmias)

• Respiratory (upper airway obstruction, hypoventilation, pulmonary embolism, asthma, COPD exacerbation, pulmonary edema)

• Circulatory (tension pneumothorax, pericardial tamponade, pulmonary embolism [PE], hemorrhage, sepsis)

• Electrolyte abnormalities (hypokalemia or hyperkalemia, hypomagnesemia or hypermagnesemia, hypocalcemia)

• Medications (tricyclic antidepressants, digoxin, theophylline, calcium channel blockers)

• Drug abuse (cocaine, heroin, amphetamines)

• Toxins (carbon monoxide, cyanide)

• Environmental (drowning/near-drowning, electrocution, lightning, hypothermia or hyperthermia, venomous snakes)

Cardiac Death, Sudden ¹

NONCARDIAC

• CNS hemorrhage

• Massive pulmonary embolus

• Drug overdose

• Hypoxia secondary to lung disease

• Aortic dissection or rupture

Cardiac Enlargement ¹⁵

CARDIAC CHAMBER ENLARGEMENT

• Chronic volume overload: mitral or aortic regurgitation, left-to-right shunt (patent ductus arteriosus [PDA], ventricular septal defect [VSD], arteriovenous [AV] fistula)

• Cardiomyopathy: ischemic, nonischemic

• Decompensated pressure overload: aortic stenosis, hypertension

• High-output states: severe anemia, thyrotoxicosis

• Bradycardia: severe sinus bradycardia, complete heart block

LEFT ATRIUM

• Left ventricular (LV) failure of any cause

• Mitral valve disease

• Myxoma

RIGHT VENTRICLE

• Chronic LV failure of any cause

• Chronic volume overload: tricuspid or pulmonic regurgitation, left-to-right shunt (atrial septal defect [ASD])

• Decompensated pressure overload: pulmonic stenosis, pulmonary veno-occlusive disease, pulmonary artery hypertension: primary, secondary (pulmonary embolism [PE], chronic obstructive pulmonary disease [COPD])

RIGHT ATRIUM

• Right ventricular (RV) failure of any cause

• Tricuspid valve disease

• Myxoma

• Ebstein’s anomaly

MULTICHAMBER ENLARGEMENT

• Hypertrophic cardiomyopathy

• Acromegaly

• Severe obesity

PERICARDIAL DISEASE

• Pericardial effusion with or without tamponade

• Effusive constrictive disease

• Pericardial cyst, loculated effusion

PSEUDOCARDIOMEGALY

• Epicardial fat

• Chest wall deformity (pectus excavatum, straight back syndrome)

• Low lung volumes

• Anteroposterior (AP) chest radiograph

• Mediastinal tumor, cyst

Cardiac Murmurs

CONTINUOUS

• Patent ductus arteriosus

• Pulmonary arteriovenous (AV) fistula

Cardiac Tamponade

• Chronic obstructive pulmonary disease (COPD)

• Constrictive pericardial disease

• Restrictive cardiomyopathy

• Right ventricular infarction

• Pulmonary embolism

Cardioembolism

• Acute MI

• Atrial fibrillation

• Left ventricular aneurysm

• Valvular heart disease (e.g., rheumatic mitral valve disease, mitral valve prolapse)

• Dilated cardiomyopathy

• Atrial septal defect

• Patent foramen ovale

• Cardioversion for atrial fibrillation

• Infective endocarditis

• Atrial septal aneurysm

• Sick sinus syndrome and cardiac arrhythmias

• Nonbacterial thrombotic endocarditis

• Prosthetic heart valves

• Atrial myxoma and other intracardiac tumors

• Cyanotic heart disease

• Balloon angioplasty

• Coronary artery bypass grafting

• Aneurysms of sinus of Valsalva

• Other: VVI pacing, ventricular support devices, heart transplantation, intracardiac defects with paradoxical embolism

Cardiogenic Shock

• Myocardial infarction

• Arrhythmias

• Pericardial effusion/tamponade

• Chest trauma

• Valvular heart disease

• Myocarditis

• Cardiomyopathy

• Congestive heart failure (CHF), end stage

Cardiomyopathy, Congestive

• Frank pulmonary disease

• Valvular dysfunction

• Pericardial abnormalities

• Coronary atherosclerosis

• Psychogenic dyspnea

Cardiomyopathy, Dilated

• Frank pulmonary disease

• Valvular dysfunction

• Pericardial abnormalities

• Coronary atherosclerosis

• Psychogenic dyspnea

Cardiomyopathy, Hypertrophic

• Coronary atherosclerosis

• Valvular dysfunction

• Pericardial abnormalities

• Chronic pulmonary disease

• Psychogenic dyspnea

Cardiomyopathy, Restrictive

• Coronary atherosclerosis

• Valvular dysfunction

• Pericardial abnormalities

• Chronic lung disease

• Psychogenic dyspnea

Carpal Tunnel

• Cervical radiculopathy

• Chronic tendinitis

• Vascular occlusion

• Reflex sympathetic dystrophy

• Osteoarthritis

• Other arthritides

• Other entrapment neuropathies

Cataracts

• Corneal lesions

• Retinal lesions, detached retina, tumors

• Vitreous disease, chronic inflammation

Cat-Scratch Disease

• Lymphogranuloma venereum

• Fungal diseases

• Benign and malignant tumors

• Tularemia

Cavernous Sinus Thrombosis

• Orbital cellulitis

• Internal carotid artery aneurysm

• Cerebrovascular accident (CVA)

