AGE OF ONSET More commonly in adulthood.

Most likely are caused by increased activation of growth factor receptor proteins.

Insidious onset, except malignant type, which is rapid. The first visible change is darkening of pigmentation.

SKIN LESIONS Darkening of pigmentation (Fig. 5-1). As skin thickens, it appears velvety; skin lines accentuated; surface becomes rugose, mamillated. Often has many skin tags in body folds and neck. Malignant type: Hyperkeratosis and hyperpigmentation more pronounced (Fig. 5-2A). Involvement of oral mucosa and vermilion border of lips (Fig. 5-2B). Hyperkeratosis of the palms/soles, with accentuation of papillary markings, "Tripe hands" (Fig. 5-2C).

DISTRIBUTION Most commonly, axillae (Fig. 5-1); neck (back, sides), groins (Fig. 5-2A), anogenital, antecubital fossae, knuckles, inframammary, and umbilicus. In malignant type, also periocular, perioral, mammillary, and palms (tripe palms) (Fig. 5-2C).

MUCOUS MEMBRANES Oral mucosa: Velvety texture with delicate furrows. Type 5: Mucous membranes and mucocutaneous junctions commonly involved; warty papillomatous perioral thickenings (Fig. 5-2B).

CHEMISTRY Rule out diabetes mellitus, metabolic syndrome.

DERMATOPATHOLOGY Papillomatosis, hyperkeratosis; epidermis thrown into irregular folds, showing various degrees of acanthosis.

IMAGING AND ENDOSCOPY Rule out associated malignancy.

CLINICAL FINDINGS Dark thickened flexural skin: confluent and reticulated papillomatosis (Gougerot-Carteaud syndrome), pityriasis versicolor, X-linked ichthyosis, retention hyperkeratosis, and nicotinic acid ingestion.

Can improve when known cause is removed. Otherwise chronic.

Symptomatic. Treat associated disorder. Topical keratolytics, topical steroids, topical vitamin D analogs.