Genodermatoses and Nevi Flashcards

Neurofibromatosis type 1 is caused by a mutation in which gene?

Answer: NF1 (neurofibromin)

NF1 results from loss-of-function mutations in the NF1 gene encoding neurofibromin, a RAS-GTPase-activating protein.

Which diagnostic criterion requires at least six lesions greater than 5 mm (prepubertal) in neurofibromatosis type 1?

Answer: Café-au-lait macules

Six or more café-au-lait macules >5 mm prepubertal (>15 mm postpubertal) is a hallmark NIH diagnostic criterion for NF1.

Ash-leaf macules (hypopigmented spots best seen with Wood lamp) are an early sign of which genodermatosis?

Answer: Tuberous sclerosis complex

Ash-leaf (lance-ovate) hypopigmented macules are one of the earliest cutaneous findings in tuberous sclerosis complex.

The facial angiofibromas of tuberous sclerosis were historically misnamed as what?

Answer: Adenoma sebaceum

The angiofibromas of tuberous sclerosis were long called 'adenoma sebaceum,' a misnomer since they are not of sebaceous origin.

A collagenous connective tissue nevus presenting as a leathery plaque over the lumbosacral area in tuberous sclerosis is called a:

Answer: Shagreen patch

The shagreen patch is a connective tissue nevus (collagenoma) classically located on the lower back in tuberous sclerosis.

Periungual fibromas (Koenen tumors) around the nails are a diagnostic feature of which condition?

Answer: Tuberous sclerosis complex

Koenen tumors are periungual/subungual fibromas that typically appear in adolescence in tuberous sclerosis.

Bilateral vestibular schwannomas are the hallmark of which neurocutaneous disorder?

Answer: Neurofibromatosis type 2

Bilateral acoustic (vestibular) schwannomas define neurofibromatosis type 2, caused by NF2/merlin mutations.