• Migraine headache

• Allergic blepharitis

• Thyroid exophthalmos

Cavitary Lesion on Chest Radiograph ¹⁷

NECROTIZING INFECTIONS

• Bacteria: anaerobes, Staphylococcus aureus, enteric gram-negative bacteria, Pseudomonas aeruginosa, Legionella species, Haemophilus influenzae, Streptococcus pyogenes, Streptococcus pneumoniae, Rhodococcus, Actinomyces

• Mycobacteria: Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium avium-intracellulare (MAI)

• Bacteria-like: Nocardia species

• Fungi: Coccidioides immitis, Histoplasma capsulatum, Blastomyces hominis, Aspergillus species, Mucor species

• Parasitic: Entamoeba histolytica, Echinococcus, Paragonimus westermani

CAVITARY INFARCTION

• Bland infarction (with or without superimposed infection)

• Lung contusion

SEPTIC EMBOLISM

• S. aureus, anaerobes, others

VASCULITIS

• Wegener’s granulomatosis, periarteritis

NEOPLASMS

• Bronchogenic carcinoma, metastatic carcinoma, lymphoma

MISCELLANEOUS LESIONS

• Cysts, blebs, bullae, or pneumatocele with or without fluid collections

• Sequestration

• Empyema with air-fluid level

• Bronchiectasis

Celiac Disease

• Inflammatory bowel disease (IBD)

• Laxative abuse

• Intestinal parasitic infestations

• Other: irritable bowel syndrome, tropical sprue, chronic pancreatitis, Zollinger-Ellison syndrome, cystic fibrosis (children), lymphoma, eosinophilic gastroenteritis, short bowel syndrome, Whipple’s disease

Cellulitis

• Erythrasma

• Septic arthritis

• DVT

• Peripheral vascular insufficiency

• Paget’s disease of the breast

• Thrombophlebitis

• Acute gout

• Psoriasis

• Candida intertrigo

Cerebral Infarction Secondary to Inherited Disorders

• Homocystinuria

• Marfan syndrome

• Ehlers-Danlos syndrome

• Rendu-Osler-Weber syndrome

• Pseudoxanthoma elasticum

• Fabry’s disease

Cerebrovascular Disease, Ischemic ⁴⁰

CARDIAC DISORDERS

• Rheumatic heart disease

• Mural thrombus

• Arrhythmias

• Mitral valve prolapse

• Prosthetic heart valve

• Endocarditis

• Myxoma

• Paradoxical embolus

HEMATOLOGIC DISORDERS

• Thrombotic thrombocytopenic purpura

• Sickle cell disease

• Hypercoagulable states

• Polycythemia

• Thrombocytosis

• Leukocytosis

• Lupus anticoagulant

Cervical Cancer

• Cervical polyp

• Prolapsed uterine fibroid

• Preinvasive cervical lesions

• Neoplasia metastatic from a separate primary

Cervical Disk Disease

• Rotator cuff tendinitis

• Carpal tunnel syndrome

• Thoracic outlet syndrome

• Brachial neuritis

Cervical Dysplasia

• Metaplasia

• Hyperkeratosis

• Condyloma

• Microinvasive carcinoma

• Glandular epithelial abnormalities

• Adenocarcinoma in situ

• Metastatic tumor involvement of the cervix

Cervical Polyp

• Endometrial polyp

• Prolapsed myoma

• Retained products of conception

• Squamous papilloma

• Sarcoma

• Cervical malignant neoplasm

Cervicitis

• Carcinoma of the cervix

• Cervical erosion

• Cervical metaplasia

Chagas’ Disease

• Acute disease: early African trypanosomiasis, New World cutaneous and mucocutaneous leishmaniasis

• Chronic disease: idiopathic cardiomyopathy, idiopathic achalasia, congenital or acquired megacolon

Chancroid

• Syphilis

• Herpes simplex

• Lymphogranuloma venereum

• Granuloma inguinale

• Traumatic ulceration

• Behçet’s disease

• Crohn’s disease

Charcot’s Joint

• Osteomyelitis, cellulitis, abscess

• Infectious arthritis

• Osteoarthritis

• Rheumatoid and other inflammatory arthritides

Chest Pain, Children ⁴

GASTROINTESTINAL (LESS COMMON)

• Esophagitis (gastroesophageal reflux)

• Esophageal foreign body

• Esophageal spasm

• Cholecystitis

• Subdiaphragmatic abscess

• Perihepatitis (Fitz-Hugh–Curtis syndrome)

• Peptic ulcer disease

IDIOPATHIC (COMMON)

