Searching for Mammary Analog Secretory Carcinoma of Salivary Gland Among Its Mimics

Andre Pinto; Vania Nosé; Claudia Rojas; Yao-Shan Fan; Carmen Gomez-Fernandez


Mod Pathol. 2014;27(1):30-37. 

In This Article

Materials and Methods

All cases of acinic cell carcinoma, adenocarcinoma NOS, and cribriform cystadenocarcinoma of salivary gland origin, from three institutions (Jackson Memorial Hospital, Sylvester Comprehensive Cancer Center, and University of Miami Hospital) over a 10-year period, were retrieved. A total of 27 cases were identified, including 11 cases of acinic cell carcinoma, 10 cases of adenocarcinoma NOS, and 6 cases of cribriform cystadenocarcinoma.

Hematoxylin and eosin stained slides were reviewed, and tumors that morphologically resembled mammary analog secretory carcinoma according to the recent literature were selected. Those features included epithelial cells with abundant vacuolated cytoplasm, minimal nuclear pleomorphism, papillary, and microcystic architecture with cellular hobnailing and eosinophilic secretions (Figure 1).

Figure 1.

Mammary analogue secretory carcinoma (MASC) of the parotid gland showing large epithelial cells with plump, eosinophilic cytoplasm arranged in a microcystic pattern of growth (a). Solid sheets of tumor cells can also be seen (b). Bland, vesicular nuclei are characteristic, as well as hobnailing of the cells (c). At higher magnification, a bubbly cytoplasm is noticeable, and pale pink secretion is easily identified within the microcystic spaces (d). a: x100 original magnification, b: x100 original magnification, c: x200 original magnification, d: x400 original magnification. All images are hematoxylin and eosin (H&E).

This process narrowed down the initial number to 10 cases (6 acinic cell carcinomas, 3 adenocarcinomas, NOS, and 1 cribriform cystadenocarcinoma) on which S-100, mammaglobin and ANO1 (DOG1) immunostains were performed ( Table 1 ). Immunohistochemistry was performed using Dako antibodies in 5-μm paraffin-embedded tissues using appropriate tissue-positive controls. All immunohistochemical staining was performed on automatic stainers using antibody dilutions previously determined by pathologists during antibody validation, after appropriate antigen retrieval. Antigen retrieval was performed in a pre-treatment station using both low pH (pH 6, citrate buffer) and high pH (pH 9, EDTA buffer) environments. Staining detection was carried out using a modified biotin–streptavidin–horseradish peroxidase method (Figure 2).

Figure 2.

Immunohistochemical profile of the MASC cases identified in this study. All tumors were immunoreactive for S-100, which in this example had strong and diffuse staining (a). Mammaglobin (MMG) is positive in MASC, as this entity represents the salivary gland counterpart of the breast carcinoma (b). DOG1, a marker for acinic cell differentiation, is negative in MASC. Notice the remaining non-neoplastic acini with the typical intercalated duct staining in the upper left corner (c). All figures: immunohistochemical stains; x200 original magnification.

FISH analysis for the characteristic t(12;15) (p13;q25) with ETV6-NTRK3 fusion was performed using slides prepared from formalin-fixed paraffin-embedded tissues with 3-μm-thick sections. A dual color ETV6-NTRK3 break-apart FISH probe (Abbot Molecular, Des Plaines, Illinois, USA) was used to detect translocation and copy number changes of the ETV6-NTRK3 gene. FISH was performed using a protocol recommended by the manufacturer of theDNA probe. The major steps included slide deparaffinization, codenaturation of probe DNA and tissue materials on slides, hybridization, post hybridization washes, and counterstaining with DAPI. Hybridization signals were analyzed with a fluorescence microscope equipped with a Cytovision system for image capturing and storage (Applied Imaging Corp, USA). For each case, 200 cells were analyzed with result described using the standard cytogenetics nomenclature (ISCN, 2009).[14]