Neutrophilic emperipolesis in micropapillary carcinoma breast

Abstract

A 38‐year‐old lady presented with a history of a lump in the right breast for 2‐month duration. Examination revealed a 1.5 × 1 × 0.5 cm hard lump in the upper outer quadrant with palpable axillary lymph nodes. Mammography showed an irregular dense lesion having in‐ distinct margins with microcalcifications. The patient underwent a breast conservation surgery with axillary dissection. The histology showed the presence of an infiltrating tumor with neoplastic cells ar‐ ranged in multiple varying sized morula‐like clusters separated from the stroma by a clear space (Figure 1). The individual tumor exhibited reverse polarity, indicative of a micropapillary pattern. Also evident in most of the tumor cells was the presence of neutrophils within the tumor cell cytoplasm indicative of a cell‐in‐cell phenomenon or emperipolesis (Figure 2). Closer examination showed the neutro‐ phils to be surrounded by a halo within the tumor cell cytoplasm. The tumor cells displayed marked nuclear pleomorphism with coarse chromatin, prominent nucleoli, and scant eosinophilic cytoplasm. Immunohistochemistry with epithelial membrane antigen (Clone E29, Dako) showed abluminal staining pattern of tumor cells, with the absence of staining for estrogen receptor (Clone SP1, Roche Ventana), progesterone receptor (Clone 1E2, Roche Ventana), and Her2Neu (Clone 4B5, Roche Ventana). Four lymph nodes showed the presence of metastases. A diagnosis of invasive micropapillary carcinoma was offered. The patient was managed with postsurgery chemoradiotherapy as per guidelines. The lady was symptom‐free at the end of 6 months. Cell‐in‐cell form is characterized by the presence of viable tar‐ get cells which have been internalized within a host cell. Cell‐in‐cell differs from phagocytosis in being encountered in host cells with‐ out known phagocytic function. Depending on the scenario, the engulfed target cell may move within the host cell, undergo divi‐ sion, or escape from the internalized state. Emperipolesis is a type of cell‐in‐cell form which is used as an exercise for the target cell to enter, move within, and exit the host cell. The classic example of which is Rosai–Dorfman disease. There have also been documented