• Anxiety, hyperventilation

• Panic disorder

OTHER (LESS COMMON)

• Spinal cord or nerve root compression

• Breast-related pathologic condition

• Castleman’s disease (lymph node neoplasm)

Chest Pain, Nonpleuritic ⁹

• Cardiac: myocardial ischemia/infarction, myocarditis

• Esophageal: spasm, esophagitis, ulceration, neoplasm, achalasia, diverticula, foreign body

• Referred pain from subdiaphragmatic GI structures

• Gastric and duodenal: hiatal hernia, neoplasm, peptic ulcer disease (PUD)

• Gallbladder and biliary: cholecystitis, cholelithiasis, impacted stone, neoplasm

• Pancreatic: pancreatitis, neoplasm

• Dissecting aortic aneurysm

• Pain originating from skin, breasts, and musculoskeletal structures: herpes zoster, mastitis, cervical spondylosis

• Mediastinal tumors: lymphoma, thymoma

• Pulmonary: neoplasm, pneumonia, pulmonary embolism/infarction

• Psychoneurosis

• Chest pain associated with mitral valve prolapse

Chest Pain, Pleuritic

• Cardiac: pericarditis, postpericardiotomy/Dressler’s syndrome

• Pulmonary: pneumothorax, hemothorax, embolism/infarction, pneumonia, empyema, neoplasm, bronchiectasis, pneumomediastinum, TB, carcinomatous effusion

• GI: liver abscess, pancreatitis, esophageal rupture, Whipple’s disease with associated pericarditis or pleuritis

• Subdiaphragmatic abscess

• Pain originating from skin and musculoskeletal tissues: costochondritis, chest wall trauma, fractured rib, interstitial fibrositis, myositis, strain of pectoralis muscle, herpes zoster, soft tissue and bone tumors

• Collagen-vascular diseases with pleuritis

• Psychoneurosis

• Familial Mediterranean fever

Chickenpox (Varicella)

• Other viral infection

• Dermatitis herpetiformis

• Smallpox

Cholangitis

• Biliary colic

• Acute cholecystitis

• Liver abscess

• Peptic ulcer disease (PUD)

• Pancreatitis

• Intestinal obstruction

• Right kidney stone

• Hepatitis

• Pyelonephritis

Cholecystitis

• Hepatic: hepatitis, abscess, hepatic congestion, neoplasm, trauma

• Biliary: neoplasm, stricture

• Gastric: peptic ulcer disease (PUD), neoplasm, alcoholic gastritis, hiatal hernia

• Pancreatic: pancreatitis, neoplasm, stone in the pancreatic duct or ampulla

• Renal: calculi, infection, inflammation, neoplasm, ruptured kidney

• Pulmonary: pneumonia, pulmonary infarction, right-sided pleurisy

• Intestinal: retrocecal appendicitis, intestinal obstruction, high fecal impaction

• Cardiac: myocardial ischemia (particularly involving the inferior wall), pericarditis

• Cutaneous: herpes zoster

• Trauma

• Fitz-Hugh–Curtis syndrome (perihepatitis)

• Subphrenic abscess

• Dissecting aneurysm

• Nerve root irritation caused by osteoarthritis of the spine

Cholelithiasis

• Peptic ulcer disease (PUD)

• Gastroesophageal reflux disease (GERD)

• Inflammatory bowel disease (IBD)

• Pancreatitis

• Neoplasms

• Nonulcer dyspepsia

• Irritable bowel syndrome

Cholestasis ¹⁴

• Extrahepatic

• Choledocholithiasis

• Bile duct stricture

• Cholangiocarcinoma

• Pancreatic carcinoma

• Chronic pancreatitis

• Papillary stenosis

• Ampullary cancer

• Primary sclerosing cholangitis

• Choledochal cysts

• Parasites (e.g., Ascaris, Clonorchis sinensis)

• AIDS

• Cholangiography

• Biliary atresia

• Portal lymphadenopathy

• Mirizzi’s syndrome

• Intrahepatic

• Viral hepatitis

• Alcoholic hepatitis

• Drug induced

• Ductopenia syndromes

• Primary biliary cirrhosis

• Benign recurrent intrahepatic cholestasis

• Byler’s disease

• Primary sclerosing cholangitis

• Alagille’s syndrome

• Sarcoid

• Lymphoma

• Postoperative

• Total parenteral nutrition

• α₁-Antitrypsin deficiency

Chorea

• Medications (e.g., neuroleptics, tricyclics, antiparkinsonian drugs)

• Cerebral palsy

• Huntington’s disease

• Benign hereditary chorea

• Thyroid disorder (hyperthyroidism, hypothyroidism)

• Friedreich’s ataxia

• Ataxia-telangiectasia

• Hypoglycemia, hyperglycemia

• Electrolyte abnormalities (hyponatremia, hypocalcemia, hypomagnesemia, hypernatremia)

• Vitamin B₁₂ deficiency

• Systemic lupus erythematosus (SLE)

