[Amyloid-forming apudoma of the breast]

A peculiar mammary gland tumour is described. Histological structures typical for apudomas of various level of differentiation were combined in the tumour. Apart from highly differentiated carcinoid-like areas, there were zones of a small-cell carcinoma corresponding to a poorly differentiated variant of apudoma. Deposits of amyloid were found in the tumor stroma, this being non-typical for mammary carcinoma. Amyloid was stained by Congo red and birefringent in a polarizing microscope. When differential diagnostics of mammary gland tumours is made, stromal amyloidosis in parallel to typical histological picture and specific histochemical reactions may play a role of an additional diagnostic symptom.