Pigmentary Disorders Flashcards
7 cards from real ABD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Pigmentary Disorders flashcards as text
Generalized hyperpigmentation in Addison's disease (primary adrenal insufficiency) is caused by:
Answer: Excess ACTH cross-reacting with MC1R on melanocytes due to loss of cortisol feedback
Loss of cortisol removes negative feedback on the pituitary, causing excess POMC cleavage into ACTH and alpha-MSH; ACTH cross-reacts with the melanocortin-1 receptor (MC1R) on melanocytes, increasing melanin production.
Long-term amiodarone therapy produces a distinctive skin discoloration described as:
Answer: Slate-gray to blue-gray from drug-lipofuscin complexes in dermal macrophages in sun-exposed areas
Amiodarone's iodine content renders it phototoxic; chronic exposure causes iodine-containing drug-lipofuscin complexes to accumulate in dermal macrophages, producing a characteristic slate-gray or blue-gray pigmentation in photoexposed skin.
Which combination of features best differentiates dermal melanocytosis (Mongolian spot) from non-accidental trauma (bruising) in an infant?
Answer: All of the above
Mongolian spots are congenital (present at birth), located characteristically on the lumbosacral region, and show stable blue-gray color without the sequential color change (purple→green→yellow) or swelling that accompanies bruising.
A halo nevus with a depigmented ring surrounding a central benign-appearing melanocytic nevus is best explained by:
Answer: Cytotoxic T-lymphocyte-mediated immune destruction of nevus melanocytes extending to surrounding normal melanocytes
Halo nevi result from a cytotoxic CD8+ T-cell immune response targeting nevus melanocytes that extends to adjacent normal melanocytes, producing a depigmented halo — a mechanism shared with vitiligo.
Progressive macular hypomelanosis is distinguished from pityriasis versicolor by which Wood's lamp finding?
Answer: Folliculocentric red fluorescence in coalescing hypopigmented trunk macules
Progressive macular hypomelanosis shows pathognomonic folliculocentric red fluorescence under Wood's lamp, caused by porphyrins produced by Cutibacterium acnes colonizing follicles, unlike pityriasis versicolor's yellow-green fluorescence.
Idiopathic guttate hypomelanosis is best described as:
Answer: Multiple discrete small porcelain-white macules on chronically sun-exposed extremities of middle-aged and older adults due to focal melanocyte loss
Idiopathic guttate hypomelanosis presents as multiple small, well-demarcated white macules on chronically sun-damaged extremities (shins and forearms) in older adults, caused by focal loss of melanocytes from cumulative UV exposure.
For refractory dermal melasma in a Fitzpatrick skin type IV patient, which laser approach is preferred with the lowest risk of post-inflammatory hyperpigmentation?
Answer: Q-switched Nd:YAG 1064 nm at low fluence (toning protocol)
Low-fluence Q-switched Nd:YAG 1064 nm (toning protocol) penetrates to the dermis to target melanophages with minimal epidermal injury, offering the best safety profile for darker skin types with dermal melasma.