Diseases of Subcutaneous Tissue

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Chapter 652 Diseases of Subcutaneous Tissue

Diseases involving the subcutis are usually characterized by necrosis and/or inflammation; they may occur either as a primary event or as a secondary response to various stimuli or disease processes. The principal diagnostic criteria relates to the appearance and distribution of the lesions, associated symptoms, results of laboratory studies, histopathology, and natural history and exogenous provocative factors of these conditions.

652.1 Panniculitis and Erythema Nodosum

Inflammation of fibrofatty subcutaneous tissue may primarily involve the fat lobule or, alternatively, the fibrous septum that compartmentalizes the fatty lobules. Lobular panniculitis that spares the subcutaneous vasculature includes post-steroid panniculitis, lupus erythematosus profundus, pancreatic panniculitis, α1-antitrypsin deficiency, subcutaneous fat necrosis of the newborn, sclerema neonatorum, cold panniculitis, subcutaneous sarcoidosis, and factitial panniculitis. Lobar panniculitis with vasculitis occurs in erythema induratum and, occasionally, as a feature of Crohn disease (Chapter 328.2). Inflammation predominantly within the septum, sparing the vasculature, may be seen in erythema nodosum (Table 652-1 and Fig. 652-2), necrobiosis lipoidica, progressive systemic sclerosis (Chapter 154), and subcutaneous granuloma annulare (Chapter 649). Septal panniculitis that includes inflammation of the vessels is found primarily in leukocytoclastic vasculitis and polyarteritis nodosa (Chapter 161).

Table 652-1 ETIOLOGY OF ERYTHEMA NODOSUM

VIRUSES

Epstein-Barr, hepatitis B, mumps

FUNGI

Coccidioidomycosis, histoplasmosis, blastomycosis, sporotrichosis

BACTERIA AND OTHER INFECTIOUS AGENTS

Group A streptococcus,* tuberculosis,* Yersinia, cat-scratch disease, leprosy, leptospirosis, tularemia, mycoplasma, Whipple disease, lymphogranuloma venereum, psittacosis, brucellosis

OTHER

Sarcoidosis, inflammatory bowel disease,* estrogen-containing oral contraceptives,* systemic lupus erythematosus, Behçet syndrome, severe acne, Hodgkin disease, lymphoma, sulfonamides, bromides, Sweet syndrome, pregnancy, idiopathic*

* Common.

image

Figure 652-2 Tender red nodules with indistinct borders in a teenage girl with erythema nodosum.

(From Weston AL, Lane AT, Morelli JG: Color textbook of pediatric dermatology, ed 3, St Louis, 2002, Mosby, p 212.)

Erythema Nodosum

Erythema nodosum is a nodular, erythematous hypersensitivity reaction that typically appears with multiple lesions on the exterior surfaces of the arms and legs in the pretibial area (more common) and less often in other cutaneous areas containing subcutaneous fat. The lesions vary in size from 1 to 6 cm, are symmetric, and are oval with the longer axis parallel to the extremity. They initially appear bright or dull red but progress to a brown or purple; they are tense and painful and usually do not ulcerate (see Fig. 652-2). Initial lesions may resolve in 1-2 wk, but new lesions may continue to appear for 2-6 wk. Repeat episodes may occur weeks to months later. Prior to or immediately at the onset of lesions, there may be systemic manifestations that include fever, malaise, arthralgias (50-90%) and rheumatoid factor negative arthritis.

The etiology is unknown in 30-50% of pediatric cases of erythema nodosum; other etiologies are noted in Table 652-1. Group A streptococcal infection and inflammatory disorders (inflammatory bowel disease) are common etiologies in children; sarcoidosis should be considered in young adults.

Treatment includes that of the underlying disease as well as symptomatic relief with nonsteroidal antiinflammatory agents. Salicylates, supersaturated solution of potassium iodide (oral), colchicine, intraintestinal injections of steroidsand, in severe, persistent, or recurrent lesions, oral steroids have been employed. The idiopathic form is a self-limited disorder.

Lupus Erythematosus Profundus (Lupus Erythematosus Panniculitis)