Case report:
A 52-year-old female presented with a painless right breast lump for one week. On local examination of the breast, the mass measured 6 cm x 4 cm and was located at 12 o’clock position. The overlying skin and nipple-areolar complex were unremarkable. Axillary lymph nodes were not palpable. Initially, the patient was evaluated with a mammogram which showed a lobulated dense mass measuring 49 mm x 48 mm situated in the upper inner quadrant of the right breast (BI-RADS category 4a). Further evaluation with fine-needle aspiration cytology (FNAC) was suggestive of ductal carcinoma. Computed tomography (CT) scan of the chest showed heterogeneously enhancing mass measuring 4.4 cm x 4.3 cm in the upper inner quadrant of the right breast with surrounding perilesional fat stranding and few right axillary lymph nodes with maintained fatty hilum but thick eccentric cortex-likely to be metastatic. (Figure 1)
A diagnosis of ductal carcinoma was made on histopathological evaluation of USG guided tru-cut biopsy. The patient underwent right breast mastectomy with frozen section examination of right axillary sentinel lymph nodes. On frozen section examination, four lymph nodes identified were uninvolved by carcinoma. Gross examination revealed a unifocal tumor located in the upper inner quadrant with the greatest dimension of 4 cm. Histopathological examination revealed tumor cells arranged in diffuse sheets and pseudorosettes. These tumor cells have round to oval nuclei, powdery chromatin with scant cytoplasm. Mitosis and areas of necrosis were noted (Figure2). Further, immunohistochemistry showed tumor cells positive for cytokeratin (CK), focally positive for insulinoma-associated protein 1(INSM-1), cluster of differentiation 56 (CD56), and negative for transcription factor GATA3, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (Her2 Neu) with nuclear protein (Ki67) proliferation of about 40% (Fig. 3).
Based on cumulative information obtained from all the diagnostic procedures including histopathology and immunohistochemistry, the final diagnosis of invasive carcinoma with neuroendocrine differentiation was considered. The pathological stage was pT2 (sn) N0. The postoperative period was uneventful. The patient has received 4thcycle of chemotherapy with Carboplatin and Docetaxel 3 weekly (L1C4 completed) to date. USG of breast, chest X-ray, USG of abdomen and pelvis, and the metabolic panel was performed at 4 months of follow up which showed no evidence of recurrence of the disease.