Atypical diabetic foot ulcer turning into squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) may rarely arise in chronic diabetic foot ulcers, particularly at unusual sites. We report an 86-year-old man with a chronic retrocalcaneal ulcer refractory to standard care. Vascular imaging showed peripheral arterial disease, and biopsy confirmed well-differentiated cSCC (AJCC 8th edition: pT2Nx), measuring 2.1 × 1.5 cm with 8 mm invasion depth. Staging positron emission tomography/computed tomography and magnetic resonance imaging showed no evidence of metastasis. The patient underwent vascular optimization, wide local excision with clear margins, and local advancement flap coverage. At 4 months, there was no recurrence or metastasis, and wound healing was durable. To the best of our knowledge, this is the first reported case in Saudi Arabia of cSCC developing from a diabetic foot ulcer in the retrocalcaneal region. This case underlines the importance of early biopsy and multidisciplinary evaluation in atypical, non-healing ulcers to avoid delayed diagnosis and ensure optimal patient outcomes.