Question:easy
Identify the organism causing the infection shown on the upper arm.
Identify the organism causing the infection shown on the upper arm.
Show Hint
Name the dermatophytosis by its site: this lesion is on glabrous body skin, not scalp, groin or hand.
Updated On: Jun 23, 2026
- Tinea corporis
- Tinea capitis
- Tinea cruris
- Tinea manus
Show Solution
The Correct Option is A
Solution and Explanation
Spot diagnosis by location: dermatophyte names track the body region they infect. A ring on the trunk or limbs (corpus = body) is Tinea corporis. The image shows exactly that, an annular scaly patch with central clearing and an active erythematous rim on the upper arm.
Quick elimination: capitis = scalp and hair, cruris = groin (jock itch), manus = hand and fingers, pedis = foot. None of these fits an arm lesion, so corporis is the only answer.
Pathology pearl: the fungus stays in dead keratin, but its metabolites diffuse out to inflame the living epidermis, producing the raised vesicular border. Because the leading edge has the live hyphae, scrapings for KOH and culture are taken from the advancing margin, not the cleared centre. Ref: Jawetz Medical Microbiology, 27e, p.668.
Quick elimination: capitis = scalp and hair, cruris = groin (jock itch), manus = hand and fingers, pedis = foot. None of these fits an arm lesion, so corporis is the only answer.
Pathology pearl: the fungus stays in dead keratin, but its metabolites diffuse out to inflame the living epidermis, producing the raised vesicular border. Because the leading edge has the live hyphae, scrapings for KOH and culture are taken from the advancing margin, not the cleared centre. Ref: Jawetz Medical Microbiology, 27e, p.668.
Was this answer helpful?
0