• Wilson’s disease

• Alcohol

• Cocaine

• Carbon monoxide poisoning

• Mercury poisoning

Choreoathetosis ²⁹

SYSTEMIC DISEASES

• Systemic lupus erythematosus (SLE)

• Polycythemia

• Thyrotoxicosis

• Rheumatic fever

• Cirrhosis of the liver (acquired hepatocerebral degeneration)

• Diabetes mellitus (DM)

• Wilson’s disease

PRIMARY DEGENERATIVE BRAIN DISEASES

• Huntington’s chorea

• Olivopontocerebellar atrophies

• Neuroacanthocytosis

FOCAL BRAIN DISEASES

• Hemichorea

• Stroke

• Tumor

• Arteriovenous malformation

DRUG-INDUCED CHOREOATHETOSIS

• Parkinson’s disease drugs: levodopa

• Epilepsy drugs: phenytoin, carbamazepine, phenobarbital, gabapentin, valproate

• Psychostimulant drugs: cocaine, amphetamine, methamphetamine, dextroamphetamine, methylphenidate, pemoline, psychotropic drugs, lithium, tricyclic antidepressant drugs

• Oral contraceptive drugs: cimetidine

Chronic Fatigue Syndrome

• Psychosocial depression, dysthymia, anxiety-related disorders, and other psychiatric diseases

• Infectious diseases (subacute bacterial endocarditis [SBE], Lyme disease, fungal diseases, mononucleosis, HIV infection, chronic hepatitis B or C, TB, chronic parasitic infections)

• Autoimmune diseases: systemic lupus erythematosus (SLE), myasthenia gravis, multiple sclerosis, thyroiditis, rheumatoid arthritis (RA)

• Endocrine abnormalities: hypothyroidism, hypopituitarism, adrenal insufficiency, Cushing’s syndrome, diabetes mellitus (DM), hyperparathyroidism, pregnancy, reactive hypoglycemia

• Occult malignant disease

• Substance abuse

• Systemic disorders: chronic renal failure, chronic obstructive pulmonary disease (COPD), cardiovascular disease, anemia, electrolyte abnormalities, liver disease

• Other: inadequate rest, sleep apnea, narcolepsy, fibromyalgia, sarcoidosis, medications, toxic agent exposure, Wegener’s granulomatosis

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

• Guillain-Barré syndrome (GBS), the difference being that GBS evolves during a maximum of 4 weeks and CIDP usually progresses during at least 8 weeks.

• Diabetic neuropathy: the distinction can often be made with electrodiagnostic studies, which typically show axonal physiology in diabetic neuropathy.

• Mononeuritis multiplex

• Monoclonal gammopathy of undetermined significance, plasma cell dyscrasia, osteosclerotic myeloma, and HIV infection are not so much part of the differential diagnosis but may coexist and so should always be sought.

Chronic Obstructive Pulmonary Disease (COPD)

• Congestive heart failure (CHF)

• Asthma

• Respiratory infections

• Sleep apnea, obstructive

• Hypothyroidism

Churg-Strauss Syndrome

• Polyarteritis nodosa

• Wegener’s granulomatosis

• Sarcoidosis

• Loeffler’s syndrome

• Henoch-Schönlein purpura

• Allergic bronchopulmonary aspergillosis

• Rheumatoid arthritis (RA)

• Leukocytoclastic vasculitis

Chylothorax

• Post lymph node dissection of neck or chest

• Subclavian venous catheterization

• Thoracic aneurysm repair

• Trauma to chest and neck

• Mediastinal tumor resection

• Esophagectomy, pneumonectomy

• Lymphangitis, mediastinitis

• Neoplasms (lymphoma; carcinoma of esophagus, lung; mediastinal malignant neoplasms)

• Sympathectomy

• Venous thrombosis

• Congenital

Cicatricial Pemphigoid

• Bullous pemphigoid

• Erythema multiforme

• Dermatitis herpetiformis

• Linear IgA dermatosis

• Pemphigus

• Stevens-Johnson’s syndrome

• Herpes simplex, herpes zoster

Cirrhosis, Primary Biliary

• Drug-induced cholestasis

• Other etiologies of chronic liver disease and cirrhosis: alcoholic cirrhosis, viral hepatitis (chronic), primary sclerosing cholangitis, autoimmune chronic active hepatitis, chemical/toxin-induced cirrhosis, other hereditary or familial disorders (e.g., cystic fibrosis, α₁-antitrypsin deficiency)

Claudication

• Spinal stenosis (neurogenic claudication)

• Muscle cramps

• Degenerative osteoarthritic joint disease, particularly of the lumbar spine and hips

• Compartment syndrome

Cloudy Urine

• Concentrated urine

• Use of multivitamin supplements

• Diet high in purine-rich foods

• Pyuria

• Phosphaturia

• Urinary tract infection

• Lipiduria

• Chyluria

• Hyperoxaluria

Clubbing

• Pulmonary neoplasm (lung, pleura)

• Other neoplasm (GI, liver, Hodgkin’s disease, thymus, osteogenic sarcoma)

• Pulmonary infectious process (empyema, abscess, bronchiectasis, TB, chronic pneumonitis)

