The following are true about acanthosis nigrans except
Correct Answer: It is autosomal recessive
Description: Acanthosis nigricans is a condition marked by thickened, hyperpigmented skin with a “velvet-like” texture that most commonly appears in the flexural areas (axillae, skin folds of the neck, groin, and anogenital regions). It can be an important cutaneous marker of benign and malignant conditions and, accordingly, is divided into two types. The benign type, which constitutes about 80% of all cases, develops gradually and usually occurs in childhood or during puberty. It may occur (1) as an autosomal dominant trait with variable penetrance, (2) in association with obesity or endocrine abnormalities (particularly with pituitary or pineal tumors and diabetes), and (3) as part of several rare congenital syndromes. As with seborrheic keratoses, acanthosis nigricans sometimes occurs as a paraneoplastic process resulting from the production of growth factors by a variety of tumors. The malignant type refers to lesions arising in middle-aged and older individuals in association with underlying cancers, most commonly gastrointestinal adenocarcinomas. The epidermis and underlying enlarged dermal papillae undulate sharply to form numerous repeating peaks and valleys. Variable hyperplasia may be seen, along with hyperkeratosis and slight basal cell layer hyperpigmentation (but no melanocytic hyperplasia). The familial form is associated with germline activating mutations in FGFR3; depending on the mutation, acanthosis may be an isolated finding or be seen together with skeletal deformities, including achondroplasia and thanatophoric dysplasia.
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