Acanthosis nigricans

Published on 02/04/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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167 Acanthosis nigricans

Instruction

Perform a general examination.

Salient features

History

• Age (>40 years of age more likely to be associated with malignancy; in younger individuals more likely to be associated with endocrinopathies)

• Carcinoma stomach or other neoplasms (in 80% the cancer is abdominal and in 60% the cancer is in the stomach): symptoms of weight loss, asthenia and decreased appetite

• Diabetes mellitus (insulin-resistant diabetes)

• Endocrinopathies: acromegaly, Cushing’s disease, polycystic ovaries, hypothyroidism, hyperthyroidism.

Examination

• Black, velvety overgrowth seen in the axillae (Fig. 167.1), neck, umbilicus, nipples, groins or facial skin

• Acrochordons or skin tags may accompany acanthosis nigricans and occur in similar areas.

image

Fig. 167.1 Acanthosis nigricans in the axilla.

Proceed as follows:

• Look for the following signs:

• Tripe palms (roughness of the palmar and plantar skin; Fig. 167.2)
• Filiform growths around the face and mouth, and over the tongue (when mouth and tongue are involved it is highly suggestive of an underlying neoplasm) (Fig. 167.3).

• Tell the examiner that you would like to investigate for:

• underlying malignancy, in particular adenocarcinoma of the stomach
• for endocrine disorders (diabetes, Cushing syndrome, acromegaly).

• Comment if the patient is obese or non-obese (when pigmented verrucous areas develop in the body folds of non-obese individuals, about 80–90% have an underlying gastric cancer).

image

Fig. 167.2 Tripe palms.

(With permission from Moore, Devere 2008.)

image

Fig. 167.3 Malignant acanthosis nigricans in the mouth.

(With permission from Moore, Devere 2008.)

Diagnosis

This patient has a velvety black overgrowth in the axillae (lesion) and I would like to exclude an underlying adenocarcinoma, particularly of the stomach (aetiology).

Advanced-level questions

What are the types of acanthosis nigricans?

(1) Benign, (2) obesity-associated, (3) syndromic, (4) malignant, (5) acral, (6) unilateral, (7) medication-induced, and (8) mixed type.

What is the histology of acanthosis nigricans?

• Undulating epidermis with numerous sharp peaks and valleys

• Variable amount of hyperplasia, hyperkeratosis and slight pigmentation of the basal cell layer (but no melanocytic hyperplasia).

With which conditions is acanthosis nigricans associated?

• Benign conditions:

• Diabetes, associated with marked insulin resistance
• Cushing syndrome
• Acromegaly
• Stein–Leventhal syndrome
• Obesity: nearly 75% of these patients develop acanthosis nigricans.

• Malignant conditions (caused by abnormal production of epidermal growth factors):

• Adenocarcinomas (usually stomach, GI tract, and uterus; less commonly lung, ovary, breast and prostate)
• Lymphomas (rarely).

What is the relationship between the course of the skin lesion and the underlying malignancy?

Acanthosis nigricans may precede the neoplasm by >5 years. In about two-thirds of cases, the course parallels that of the tumour, including remission with cure.

Mention some cutaneous manifestations of visceral malignancy

• Dermatomyositis (in individuals >40 years, the prevalence of internal malignancy particularly lung and breast cancer is increased)

• Migratory thrombophlebitis

• Ichthyosis (when acquired suggests GI leiomyosarcoma, lymphoma, multiple myeloma)

• Paget’s disease of the nipple

• Tylosis or palmar hyperkeratosis (suggests oesophageal cancer)

• Lesar-Trelat sign, which is the sudden appearance of multiple seborrheic keratosis and suggests underlying cancer in the elderly

• Necrotic migratory erythema suggests tumours of the alpha cells of the pancreas, which secrete glucagon

• Bazex syndrome or acrokeratosis paraneoplastica suggests malignancy of the upper respiratory tract, particularly squamous cell carcinomas of the mouth, pharynx, larynx, oesophagus and bronchus

• Lymphamatoid papulosis is cutaneous lymphoid infiltration associated with T cell lymphomas or Hodgkin’s disease.

What is the therapy for acanthosis nigricans?

Some patients have benefited from medications such as metformin, oral isotretinoin, topical retinoic acid, topical salicylic acid and oral fish oil. Successes have been reported with the CO laser and the long-pulsed Alexandrite laser.

Note: Acanthosis is hyperplasia of the stratum spinosum of the epidermis.

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