Tall cell variant of papillary breast carcinoma: an additional case with review of the literature.

Papillary lesions of the breast can be one of the most challenging aspects of mammary pathology because of a wide morphologic spectrum that may be encountered in these lesions. An unusual breast tumor has been first classified as "breast tumor resembling the tall cell variant of papillary thyroid carcinoma" and subsequently renamed "tall cell variant of papillary breast carcinoma". To our knowledge, only 13 cases of this neoplasm have been reported so far. Metastasis to the breast is not an uncommon event and about 5% of all such cases are of the thyroid origin. We report the clinico-pathological and immunohistochemical features, together with a molecular screening for BRAF mutations, of an additional case of tall cell variant of papillary breast carcinoma occurring in a 65-year-old woman. The immunohistochemical and molecular clues leading to the correct diagnosis have been correlated with the data of the literature. Tall cell variant of papillary breast carcinoma represents a unique histologic subtype of mammary carcinoma of probably low malignant potential which has to be recognized to avoid misdiagnosis as metastatic carcinoma from the thyroid.