ABD Genodermatoses and Nevi 3

Question 1

Xeroderma pigmentosum results from a defect in which DNA repair pathway?

Accepted Answer

Nucleotide excision repair

Answer

Xeroderma pigmentosum is caused by defective nucleotide excision repair, impairing removal of UV-induced pyrimidine dimers.

Question 2

Patients with xeroderma pigmentosum have a markedly increased risk of what cutaneous complication?

Accepted Answer

Early skin cancers on sun-exposed skin

Answer

Impaired repair of UV damage leads to numerous early basal cell carcinomas, squamous cell carcinomas, and melanomas.

Question 3

Incontinentia pigmenti follows which inheritance pattern and is usually lethal in males?

Accepted Answer

X-linked dominant

Answer

Incontinentia pigmenti (IKBKG/NEMO mutation) is X-linked dominant and typically lethal in affected males in utero.

Question 4

The four sequential stages of incontinentia pigmenti (vesicular, verrucous, hyperpigmented, hypopigmented) follow what distribution?

Accepted Answer

Lines of Blaschko

Answer

The cutaneous lesions of incontinentia pigmenti evolve along the lines of Blaschko reflecting mosaicism.

Question 5

A port-wine stain in the V1 trigeminal distribution with leptomeningeal angiomatosis suggests which syndrome?

Accepted Answer

Sturge-Weber syndrome

Answer

Sturge-Weber syndrome combines a facial capillary malformation (port-wine stain) with ipsilateral leptomeningeal and ocular vascular anomalies.

American Board of Dermatology (ABD) Practice Test