Onkológia 1/2020

Uncommon breast tumours – a pathologist´s view

Uncommon breast tumours include extremely rare breast cancers with unusual and unique cytomorphological or functional characteristics that make them different from other more common breast tumours. These are carcinomas with a./ unusual cellular forms - pleomorphic ductal carcinoma, cancers with chorionic, melanocytic, oncocytic and sebaceous features, and carcinoma with osteoclast-like giant cell in the stroma; b./ accumulating pathological substances in the cytoplasm

• carcinoma rich in lipids or glycogen; c./ cytomorphological features similar to salivary gland carcinomas – acinic cell, mucoepidermoid and polymorphic carcinoma; d. / hypersecretory phenotype - secretory and cystic hypersecretory carcinoma; and e./ phenotypic similarities to tumours of other organs - lymphoepithelium-like carcinoma and breast cancer resembling a tall cell papillary thyroid carcinoma variant. These tumours are described in the literature only in the form of case reports or small colections and represent rare phenotypic entities with considerably limited knowledge of their biological behaviour. Some of these tumours have not yet been included in the World Health Organization classification of the breast tumours (2012), e.g. cystic hypersecretory carcinoma, lymphoepithelioma-like carcinoma, and carcinoma with tall cell-like variants of the papillary thyroid carcinoma.

Keywords: breast, extremely rare tumours, unusual types, carcinoma variants