Primary Squamous Cell Carcinoma of the Breast: A Rare Clinical Entity with Diagnostic and Therapeutic Challenges

Primary Squamous Cell Carcinoma (PSCC) of the breast is an exceptionally rare and aggressive malignancy, often lacking welldefined clinical and radiological hallmarks. A 51-year-old postmenopausal woman arrived in septic shock with a necrotic, ulcerative mass in the upper outer quadrant of the right breast, initially misinterpreted as a chronic abscess. Imaging revealed a heterogeneous breast lesion with axillary lymphadenopathy and no distant metastasis. An emergency toilet mastectomy was performed due to progressive sepsis, followed by Vacuum-Assisted Closure (VAC) and split-thickness skin grafting. Histopathology confirmed highgrade squamous cell carcinoma with a minor ductal component (<10%). Immunohistochemistry demonstrated triple-negative receptor status, diffuse nuclear p63 positivity, positivity for CK6 and CK7, and a high Ki-67 index, fulfilling the diagnostic criteria for PSCC proposed by Macia et al. The patient remained disease-free at one-year follow-up after adjuvant radiotherapy. This case underscores the importance of recognising atypical infectious presentations of breast tumours and integrating clinical, radiologic and pathologic findings to distinguish PSCC from close differentials, including chronic abscesses, metastatic carcinomas and other inflammatory breast pathologies.