SPINDLE-CELL ENDOCRINE CARCINOMA OF THE MAMMARY-GLAND

We report the pathological characteristics of a variant of mammary end ocrine tumour, predominantly formed from cytologically bland spindle c ells. This neoplasm grows as a red, well defined mass lacking the usua l macroscopical characteristics of breast cancer. Within smoothly cont oured aggregates arranged in an insular pattern, delicate capillaries and collagen bundles support the neoplastic epithelial cells. Most of the tumour cells possess a slender spindle shape and form a solid or f enestrated sheet, but a few appear cuboidal and create glands. Immunoh istochemical studies demonstrate that the spindle cells and the glandu lar cells constitute a single population. Both types of cells stain fo r neuroendocrine markers (chromogranin, synaptophysin, and CD 57), car cinoembryonic antigen, keratin 8/18, S-100 protein, and receptors for oestrogen and progesterone. Many of the tumour cells possess argyrophi lic granules, and electron microscopy may reveal dense core granules.