Abstract

AIM--To investigate tumour in an axillary lymph node resembling micropapillary ductal carcinoma in situ. METHODS--Sections of tumour in the breast and axillary lymph node were stained with haematoxylin and eosin, and immunohistochemically with antibodies to basement membrane and myoepithelial cells. RESULTS--Tumour in both the breast and axillary lymph node contained areas resembling micropapillary ductal carcinoma in situ. Surrounding these islands, there was a band of eosinophilic material resembling basement membrane and spindle cells that in places appeared to lie outside the basement membrane. Micropapillary tumour at both sites showed weak and discontinuous staining for collagen IV and laminin. The spindle cells stained for alpha-smooth muscle actin, but not for S100. By contrast, immunohistochemistry showed complete rings of basement membrane and myoepithelial cells around definite ductal carcinoma in situ and normal breast lobules and ducts. CONCLUSIONS--Invasive primary and metastatic carcinoma of the breast can have a growth pattern resembling micropapillary ductal carcinoma in situ.