OSCE — benign skin lesions: diagnose seborrhoeic keratosis vs concerning lesions and counsel removal options

Brief (to candidate)

A 62-year-old has multiple stuck-on waxy brown facial and truncal lesions increasing with age, plus a firm dimpling nodule on the shin after insect bite years ago, and a rapidly growing friable red nodule on the finger that bleeds. You have 8 minutes to diagnose each pattern, exclude melanoma/SCC concerns, and plan management.

Candidate instructions

1. Recognise seborrhoeic keratosis, dermatofibroma, and pyogenic granuloma patterns.
2. State when to biopsy (ugly duckling, ABCDE change, bleeding ulceration atypical).
3. Outline removal options (cryotherapy, shave, excision) matched to lesion.
4. Counsel recurrence and scarring.
5. Safety-net new/changing pigmented lesions.

Examiner checklist (mark each domain / 10)

Model key actions

• Diagnose classic seborrhoeic keratoses as benign stuck-on lesions; treat only if needed.^[3]
• Identify dermatofibroma with dimple sign; pyogenic granuloma as bleeding vascular growth needing procedural care/histology as indicated.^[5][6]
• Biopsy any lesion with melanoma/SCC uncertainty rather than freeze-and-forget.^[2]

Common errors

• Freezing a suspicious pigmented lesion without histology.
• Calling all stuck-on lesions SK without checking for melanoma mimic.
• Excising without discussing scar.
• Missing pyogenic granuloma vs amelanotic melanoma risk discussion.
• No safety-net for changing pigmented lesions.