• Extrapulmonary infectious process (subacute bacterial endocarditis, intestinal TB, bacterial or amebic dysentery, arterial graft sepsis)

• Pneumoconiosis

• Cystic fibrosis

• Sarcoidosis

• Cyanotic congenital heart disease

• Endocrine (Graves’ disease, hyperparathyroidism)

• Inflammatory bowel disease (IBD)

• Celiac disease

• Chronic liver disease, cirrhosis (particularly biliary and juvenile)

• Pulmonary arteriovenous (AV) malformations

• Idiopathic

• Thyroid acropachy

• Hereditary (pachydermoperiostitis)

• Chronic trauma (jackhammer operators, machine workers)

Cobalamin Deficiency ²¹

NUTRITIONAL COBALAMIN DEFICIENCY (I.E., INSUFFICIENT COBALAMIN INTAKE)

• Vegetarians, poverty-imposed near-vegetarians, breast-fed infants of mothers with pernicious anemia

ABNORMAL INTRAGASTRIC EVENTS (I.E., INADEQUATE PROTEOLYSIS OF FOOD COBALAMIN)

• Atrophic gastritis, partial gastrectomy with hypochlorhydria, proton pump inhibitors, H₂ blockers

LOSS OR ATROPHY OF GASTRIC OXYNTIC MUCOSA (I.E., DEFICIENT INTRINSIC FACTOR [IF] MOLECULES)

• Total or partial gastrectomy, pernicious anemia, caustic destruction (lye)

ABNORMAL EVENTS IN SMALL BOWEL LUMEN

• Inadequate pancreatic protease (e.g., R-cobalamin not degraded, cobalamin not transferred to IF)

• Insufficient pancreatic protease (i.e., pancreatic insufficiency)

• Inactivation of pancreatic protease (i.e., Zollinger-Ellison syndrome)

• Usurping of luminal cobalamin (i.e., inadequate cobalamin binding to IF)

• By bacteria; during stasis syndromes (e.g., blind loops, pouches of diverticulosis, strictures, fistulas, anastomosis); impaired bowel motility (e.g., scleroderma); hypogammaglobulinemia

• By Diphyllobothrium latum (fish tapeworm)

DISORDERS OF ILEAL MUCOSA/IF-COBALAMIN RECEPTORS (I.E., IF-COBALAMIN NOT BOUND TO IF-COBALAMIN RECEPTORS)

• Diminished or absent IF-cobalamin receptors (e.g., ileal bypass, resection, fistula)

• Abnormal mucosal architecture/function (e.g., tropical or nontropical sprue, Crohn’s disease, tuberculous ileitis, infiltration by lymphomas, amyloidosis)

• IF/post IF–cobalamin receptor defects (e.g., Imerslund-Graesbeck syndrome, transcobalamin II [TC II] deficiency)

• Drug effects (e.g., Slow-K, metformin, cholestyramine, colchicine, neomycin)

DISORDERS OF PLASMA COBALAMIN TRANSPORT (I.E., TC II–COBALAMIN NOT DELIVERED TO TC II RECEPTORS)

• Congenital TC II deficiency, defective binding of TC II–cobalamin to TC II receptors (rare)

METABOLIC DISORDERS (I.E., COBALAMIN NOT USED BY CELLS)

• Inborn enzyme errors (rare)

• Acquired disorders (e.g., cobalamin functionally inactivated by irreversible oxidation, N₂O inhalation)

Cocaine Overdose

• Methamphetamine (“speed”) abuse

• Methylenedioxyamphetamine (“ecstasy”) abuse

• Cathinone (“khat”) abuse

• Lysergic acid diethylamide (LSD) abuse

• Hyperthyroidism, panic disorder, pheochromocytoma

Coccidioidomycosis

• Acute pulmonary coccidioidomycoses: community-acquired pneumonias caused by Mycoplasma and Chlamydia; granulomatous diseases, such as Mycobacterium tuberculosis and sarcoidosis; other fungal diseases, such as Blastomyces dermatitidis and Histoplasma capsulatum

• Coccidioidomas: true neoplasms

Colic, Acute Abdominal ³⁹

• Acute gastroenteritis

• Food poisoning

• Nonspecific causes, anxiety disorder

• Constipation

• Gastric outlet obstruction

• Chronic peptic ulceration

• Gastric cancer

Color Changes, Cutaneous ³⁵

BROWN

• Generalized: pituitary, adrenal, liver disease; adrenocorticotropic hormone (ACTH)–producing tumor (e.g., oat cell lung carcinoma)

• Localized: nevi, neurofibromatosis

WHITE

• Generalized: albinism

• Localized: vitiligo, Raynaud’s syndrome

RED (ERYTHEMA)

• Generalized: fever, polycythemia, urticaria, viral exanthems

• Localized: inflammation, infection, Raynaud’s syndrome

YELLOW

• Generalized: liver disease, chronic renal disease, anemia

• Generalized (except sclera): hypothyroidism, increased intake of vegetables containing carotene

