ABD Pigmentary Disorders 3

Question 1

Incontinentia pigmenti (Bloch-Sulzberger syndrome) progresses through four cutaneous stages in which order?

Accepted Answer

Vesicles/bullae → verrucous → whorled hyperpigmentation (Blaschko's lines) → hypopigmented/atrophic

Answer

Incontinentia pigmenti classically follows four sequential stages: Stage 1 (vesicular/bullous, eosinophilic), Stage 2 (verrucous), Stage 3 (whorled hyperpigmentation along Blaschko's lines from melanin incontinence), and Stage 4 (hypopigmented/atrophic).

Question 2

Which constellation of findings is diagnostic of Waardenburg syndrome?

Accepted Answer

Sensorineural deafness, white forelock, heterochromia iridis, and dystopia canthorum

Answer

Waardenburg syndrome is characterized by sensorineural deafness, white forelock (poliosis), heterochromia iridis, and dystopia canthorum (lateral displacement of inner canthi), caused by mutations in PAX3, MITF, SOX10, EDN3, or EDNRB affecting neural crest melanocyte migration.

Question 3

In a fair-skinned infant suspected of having tuberous sclerosis complex, ash-leaf macules are best detected using:

Accepted Answer

Wood's lamp examination in a darkened room

Answer

Wood's lamp examination in a darkened room accentuates the hypopigmented ash-leaf macules by creating high contrast, making subclinical lesions visible even in fair-skinned infants who may otherwise appear unaffected.

Question 4

Erythema dyschromicum perstans (ashy dermatosis) is best characterized by which description?

Accepted Answer

Gray-brown ('ashy') macules and patches with active erythematous borders in early stages, predominantly affecting individuals with darker phototypes

Answer

Erythema dyschromicum perstans presents as gray-brown ('ashy') hyperpigmented macules and patches with erythematous borders in early active disease, predominantly affecting Hispanic and darker-skinned individuals, and is considered a form of interface dermatitis.

Question 5

Perioral and acral mucocutaneous lentigines in Peutz-Jeghers syndrome result from germline mutations in which gene?

Accepted Answer

STK11/LKB1 (serine-threonine kinase 11) on chromosome 19p

Answer

Peutz-Jeghers syndrome is caused by autosomal dominant germline mutations in STK11 (LKB1), encoding a serine-threonine kinase tumor suppressor on chromosome 19p13, leading to mucocutaneous lentigines and hamartomatous gastrointestinal polyps.

American Board of Dermatology (ABD) Practice Test

American Board of Dermatology (ABD) Practice Test

ABD Pigmentary Disorders 3