A 66-year-old man came to us with a painless mass in his left breast. Upon palpation, the mass was round, well circumscribed, solid, mobile and approximately 1.5 cm in diameter. His axillary lymph nodes were not enlarged. Mammographic examination of his left breast showed a partially infiltrative mass without microcalcifications and with no axillary lymph-node enlargement. These clinical and radiological features were suspicious for malignancy. Although a fine-needle aspiration biopsy showed some cytologic features that suggested malignancy, an excisional biopsy was performed because the clinical and radiological features were unconvincing.
The final histopathology of the biopsy revealed a pure IMPC of the male breast with an intraductal component of not more than 25%, with micropapillary variant. On microscopic examination, the primary distinctive feature of the tumour was the overall nested pattern, in which the nests were surrounded by artificially created clear spaces (). Tumour cells within the nests had either a solid or a tubular configuration. Papillary structures were also seen in small clusters nearly without fibrovascular core.
FIG. 1. Invasive micropapillary breast carcinoma: morule-like clusters of tumour cells within spaces defined by a network of loose fibrocollagenous stroma.
Using the modified Bloom–Scharf– Richardson scoring system, we graded the tumour as poorly differentiated (grade III). In this case, ductal carcinoma in situ was also present and this component showed micropapillary type with a high nuclear grade. During immunohistochemical investigations of the specimen, tumour cells did not stain for estrogen or progesterone receptor (ER, PR), p53 or thyroid transcriptase factor-1 (TTF-1), but results were positive for c-erbB-2 (20% of cells), MIB-1 (60%) and milk fat globulin protein-1 (MFGP-1). Routine chest radiography revealed a metastatic lesion in the right lung. Abdominal CT showed a right adrenal mass supporting distant metastasis. By these findings, the patient was accepted as stage IV breast carcinoma. Adjuvant chemotherapy with CEF (cyclophosphamide 500 mg/m2, epirubicin 100 mg/m2 and 5-fluorouracil 500 mg/m2) was begun. The patient had undergone only 1 cycle of chemotherapy when he died of distant metastases, 3 months after the initial diagnosis.