Acanthosis Nigricans
The exact incidence of AN is unknown. In an unselected population of 1412 children, AN were present in 7.1%.
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Sandra Ronger Savle
39.1 Clinical Presentation The exact incidence of Acanthosis Nigricans (AN) is unknown. In an unselected population of 1412 children, AN were present in 7.1%. In children, it is benign and may be hereditary. In 2000, the American Diabetes Association declared that acanthosis nigricans may be a risk factor for the development of diabetes in children. All forms of this disease, including pseudoacanthosis nigricans, seen in obese patients are now thought to be related to insulin resistance. Related disorders are type 2 diabetes, metabolic syndrome, and polycystic ovarian syndrome. Early recognition of these conditions is essential for prevention of disease progression. Obesity is closely associated with AN, and more than half the adults who weigh more than 200% of their ideal body weight have lesions consistent with AN. In adults, some cases may be linked with malignancy, usually an adenocarcinoma. The malignant form of AN is far less common, and in one study, only 2 of 12,000 patients with cancer had signs of AN. The most frequent associations were with adenocarcinomas of the gastrointestinal tract (70–90%), particularly gastric cancer
S. Ronger Savle (*) Department of Dermatology and Gynecology, Lyon 1 University and Centre Hospitalier Lyon Sud, Pierre Bénite, Lyon, France
(55–61% of malignant AN cases). Approximately, 61.3% of cases are diagnosed simultaneously with the cancer manifestation, while 17.6% of malignant AN cases predate the diagnosis of malignancy. AN may also appear as an adverse effect of medications that promote hyperinsulinemia such as glucocorticoids, niacin, insulin, oral contraceptives, and protease inhibitors. The lesions chiefly affect the neck, the mucosa, and the flexural areas in the groin, knees, and elbows. The genital area is a site of predilection, and the vulva is involved in 5–10%. AN may also affect the eyelids, lips, mucosal surfaces, and dorsal hands. They are dark, at first, velvety, and then warty. We can see papillomatous, brownish-black, and hyperkeratotic plaques. All aspects of the vulva may be involved [1]. While usually asymptomatic, AN is occasionally pruritic.
39.2 Histopathology Histopathology reveals a thickened stratum corneum with minimal involvement of the dermis except for thickened and elongated dermal projections. Despite the term “acanthosis,” the actual amount of acanthosis or thickening of the stratum spinosum is variable and typically mild. The dark color of AN is likely due to hyperkeratosis rather than a mild increase in melanin
© Springer International Publishing AG, part of Springer Nature 2019 J. Bornstein (ed.), Vulvar Disease, https://doi.org/10.1007/978-3-319-61621-6_39
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p igmentation. There is papillomatosis. A subtle infiltrate composed of lymphocytes, plasma cells, or neutrophils may be present, as well as horn pseudocyst formation. Tissue staining with colloidal iron often shows infiltration of the papillary dermis with glycosaminoglycans such as hyaluronic acid, particularly in patients w
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