Primary Nonkeratinizing Squamous Carcinoma of Breast With Ipsilateral Axillary Lymph Node Metastasis: A Case Report

Abstract

Primary squamous carcinoma is a rare type of metaplastic carcinoma of the breast, incidence being less than 0.1% of all breast carcinomas. The non-keratinizing variant can mimic several rare types of breast carcinomas, prognosis and therapeutic modalities of which are dissimilar. Histopathological examination is gold standard in diagnosing these tumors. Accurate diagnosis employing special stains and immunohistochemistry is mandatory as they are triple negative unlike infiltrating ductal carcinoma NOS, and have aggressive course, poor prognosis and distinctive treatment modalities. Other unique features include less frequent axillary nodal metastasis and necessity to rule out metastatic squamous carcinomas to the breast from other primary sites in these patients. We present a 60 years old lady with a hard lump in the left breast, with no significant past history. Physical examination was suggestive of carcinoma of breast with axillary lymphadenopathy. Histopathological examination revealed squamous carcinoma of breast positive for p63 and cytokeratin (CK) 5/6. Her chest X-ray, abdominal ultrasonography, oral cavity, laryngobronchoscopy, cystoscopy and cervical Pap smears were unremarkable ruling out the possibility of primary squamous tumor in other common organs. KEYWORDS: Metaplastic carcinoma, non-keratinizing, primary squamous carcinoma, squamous carcinoma of breast. INTRODUCTION:The incidences of primary squamous carcinoma of the breast vary between 0.1% to less than 0.04% of all breast carcinomas. 1-3 'Squamous carcinoma of the breast' refers to a tumor in which more than 90% of the neoplastic cells are squamous. 4 'Pure squamous' carcinomas show only squamous cells. 4 The term 'primary squamous carcinoma' of breast is used when the possibility of metastatic squamous carcinoma is ruled out. 4 Immunohistochemistry and special stains differentiate non-keratinizing squamous carcinoma from its histological mimics. These are very aggressive, treatment refractory tumors with poor prognosis. 3 The modalities of therapy also vary as they are hormone receptor negative. 3 CASE REPORT:A 60 years old post-menopausal woman presented with a painless lump in the left breast since 6 months. There was no history of nipple discharge or skin ulceration. There was no significant past history.Physical examination revealed a hard fixed mass in the upper outer quadrant of left breast measuring 4x3cm. The nipple was retracted. Fine needle aspiration cytology of the lesion revealed carcinoma of breast (Figure 1b). She underwent modified radical mastectomy with axillary clearance.Grossly, the tumor measured 4x2.5cm. The cut surface showed areas of necrosis and cystic change. There were no chondroid or osseous areas. The tumor was completely separate from the adjacent skin, nipple and areola (Figure1a). Six axillary lymph nodes were retrieved.