Pleomorphic lobular carcinoma with lipid-producing activity: a report of 2 cases.

This case report presented 2 cases of pleomorphic lobular carcinoma (PLC) of the breast with lipid-producing activity, a type of cancer that has not been previously reported in the literature. The patients were 2 Japanese women aged 67 and 57 years, respectively, who presented with the chief complaint of an indolent tumor mass of the left breast. Both patients underwent breast conserving surgery and axillary sentinel node biopsy. Pathological analysis of breast tissue specimens revealed carcinoma cells, most of which contained abundant granular or foamy cytoplasm, enlarged round nuclei with prominent nucleoli, and intracytoplasmic lumens (ICLs). Digested periodic acid-Schiff (PAS) staining revealed diastase-resistant PAS staining in the ICLs, while Sudan III and oil -red -O staining revealed lipid granules in the cytoplasm. Immunohistochemically, the carcinoma cells from both cases tested negative for E-cadherin but positive for gross cystic disease fluid protein-15, cytokeratin, and mucin 1. Consideration of these findings led to a diagnosis of PLC with lipid-producing activity.