Amphicrine carcinoma of breast with giant granules: an immunohistochemical, histochemical and ultrastructural study.

Abstract

A moderately differentiated grade 2 invasive ductal carcinoma was diagnosed in the right breast of an 81-year-old woman. The uniform nuclear profiles and moderately abundant granular cytoplasm suggested a neuroendocrine tumour and a Grimelius stain was positive. Neurone specific enolase, synaptophysin and somatostatin stained positively, and casein was interpreted as positive although with some background staining. By electron microscopy, tumour cells possessed desmosomes, tonofibrils, intercellular lumina, lamina and dense granules. Rounded dense granules 160-480 nm in diameter resembled neuroendocrine granules. They were found in both luminal and basal areas. Fewer and much larger ('giant') granules had a rounded profile and were up to 5 microm across. The smaller cytoplasmic granules were mostly Grimelius-positive while giant granules were negative. The smaller granules were also uranaffin-positive, but no uranaffin-positive cytoplasmic giant granules were encountered. Both small and giant granules were observed in lumina, and here both were uranaffin-positive. Intraluminal giant granules had a substructure of small pale lipid-like lacunae, and some had irregular profiles. The exceptional size of these exocrine granules is emphasised, and the nature of both the small and giant granules discussed in this amphicrine carcinoma.