Sarcomatoid cutaneous squamous cell carcinoma of the heel: a rare localization of an aggressive variant of cutaneous squamous cell carcinoma

Sarcomatoid cutaneous squamous cell carcinoma (SCSCC) is a rare and aggressive variant of squamous cell carcinoma characterized by spindle-cell morphology resulting from epithelial–mesenchymal transition rather than true biphasic differentiation. Its sarcomatoid component may mimic other spindle-cell neoplasms, making diagnosis challenging. We report a 63-year-old chronic smoker presenting with a giant, rapidly enlarging ulcerated tumour of the left heel, initially misdiagnosed as a callus and later as Kaposi sarcoma and melanoma. Imaging showed no metastasis. The patient underwent wide trans-calcaneal resection with prophylactic inguinal lymph-node dissection. Histology demonstrated a high-grade spindle-cell malignancy expressing epithelial markers (CK5/6, AE1/AE3, p63) with negativity for specific melanocytic markers, confirming SCSCC (pT4N0, AJCC 8th edition). After 3 months of follow-up, no recurrence or metastasis was observed. This case highlights diagnostic pitfalls and the importance of comprehensive immunohistochemistry and multidisciplinary management.