Infections & Infestations (incl. regional)

A 6-year-old boy has honey-colored crusts around the nostrils without fever. First-line treatment?

A 3-year-old develops flaccid bullae on trunk; cultures grow S. aureus producing exfoliative toxin. Best therapy?

A 35-year-old fisherman has sharply demarcated, fiery-red facial plaque with fever following minor cheek abrasion. Diagnosis and step?

A 52-year-old with recurrent cellulitis of the leg also has interdigital scaling and maceration between toes. Key preventive measure?

After hot-tub exposure, a 20-year-old develops widespread pruritic papulopustules in swimsuit distribution. Best management?

A landscaper develops a painless, ulcerated nodule on forearm with lymphangitic spread of subcutaneous nodules. Most likely and treatment?

A 28-year-old with intensely pruritic serpiginous track on plantar foot after beach trip. Best therapy?

A 4-year-old with scalp scaling, alopecia patches, and posterior cervical nodes. Best treatment?

A 33-year-old has annular scaly plaque with active border and central clearing on thigh; KOH positive for hyphae. First-line?

A 40-year-old with folliculocentric pustules on back and chest fails repeated oral antibiotics; KOH shows budding yeast. Diagnosis/therapy?

A 25-year-old with crusted, hyperkeratotic widespread scabies and nail involvement; lives in nursing facility. Best regimen?

A mother asks how to manage contacts for classic scabies in her child. Correct advice?

A 30-year-old woman in first trimester has generalized pruritus with nocturnal exacerbation, burrows on wrists/finger webs. Best treatment?

After successful scabies treatment, pruritus persists for 3 weeks without new burrows. Explanation?

A 7-year-old with pediculosis capitis; family asks best first-line.

A 24-year-old with multiple dome-shaped, umbilicated papules on thighs/genitals; mild eczema around lesions. Best management?

A 36-year-old diabetic with rapidly progressive painful erythematous skin, violaceous bullae, crepitus, and systemic toxicity. Next best step?

A neutropenic patient develops painless black necrotic ulcers with surrounding erythema on the trunk; blood cultures pending. Likely pathogen and step?

A 29-year-old woman with recurrent painful nodular lesions in hair-bearing labia majora diagnosed as furunculosis; culture MRSA. Best outpatient therapy?

A 55-year-old with sharply demarcated brown-red patches in groin; Wood lamp shows coral-red fluorescence. Best treatment?

A 34-year-old with a chronic crusted painless papule on forearm acquired after travel to the Middle East; smear shows intracellular amastigotes. Best therapy?

A 26-year-old pregnant woman with suspected cutaneous leishmaniasis (PCR positive). Preferred management?

A 49-year-old man with anesthetic hypopigmented patch on elbow, thickened ulnar nerve, and reduced pinprick sensation. Most likely diagnosis?

A patient with leprosy develops tender subcutaneous nodules, fever, and malaise during treatment (ENL). Best acute management?

A hyperpigmented, scaly macular eruption on trunk; KOH shows “spaghetti and meatballs.” First-line?

A 60-year-old with painful vesicles in trigeminal V1 distribution and eye redness. Immediate management?

A 22-year-old with recurrent “cold sores” worsened by sun exposure. Best suppressive strategy?

A 45-year-old with onychomycosis of toenails confirmed by KOH. Best systemic therapy and key monitoring?

A 19-year-old with painful vesiculopustular eruption limited to eczematous areas; fever and malaise. Next step?

A 38-year-old with perianal itchy plaques and satellite pustules; KOH positive for pseudohyphae. Best therapy?

A traveler develops painless black eschar with surrounding edema on forearm after handling animal hides. Likely diagnosis?

A 27-year-old man with tinea cruris fails OTC steroids/antifungal combo; lesion worsened with steroid. Best current management?

A 55-year-old gardener with verrucous plaque on leg; biopsy shows pigmented “copper penny” sclerotic bodies. Diagnosis/therapy?

