SU18.1-3 | Skin and Subcutaneous Tissue — Assignment

CLINICAL SCENARIO

You are running a surgical outpatient clinic and see three patients in succession. First, a 35-year-old diabetic woman with a hot, tender, fluctuant swelling in the axilla and surrounding redness, having failed a week of oral antibiotics. Second, a 68-year-old fisherman with a slowly enlarging ulcer on the rim of his right ear that has a raised, rolled, pearly edge and has never spread; and on his left forearm an old burn scar that has recently developed a raised, everted, bleeding edge that will not heal. Third, a 50-year-old man who has noticed a 3 cm lump in the front of his neck and is anxious about cancer.

1. The axillary infection — drain or treat medically?

Classify this lesion within the spectrum of skin and soft-tissue infection. State which bedside finding determines that this is a collection rather than diffuse cellulitis, and justify your management. Then describe the warning features that would make you suspect necrotizing fasciitis instead, and what that would change.

Guidance: Use the principle 'where there is pus, let it out' (ubi pus, ibi evacua). Explain that fluctuance indicates pus requiring incision and drainage, and that antibiotics alone do not cure an abscess. List the necrotizing-fasciitis red flags (pain out of proportion, rapid spread, crepitus, systemic toxicity) and that it is a surgical emergency.

2. The ear ulcer and the scar — naming and managing the skin tumours

Classify each of the two lesions (the pearly rolled-edge ear ulcer and the everted non-healing scar edge). Name each likely diagnosis, explain how their natural history and risk of spread differ, and outline the principles of management including margins and the lymph nodes.

Guidance: Identify the ear lesion as a basal cell carcinoma (rodent ulcer) — locally erosive, rarely metastasising. Identify the scar lesion as a squamous cell carcinoma arising in a chronic scar (Marjolin's ulcer) — can spread to regional nodes. State the principle of complete excision with a clear margin and node assessment for SCC.

3. The melanoma rule and prognosis

Briefly explain how you would assess any suspicious pigmented lesion using the ABCDE rule, how you would confirm a melanoma, and which single histological factor most determines prognosis.

Guidance: ABCDE = Asymmetry, Border irregularity, Colour variation, Diameter >6 mm, Evolution. Confirm by excision biopsy; Breslow thickness is the principal prognostic factor and guides re-excision margins; address regional nodes where indicated.

4. The neck lump — a disciplined swelling examination and investigation plan

Describe, in the fixed order you would use, the clinical examination of this neck swelling. Explain what each major special sign would tell you (e.g. fluctuation, movement on swallowing) and why the regional lymph nodes must always be examined. Then set out a rational, stepwise investigation plan and state the principle linking examination to investigation.

Guidance: Follow inspection → palpation → percussion → auscultation → regional nodes. Determine the anatomical plane and tissue of origin first. State that fluctuation = fluid and movement on swallowing suggests thyroid attachment. Emphasise that the regional nodes are examined in every swelling and that investigations follow (not replace) the examination.