OSCE — black-dot foot nodule and furuncular pore: tungiasis vs myiasis vs CLM

Brief (to candidate)

A 34-year-old returns from rural Brazil with two problems: (1) white-yellow nodules with central black dots on the soles after walking barefoot, and (2) a painful scalp nodule with a central breathing pore and a sensation of movement. A friend who stayed on the same beach has a serpiginous itchy track on the foot. You have 8 minutes to separate tungiasis, myiasis, and cutaneous larva migrans and give correct first-line care.

Candidate instructions

1. Map each morphology to the correct ectoparasite.
2. State definitive treatment for tungiasis (extraction + tetanus).
3. State bedside management of furuncular myiasis (occlude then extract — do not simply incise).
4. Treat cutaneous larva migrans with oral anthelmintics.
5. Flag secondary infection / tetanus / cavitary myiasis emergencies.

Examiner checklist (mark each domain / 10)

Model key actions

• Match black-dot foot nodule → extract flea; breathing pore → occlude-extract larva; serpiginous track → anthelmintic.^[1][4][8]
• Cover tetanus and secondary bacterial infection in tungiasis.^[1]
• Do not treat all three the same way (incision/curettage is wrong for CLM and dangerous if done blindly for botfly).

Common errors

• Incising a botfly nodule without occlusion strategy and fragmenting the larva.
• Calling CLM "ringworm" and giving topical antifungals only.
• Ignoring tetanus and footwear advice in tungiasis.

• Missing highly contagious wound myiasis needing debridement in neglected ulcers.
• Assuming ivermectin alone is first-line for a solitary embedded sand flea when mechanical extraction is required.