• Localized: resolving hematoma, infection, peripheral vascular insufficiency

BLUE

• Lips, mouth, nail beds: cardiovascular and pulmonary diseases, Raynaud’s syndrome

Colorado Tick Fever

• Rocky Mountain spotted fever

• Influenza

• Leptospirosis

• Infectious mononucleosis

• Cytomegalovirus (CMV) infection

• Idiopathic thrombocytopenic purpura (ITP)

• Thrombotic thrombocytopenic purpura (TTP)

• Kawasaki’s disease

• Toxic shock syndrome

• Vasculitis

Colorectal Cancer

• Diverticular disease

• Strictures

• Inflammatory bowel disease (IBD)

• Infectious or inflammatory lesions

• Adhesions

• Arteriovenous malformations

• Metastatic carcinoma (prostate, sarcoma)

• Extrinsic masses (cysts, abscesses)

Coma

• Vascular: hemorrhage, thrombosis, embolism

• CNS infections: meningitis, encephalitis, cerebral abscess

• Cerebral neoplasms with herniation

• Head injury: subdural hematoma, cerebral concussion, cerebral contusion

• Drugs: narcotics, sedatives, hypnotics

• Ingestion or inhalation of toxins: carbon monoxide (CO), alcohol, lead

• Metabolic disturbances

• Hypoxia

• Acid-base disorders

• Hypoglycemia, hyperglycemia

• Hepatic failure

• Electrolyte disorders

• Uremia

• Hypothyroidism

• Hypothermia, hyperthermia

• Hypotension, malignant hypertension

• Postictal

Coma, Normal Computed Tomography ¹

MENINGEAL DISORDERS

• Subarachnoid hemorrhage (uncommon)

• Bacterial meningitis

• Encephalitis

• Subdural empyema

SEIZURES

• Prolonged postictal state

• Spike-wave stupor

HYPOTHERMIA OR HYPERTHERMIA

• Brainstem ischemia

• Basilar artery stroke

• Brainstem or cerebellar hemorrhage

• Conversion or malingering

Coma, Pediatric Population ³²

ANOXIA

• Birth asphyxia

• Carbon monoxide (CO) poisoning

• Croup/epiglottitis

• Meconium aspiration

INFECTION

• Hemolysis

• Blood loss

• Hydrops fetalis

• Meningoencephalitis

• Sepsis

• Postimmunization encephalitis

HYPERTENSIVE ENCEPHALOPATHY

• Coarctation of aorta

• Nephritis

• Vasculitis

• Pheochromocytoma

ISCHEMIA

• Hypoplastic left side of heart

• Shunting lesions

• Aortic stenosis

• Cardiovascular collapse (any cause)

PURPURIC CAUSES

• Disseminated intravascular coagulation

• Hemolytic-uremic syndrome

• Leukemia

• Thrombotic purpura

HYPERCAPNIA

• Cystic fibrosis

• Bronchopulmonary dysplasia

• Congenital lung anomalies

NEOPLASM

• Medulloblastoma

• Glioma of brainstem

• Posterior fossa tumors

DRUGS/TOXINS

ELECTROLYTE ABNORMALITIES

• Hypernatremia (diarrhea, dehydration, salt poisoning)

• Hyponatremia (syndrome of inappropriate antidiuretic hormone [SIADH], androgenital syndrome, gastroenteritis)

• Hyperkalemia (renal failure, salicylism, androgenitalism)

• Hypokalemia (diarrhea, hyperaldosteronism, salicylism, diabetic ketoacidosis [DKA])

• Hypocalcemia (vitamin D deficiency, hyperparathyroidism)

• Severe acidosis (sepsis, cold injury, salicylism, DKA)

HYPOGLYCEMIA

• Birth injury or stress

POSTSEIZURE

• Renal causes: nephritis, hypoplastic kidneys

• Hepatic causes: acute hepatitis, fulminant hepatic failure, inborn metabolic errors, bile duct atresia

Condyloma Acuminatum

• Abnormal anatomic variants or skin tags around labia minora and introitus, pearly penile papules

• Dysplastic warts

• Seborrheic keratosis

• Erythroplasia of Queyrat

• Lichen planus

• Verrucous carcinoma

• Bowenoid papulosis

• Syphilis

Congenital Adrenal Hyperplasia

• Precocious puberty

• Polycystic ovary syndrome

• Androgen resistance syndromes

• Pseudohermaphroditism

• Mixed gonadal dysgenesis

• Testicular carcinoma

• Leydig cell tumors

• Adrenocortical carcinoma

• Addison’s disease

• Pituitary adenoma

Congestive Heart Failure

• Cirrhosis

• Nephrotic syndrome

• Venous occlusive disease

• Chronic obstructive pulmonary disease (COPD), asthma

• Pulmonary embolism

• Acute respiratory distress syndrome (ARDS)

