Case Report Primary small cell carcinoma of the breast with TTF-1 and neuroendocrine marker expressing carcinoma in situ
Michael Christie, Laura Chin-Lenn, Monique M. Watts, Alpha E. Tsui, Malcolm R. Buchanan
Departments of Anatomical Pathology, Surgery and 3Medical Oncology, Royal Melbourne Hospital, Victoria, Australia
Received April 21, 2010, accepted April, 2010, available April, 2010
Abstract: Primary small cell carcinoma (SmCC) of the breast is very rare and may be difficult to distinguish from metastatic small cell carcinoma. Confident histopathological diagnosis of a primary breast SmCC requires the demonstration of an in situ component. We report a case of primary small cell carcinoma of the breast with coexisting carcinoma in situ in which the invasive carcinoma and in situ component both expressed neuroendocrine markers and Thyroid transcription factor-1 (TTF-1) by immunohistochemistry. Expression of neuroendocrine markers and TTF-1 in the in situ component allowed a highly confident diagnosis of primary small cell carcinoma of the breast. To our knowledge there is only one previous report of TTF-1 expressing in situ carcinoma associated with a primary SmCC of the breast.(IJCEP1004004).
Key words: Small cell carcinoma, breast, thyroid transcription factor-1, neuroendocrine, carcinoma in situ