Melanoma and keratinocyte skin cancer detection — KFP-style written assessment

KFP 1 (10 marks)

A 61-year-old man presents with a firm pink nodule on his right shoulder blade that his wife noticed eight weeks ago. It has grown visibly since. It is not pigmented. His brother had a melanoma removed from his back at 55. ^[8]

1. What is the working diagnosis and why does its appearance not reassure? (3) ^[8]
2. State the correct biopsy — technique, margins, orientation. (4) ^[3]
3. The locum last year froze 'another pink spot' on his back. How do you handle that history? (3) ^[8]

Model answers

1. Nodular melanoma until proven otherwise. Nodular lesions are frequently amelanotic and grow over weeks to months — they violate the slow-changing-mole model that patients and clinicians expect, which is precisely why they present thicker. Family history raises pretest probability further; delay analysis shows the major component is patient-side lack of concern, and men's lesions are more often detected by family members — his wife did exactly what education asks. ^[8]
2. Excision biopsy: 2 mm lateral clinical margins around the lesion, deep to subcutaneous fat, oriented longitudinally so any re-excision is straightforward. Never shave or partially sample a suspected melanoma — partial sampling loses Breslow depth and margin status and risks understaging the tumour. ^[3]
3. A previously frozen unbiopsied pigmented or pink lesion is an unexamined diagnosis. Ask what it was called and whether it recurred; recurrence after destruction warrants biopsy of the scar. Use it as the teaching point: cryotherapy belongs to confirmed benign lesions such as actinic keratoses, never to undiagnosed suspicious lesions. ^[8]