APMLE Dermatology and Nail Disorders 2 — Questions and Answers
Question 1: What is the most appropriate initial treatment for an acute paronychia without abscess formation?
- Oral antifungal therapy
- Warm soaks and topical antibiotics (Correct answer)
- Incision and drainage
- Partial nail avulsion
Correct answer: Warm soaks and topical antibiotics
Early acute paronychia without fluctuance responds to warm water soaks and topical antibiotics; incision and drainage are reserved for cases with abscess formation.
Question 2: A subungual hematoma covering less than 25% of the nail plate in a patient with an intact nail and no distal phalanx fracture is best treated by:
- Nail avulsion and wound exploration
- Trephination (nail decompression) (Correct answer)
- Observation alone
- Oral anticoagulation therapy
Correct answer: Trephination (nail decompression)
Trephination (drilling or heating through the nail plate to drain the hematoma) relieves pain and is appropriate for subungual hematomas regardless of size when the nail is intact.
Question 3: Which clinical feature best differentiates a plantar wart from a corn (heloma durum)?
- Location on the metatarsal head
- Interruption of normal skin lines (dermatoglyphics) (Correct answer)
- Pain with direct pressure
- Presence of a central keratotic plug
Correct answer: Interruption of normal skin lines (dermatoglyphics)
Plantar warts interrupt the normal dermal ridge pattern (skin lines), while corns overlie and compress the skin lines, which is the key distinguishing feature.
Question 4: A nevus (mole) located within the nail unit that causes longitudinal melanonychia should be evaluated carefully because it may represent:
- Subungual exostosis
- Acral lentiginous melanoma (Correct answer)
- Hematoma of the nail bed
- Glomus tumor
Correct answer: Acral lentiginous melanoma
Longitudinal melanonychia with a nail unit nevus raises concern for acral lentiginous melanoma, a serious malignancy disproportionately affecting the nail unit.
Question 5: Which clinical sign (Hutchinson's sign) in nail pigmentation is an indicator of possible subungual melanoma?
- Pale proximal lunula with distal brown discoloration
- Periungual pigmentation extending onto the skin of the proximal or lateral nail folds (Correct answer)
- Transverse white bands across the nail plate
- Uniform darkening of the entire nail plate
Correct answer: Periungual pigmentation extending onto the skin of the proximal or lateral nail folds
Hutchinson's sign refers to pigmentation extending from the nail unit onto the proximal or lateral nail folds, a warning sign associated with subungual melanoma.
Question 6: Which Wood's lamp (UV light) finding is characteristic of tinea versicolor on the skin?
- Bright green fluorescence
- Yellow-green fluorescence
- Copper-orange fluorescence (Correct answer)
- Coral red fluorescence
Correct answer: Copper-orange fluorescence
Tinea versicolor (caused by Malassezia furfur) produces a copper-orange or yellow-gold fluorescence under Wood's lamp examination.
Question 7: Contact dermatitis presenting on the dorsum of the foot with well-demarcated erythema and vesicles in the shape of a shoe is most commonly caused by which allergen?
- Rubber accelerators (thiurams/carbamates) (Correct answer)
- Nickel sulfate
- Formaldehyde resin
- Colophony (rosin)
Correct answer: Rubber accelerators (thiurams/carbamates)
Rubber accelerators (thiurams and carbamates) in shoe insoles and rubber components are the most common contact allergens causing allergic contact dermatitis of the foot.
APMLE Dermatology and Nail Disorders 2
What is the most appropriate initial treatment for an acute paronychia without abscess formation?