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10 April 2013 - Case of the Week #271
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Thanks to Dr. Jessica Kozel, University of Nebraska Medical Center, for contributing this case and the discussion. To contribute a Case of the Week, follow the guidelines on our Case of the Week page.
(1) Thanks to Dr. Grace C. Yang for contributing images of papillary thyroid microcarcinoma and Hurthle cell tumors.
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Case of the Week #271
A 61 year old woman presented with a mammographic left breast mass. An incisional biopsy was performed.
What is your diagnosis?
Adenoid cystic carcinoma of the breast
CD117+ staining in this case is indicated below:
Adenoid cystic carcinoma is a rare breast tumor (0.1% of breast carcinomas, Ann Surg Oncol 2013 Mar 1 [Epub ahead of print]), and identical to its salivary gland counterpart. Other salivary gland-like tumors of the breast include mucoepidermoid carcinoma and acinic cell carcinoma.
Adenoid cystic carcinoma has cribriform, solid, trabecular and basaloid patterns, two types of cavities and two types of cells. True glandular lumina are lined by ductal epithelium (EMA+, keratin+, CD117+, Mod Pathol 2005;18:1623) and eosinophilic “cylinders” with basement membrane material are lined by basal / myoepithelial-type cells (p63+, S100+, smooth muscle actin+, vimentin+). Secretions in the true lumina are PAS+ diastase resistant, and cribriform spaces are Alcian blue+. All salivary gland tumors of the breast, including adenoid cystic carcinoma, are characteristically negative for ER, PR, and HER2 (triple negative), and express basal cell markers CK5/6, P-cadherin and p63 (Appl Immunohistochem Mol Morphol 2012 Aug 29 [Epub ahead of print]). The MYB-NFIB fusion gene [t(6;9)(q22-23;p23-24)] has been found in some breast adenoid cystic carcinomas (J Pathol 2012;226:84).
The differential diagnosis includes collagenous spherulosis, a rare, benign disorder of intraluminal clusters of eosinophilic or rarely basophilic collagen-rich spherules within spaces, surrounded by flattened myoepithelial cells. Collagenous spherulosis typically occurs in proliferative lesions, and is usually incidental, unlike the present case which presented as a mass.
Cribriform carcinoma, either in situ or invasive may have similar morphology, but only has one cell type. In contrast to adenoid cystic carcinoma, it is ER+, PR+, p63- and CD117-.
Treatment of adenoid cystic carcinoma of the breast is excision with clear margins, and possibly radiation. Axillary nodal metastases are rare, so axillary dissection may not be necessary. It has a good to excellent prognosis, better than at other locations, with high rates of positive margins, but less recurrence or metastases than usual ductal carcinoma.
Nat Pernick, M.D., President
and Palak Thakore, Associate Medical Editor
30100 Telegraph Road, Suite 408
Bingham Farms, Michigan (USA) 48025
Alternate email: NatPernick@gmail.com