Infectious and Infestation Skin Diseases — WACS Viva & Clinical Scenarios (Dermatology and Venereology)

Exam-style infectious and infestation skin diseases viva scenarios with examiner probes and model answers for Internal Medicine candidates.

Scenarios covered

• SCENARIO 1: A 34-year-old male presents with multiple hypopigmented, anaesthetic macules over his trunk and limbs, associated with bilateral enlargement of the greater auricular and common peroneal nerves. Outline your diagnostic approach, the Ridley-Jopling and WHO operational classifications, and formulate the standard multidrug therapy regimen. Detail the clinical features, immunopathological mechanisms, and management of Type 1 (reversal) and Type 2 (erythema nodosum leprosum) lepra reactions.
• SCENARIO 2: A 28-year-old farmer from a riverine rural community presents with a painless, non-ulcerated, indurated subcutaneous plaque on the right forearm of four weeks duration. Discuss the differential diagnosis, microbiological confirmation, and staging of Mycobacterium ulcerans infection (Buruli ulcer). Detail the WHO-recommended oral antimycobacterial regimen, monitoring for toxicity, and indications for surgical debridement or skin grafting.
• SCENARIO 3: A 45-year-old agricultural worker presents with progressive, chronic, painless swelling of the right foot with multiple discharging sinus tracts exuding black granules. Contrast the clinical, radiological, histological, and microbiological features of actinomycetoma versus eumycetoma. Formulate the comprehensive medical and surgical management plan for both entities.
• SCENARIO 4: A 52-year-old woman with poorly controlled type 2 diabetes presents with acute-onset rapidly spreading erythema, severe pain out of proportion to physical findings, bullae formation, and crepitus along the left lower leg, accompanied by high fevers and hypotension. Discuss the clinical differentiation between erysipelas, cellulitis, and necrotizing fasciitis. Detail the immediate diagnostic workup, risk stratification, empirical antimicrobial choices, and multidisciplinary emergency management.
• SCENARIO 5: A 38-year-old male with advanced HIV disease presents with widespread, heavily crusted, hyperkeratotic, psoriasiform plaques involving the scalp, hands, feet, and generalized body surfaces, accompanied by minimal pruritus. Explain the pathophysiology, diagnostic scrapings technique, and differential diagnosis of crusted (Norwegian) scabies. Detail the institutional infection control protocols, environmental eradication, and combined systemic and topical treatment regimens.