• Heroin overdose

• Pneumonia

• Hypothyroidism

Conjunctival Neoplasm

MALIGNANT

• Squamous cell carcinoma

• Melanoma

• Sebaceous carcinoma

• Kaposi’s sarcoma

• Metastatic neoplasms

BENIGN

Conjunctivitis

• Canalicular obstruction

• Acute glaucoma

Constipation

• Intestinal obstruction

• Fecal impaction

• Diverticular disease

• GI neoplasm

• Strangulated femoral hernia

• Gallstone ileus

• Tuberculous stricture

• Inflammatory bowel disease (IBD)

• Hematoma of bowel wall, secondary to trauma or anticoagulants

• Poor dietary habits: insufficient bulk in diet, inadequate fluid intake

• Change from daily routine: travel, hospital admission, physical inactivity

• Acute abdominal conditions: renal colic, salpingitis, biliary colic, appendicitis, ischemia

• Hypercalcemia or hypokalemia, uremia

• Irritable bowel syndrome, pregnancy, anorexia nervosa, depression

• Painful anal conditions: hemorrhoids, fissure, stricture

• Decreased intestinal peristalsis: old age, spinal cord injuries, myxedema, diabetes, multiple sclerosis, parkinsonism and other neurologic diseases

• Drugs: codeine, morphine, antacids with aluminum, verapamil, anticonvulsants, anticholinergics, disopyramide, cholestyramine, alosetron, iron supplements

• Hirschsprung’s disease, meconium ileus, congenital atresia in infants

Constipation, Adult Patient ³⁹

NO GROSS STRUCTURAL ABNORMALITY

• Inadequate fiber intake

• Irritable bowel syndrome (associated with abdominal pain) or functional constipation

• Idiopathic slow-transit constipation

• “Obstructed defecation”: pelvic floor dysfunction (or dyssynergia)

NEUROLOGIC CAUSES

• Diabetic autonomic neuropathy

• Damage to the sacral parasympathetic outflow

• Spinal cord damage or disease (e.g., multiple sclerosis)

• Parkinson’s disease

• Blunting of consciousness, mental retardation, psychosis

• Pain induced by straining (e.g., sciatic nerve compression)

ENDOCRINE OR METABOLIC CAUSES

PSYCHOLOGICAL DISORDERS

• Depression

• Anorexia nervosa

• Denied bowel habit

DRUG SIDE EFFECTS

Contact Dermatitis (Contact Eczema)

• Impetigo

• Lichen simplex chronicus

• Atopic dermatitis

• Nummular eczema

• Seborrheic dermatitis

Conversion Disorder

• Malingering: dysfunction is consciously created for the purpose of secondary gain or avoidance of noxious duties.

• Factitious disorder (e.g., Munchausen’s syndrome): dysfunction is consciously created for the purpose of assuming the patient role.

• Somatization: a related disorder in which psychological difficulties are manifested with a wide range of somatic complaints that affect several organ systems.

Corneal Abrasion

• Herpes ulcers and other corneal ulcers

• Foreign body in the cornea (be certain it is not a keratitis)

• Acute angle glaucoma

Corneal Sensation, Decreased

• Herpes (simplex, zoster)

• Contact lens wear

• Topical agents (NSAIDs, anesthetics, b-blockers)

• Diabetes

• Eye trauma

• Post surgery

Corneal Ulceration

• Pseudomonas and pneumococcus infection—virulent

• Moraxella, Staphylococcus, alpha-streptococcus infection—less virulent

• Herpes simplex infection or disease caused by other viruses

Cor Pulmonale

• Pulmonary thromboembolic disease

• Chronic obstructive pulmonary disease (COPD)

• Interstitial lung disease

• Neuromuscular diseases causing hypoventilation (e.g., antilymphocyte serum [ALS])

• Collagen-vascular disease (e.g., systemic lupus erythematosus [SLE]; calcinosis cutis, Raynaud’s phenomenon, esophageal dysfunction, sclerodactyly, telangiectasia [CREST]; systemic sclerosis)

• Pulmonary venous disease

• Primary pulmonary hypertension

Costochondritis

• Tietze’s syndrome

• Cardiovascular disease

• GI disease

• Pulmonary disease

• Osteoarthritis

• Cervical disk syndrome

Cough

• Infectious process (viral, bacterial)

• Postinfectious

• “Smoker’s cough”

• Rhinitis (allergic, vasomotor, postinfectious)

• Asthma

• Exposure to irritants (noxious fumes, smoke, cold air)

• Drug induced (especially angiotensin-converting enzyme [ACE] inhibitors, b-blockers)

• Gastroesophageal reflux disease (GERD)

• Interstitial lung disease

• Lung neoplasms

• Lymphomas, mediastinal neoplasms

• Bronchiectasis

• Cardiac (congestive heart failure, pulmonary edema, mitral stenosis, pericardial inflammation)

• Recurrent aspiration

• Inflammation of larynx, pleura, diaphragm, mediastinum

• Cystic fibrosis

• Anxiety

• Other: pulmonary embolism, foreign body inhalation, aortic aneurysm, Zenker’s diverticulum, osteophytes, substernal thyroid, thyroiditis, polymyalgia rheumatica (PMR)

