Primary Squamous Cell Carcinoma of the Breast: Diagnostic Challenges and Therapeutic Insights From a Rare Case

Abstract

Primary squamous cell carcinoma (SCC) of the breast is a rare type of cancer, representing between 0.06% and 0.2% of malignant breast tumours. The disease presents with rapid growth and an aggressive pattern, and the lack of well-defined therapeutic protocols hinders its treatment. The following is a case report of a 64-year-old female patient presenting with a large nodule in her left breast (>10 cm) with rapid and progressive growth and palpable ipsilateral axillary lymph nodes. The histopathological examination of the core biopsy of the lesion showed a poorly differentiated carcinoma and was clinically staged as an inflammatory carcinoma (T4d N1 Mx). The patient was referred for neoadjuvant chemotherapy with paclitaxel and carboplatin, but showed a poor response with tumor progression, and was referred for hygienic mastectomy surgery. The histopathological result of the surgical specimen showed an invasive carcinoma with squamous differentiation, grade 3, ulcerated, with invasion of the pectoralis muscle and free margins (pT4b pNx pMx). Only after immunohistochemistry of the surgical specimen was it possible to confirm the definitive diagnosis of keratinising squamous cell carcinoma (SCC). Postoperatively, the patient returned with signs of surgical wound dehiscence and pleuropulmonary and mediastinal metastatic progression. After multidisciplinary and family discussion, exclusive palliative care was instituted. Primary squamous cell carcinoma (SCC) of the breast typically manifests rapidly and aggressively, and its diagnosis is quite challenging, requiring histopathological confirmation and, primarily, immunohistochemistry. The gold standard treatment includes breast surgery with clear margins, but there is no consensus regarding adjuvant chemotherapy. Its prognosis is usually guarded, especially in locally advanced or metastatic cases.