A 58-year-old man with a draining sinus over the tibia from chronic osteomyelitis of 20 years duration notices that the sinus margin has become a raised, everted, indurated ulcer that bleeds on touch. Biopsy of the edge is taken. The most likely histological finding is:
- A Well-differentiated squamous cell carcinoma ✓
- B Basal cell carcinoma
- C Chronic granulation tissue with plasma cells
- D Malignant fibrous histiocytoma
Correct answer: A. Well-differentiated squamous cell carcinoma
Explanation
Malignant transformation of a long-standing chronic osteomyelitis sinus tract into squamous cell carcinoma, a Marjolin-type change, is a well-recognised complication. Any old sinus that changes character, becomes everted, rolled, or friable, demands biopsy. Basal cell carcinoma arises in sun-exposed skin rather than sinus tracts, and granulation tissue would not produce an everted, indurated, bleeding edge.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.