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Mammary Analogue Secretory Carcinoma of Salivary Glands, Containing the ETV6-NTRK3 Fusion Gene: A Hitherto Undescribed Salivary Gland Tumor Entity

Skálová, Alena MD, PhD* †; Vanecek, Tomas PhD; Sima, Radek MSc; Laco, Jan MD§; Weinreb, Ilan MD; Perez-Ordonez, Bayardo MD, FRCPC; Starek, Ivo MD, PhD; Geierova, Marie MD; Simpson, Roderrick HW. MD**; Passador-Santos, Fabricio MD††; Ryska, Ales MD, PhD§; Leivo, Ilmo MD††; Kinkor, Zdenek MD, PhD; Michal, Michal MD*

American Journal of Surgical Pathology: May 2010 - Volume 34 - Issue 5 - pp 599-608
doi: 10.1097/PAS.0b013e3181d9efcc
Original Articles

We present a series of 16 salivary gland tumors with histomorphologic and immunohistochemical features reminiscent of secretory carcinoma of the breast. This is a hitherto undescribed and distinctive salivary gland neoplasm, with features resembling both salivary acinic cell carcinoma (AciCC) and low-grade cystadenocarcinoma, and displaying strong similarities to breast secretory carcinoma. Microscopically, the tumors have a lobulated growth pattern and are composed of microcystic and glandular spaces with abundant eosinophilic homogenous or bubbly secretory material positive for periodic acid-Schiff, mucicarmine, MUC1, MUC4, and mammaglobin. The neoplasms also show strong vimentin, S-100 protein, and STAT5a positivity. For this tumor, we propose a designation mammary analogue secretory carcinoma of salivary glands (MASC). The 16 patients comprised 9 men and 7 women, with a mean age of 46 years (range 21 to 75). Thirteen cases occurred in the parotid gland, and one each in the minor salivary glands of the buccal mucosa, upper lip, and palate. The mean size of the tumors was 2.1 cm (range 0.7 to 5.5 cm). The duration of symptoms was recorded in 11 cases and ranged from 2 months to 30 years. Clinical follow-up was available in 13 cases, and ranged from 3 months to 10 years. Four patients suffered local recurrences. Two patients died, 1 of them owing to multiple local recurrences with extension to the temporal bone, and another owing to metastatic dissemination to cervical lymph nodes, pleura, pericardium, and lungs. We have shown a t(12;15) (p13;q25) ETV6-NTRK3 translocation in all but one case of MASC suitable for analysis. One case was not analyzable and another was not available for testing. This translocation was not found in any conventional salivary AciCC (12 cases), nor in other tumor types including pleomorphic adenoma (1 case) and low-grade cribriform cystadenocarcinoma (1 case), whereas ETV6-NTRK3 gene rearrangements were proven in all 3 tested cases of mammary secretory carcinoma. Thus, our results strongly support the concept that MASC and AciCC are different entities.

*Department of Pathology, Charles University, Faculty of Medicine

Molecular Pathology Laboratory, Department of Pathology, Medical Faculty Hospital

Bioptic Laboratory, Pilsen

§Department of Pathology, Charles University, Faculty of Medicine and University Hospital, Hradec Kralove

Departments of Otorhinolaryngology

Pathology and Laboratory of Molecular Pathology, University Hospital and Faculty of Medicine, Palacký University Olomouc, Czech Republic

Department of Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada

**Department of Histopathology, Royal Devon and Exeter Hospital, Exeter, England

††Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland

Correspondence: Alena Skálov, MD, PhD, Sikl's Department of Pathology, Medical Faculty of Charles University, Faculty Hospital, E. Benese 13, 305 99 Pilsen, Czech Republic (e-mail: skalova@fnplzen.cz).

Case 1 was presented (AS) at the Slide Seminar SS3 Head and Neck Pathology at the 22nd European Congress of Pathology, in Florence, Italy, September 4-9th 2009.

The preliminary results of the study were also presented at the USCAP Meeting in Washington, DC, USA, March 20-26th, 2010.

Supported by: Grant Nr. 9725 of IGA MH CR (Internal Grant Agency of Health Ministry, Czech Republic).

© 2010 Lippincott Williams & Wilkins, Inc.