A 30-year-old farmer with chronic draining sinuses and “grains” from plantar foot swelling. Likely condition and first-line?

A sexually active 24-year-old pregnant woman has exophytic anogenital warts. Best management?

A 42-year-old with acute paronychia after nail-biting presents with throbbing pain and erythema. Best next step?

A 60-year-old with green nail discoloration after chronic water exposure and onycholysis. Diagnosis and therapy?

A 22-year-old with tinea barbae from a pet kitten shows inflammatory plaques with pustules on beard area. Best treatment?

A 34-year-old develops nodular lymphangitis after sandfly bites; lesion aspirate shows amastigotes. Best systemic option for complicated disease?

A 48-year-old with painful, foul-smelling plantar pits and hyperhidrosis from occlusive shoes. Most likely and treatment?

A 38-year-old aquarium hobbyist develops violaceous papulonodules along a scratch on the hand with sporotrichoid spread; culture grows photochromogenic mycobacteria. Best treatment?

A 29-year-old wrestler has annular scaly plaques on face and neck; teammates affected. Best initial management?

A 48-year-old fisherman presents with a violaceous, painful plaque on the finger after handling raw fish; no systemic symptoms. Likely pathogen and therapy?

A 7-year-old boy with tender honey-crusted ulcers penetrating into the dermis on shins; regional nodes palpable. Therapy?

A pregnant 26-year-old with erythema migrans after tick bite. Best treatment?

A 55-year-old with a persistent subcutaneous painless nodule on forearm with a central punctum and movement sensation; recently returned from the tropics. Diagnosis/management?

A 9-year-old with intensely pruritic papules in linear clusters on exposed arms after travel; morning examination shows small blood spots on sheets. Likely cause and step?

A 30-year-old with acne on long-term oral antibiotics develops pustular folliculitis by Gram-negative rods. Best next step?

A 40-year-old butcher develops a single umbilicated violaceous nodule on the hand after lambing season; no systemic signs. Most likely?

A 32-year-old with tinea pedis (moccasin type) and unilateral scaly palm (“two feet–one hand” syndrome). Best therapy?

A 65-year-old with recurrent cellulitis of the leg and chronic edema. Preventive strategy besides tinea care?

A 23-year-old diver develops verrucous plaques on the dorsum of the hand after coral injury; KOH negative; culture grows dematiaceous fungi. Diagnosis/therapy?

A 42-year-old with chronic wet work has painful swollen proximal nail folds with transverse nail ridging. Likely and management?

A 36-year-old develops subcutaneous nodules and lymphangitis after thorn injury; smear shows branching filamentous, weakly acid-fast organisms. Best therapy?

A 28-year-old returns from West Africa with a painful papule on the toe with a central black dot; radiograph shows a small intradermal cavity. Diagnosis/management?

A 52-year-old diabetic with interdigital maceration develops malodorous ulcers with green hue and undermined borders on the foot. Best empiric coverage?

A 6-year-old child has high fever then sudden defervescence with rose-pink macules on trunk/neck. Diagnosis?

A 22-year-old college student with fever, malaise, and painful oral ulcers plus targetoid macules on hands/feet after HSV outbreak. Diagnosis/management?

A 35-year-old HIV+ (CD4 90) with multiple molluscum contagiosum on face/eyelids. Best approach?

A 44-year-old gardener has painful nodules and draining sinuses on leg; grains are white-to-yellow and culture grows Nocardia brasiliensis. Diagnosis/therapy?

A 58-year-old with burning grouped vesicles on erythematous base on the chest; Tzanck smear shows multinucleated giant cells. Most appropriate step?

A 27-year-old with papulovesicles and intense itch on finger webs/penile shaft; pink-brown nodules on scrotum persist after therapy. Management for nodules?

A 31-year-old with tender red nodules on shins (panniculitis), recent sore throat, and arthralgia. Most likely diagnosis/next step?

A 47-year-old presents with an enlarging boggy plaque with broken hairs and pustules on the scalp; KOH positive for dermatophyte. Best treatment?