Craniopharyngioma

• Pituitary adenoma

• Empty sella syndrome

• Pituitary failure of any cause

• Primary brain tumors (e.g., meningiomas, astrocytomas)

• Metastatic brain tumors

• Other brain tumors

• Cerebral aneurysm

Creutzfeldt-Jakob Disease

• Alzheimer’s disease

• Frontotemporal dementia

• Lewy body disease

• Vascular dementia

• Others (hydrocephalus, infectious, vitamin deficiency, endocrine)

Crohn’s Disease

• Ulcerative colitis

• Infectious diseases (TB, Yersinia, Salmonella, Shigella, Campylobacter)

• Parasitic infections (amebic infection)

• Pseudomembranous colitis

• Ischemic colitis in elderly patients

• Lymphoma

• Colon carcinoma

• Diverticulitis

• Irradiation enteritis

• Collagenous colitis

• Fungal infections (Histoplasma, Actinomyces)

• Gay bowel syndrome (in homosexual patient)

• Carcinoid tumors

• Celiac sprue

• Mesenteric adenitis

Cryoglobulinemia

• Serum sickness

• Antiphospholipid antibody syndrome

• Sarcoidosis

• Waldenström’s hyperglobulinemia

• Septic vasculitis

• Polyarteritis nodosa

Cryptococcosis

• Acute or subacute meningitis (caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, Listeria monocytogenes, Mycobacterium tuberculosis, Histoplasma capsulatum, viruses)

• Intracranial mass lesion (neoplasms, toxoplasmosis, TB)

• Pulmonary involvement confused with Pneumocystis jiroveci pneumonia when diffuse or confused with TB or bacterial pneumonia when focal or involving the pleura

• Skin lesions confused with bacterial cellulitis or molluscum contagiosum

Cryptorchidism

Cryptosporidiosis

• Campylobacter

• Clostridium difficile

• Entamoeba histolytica

• Mycobacterium avium

Cubital Tunnel Syndrome

• Medial epicondylitis

• Medial elbow instability

• Carpal tunnel syndrome

• Cervical disk syndrome with radicular arm symptoms

• Ulnar nerve compression at wrist (Guyon’s canal)

Cushing’s Syndrome

• Alcoholic pseudo-Cushing’s syndrome (endogenous cortisol overproduction)

• Obesity associated with diabetes mellitus (DM)

• Adrenogenital syndrome

Cutaneous Infections, Athletes

• Tinea pedis

• Tinea cruris

• Molluscum contagiosum

Cutaneous Larva Migrans

• Superficial thrombophlebitis

• Mondor’s disease

• Lichen striatus

• Phytophotodermatitis

• Cercarial dermatitis

• Bacterial folliculitis

• Tinea pedis/corporis

• Impetigo

• Erythema chronicum migrans of Lyme disease

• Ground itch

• Toxocariasis

Cutis Laxa

• Anetoderma (localized area of lax skin often with herniation of underlying tissues)

• Morphea

• Atrophoderma (disorders characterized by a depression in the skin surface)

• Pseudoxanthoma elasticum

• Ehlers-Danlos syndrome

• Marfan syndrome

Cyanosis

• Congenital heart disease with right-to-left shunt

• Pulmonary embolism

• Hypoxia

• Pulmonary edema

• Pulmonary disease (oxygen diffusion and alveolar ventilation abnormalities)

• Hemoglobinopathies

• Decreased cardiac output

• Vasospasm

• Arterial obstruction

• Pulmonary atrioventricular (AV) fistulas

• Elevated hemidiaphragm

• Neoplasm (bronchogenic carcinoma, mediastinal neoplasm, intrahepatic lesion)

• Substernal thyroid

• Infectious process (pneumonia, empyema, TB, subphrenic abscess, hepatic abscess)

• Atelectasis

• Idiopathic

• Eventration

• Phrenic nerve dysfunction (myelitis, myotonia, herpes zoster)

• Trauma to phrenic nerve or diaphragm (e.g., surgery)

• Aortic aneurysm

• Intra-abdominal mass

• Pulmonary infarction

• Pleurisy

• Radiation therapy

• Rib fracture

• Superior vena cava syndrome

Cylindroma

• Basal cell carcinoma

• Pilar cyst

• Pilomatricoma

• Follicular neoplasm

• Eccrine spiradenoma

Cysticercosis

• Idiopathic epilepsy

• Migraine

• Vasculitides

• Primary neoplasia of CNS

• Toxoplasmosis

• Brain abscess

• Granulomatous disease such as sarcoidosis

Cystic Fibrosis

• Immunodeficiency states

• Celiac disease

• Asthma

• Recurrent pneumonia

• Chronic aspiration

Cytomegalovirus Infection

• Congenital: acute viral, bacterial, parasitic infections including other congenitally transmitted agents (toxoplasmosis, rubella, syphilis, pertussis, croup, bronchitis)

• Acquired: Epstein-Barr virus (EBV) mononucleosis; viral hepatitis: A, B, C; cryptosporidiosis; toxoplasmosis; Mycobacterium avium infections; human herpesvirus 6; drug reaction; acute HIV infection

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