Primary Signet-Ring Cell (Mucin-Producing) Adenocarcinoma of Minor Salivary Glands: A Clinicopathologic, Immunohistochemical and Molecular Survey
Jassem M Bastaki, Bibianna M Purgina, Sanja Dacic, Raja R Seethala. University of Pittsburgh Medical Center, Pittsburgh, PA
Background: Primary salivary signet-ring cell (mucin-producing) adenocarcinomas (SRCA) are extremely rare and poorly understood. We evaluate the clinicopathologic features of 4 cases and evaluate immunohistochemical and molecular features modeled after common profiles in mucinous/signet ring adenocarcinomas of other sites.
Design: Four cases were retrieved. Histochemical and IHC staining using standard technique was performed and included the following: mucicarime, PASD, AE1/3, CK7, CK20, CK5/6, CAM 5.2, CDX2, ER, AR, PSA, TTF-1, thyroglobulin, mammaglobin, HER2/neu, synaptophysin, chromogranin, actin, AMA, p63, calponin, PsAP, s100, GCDFP, Ki-67 and E-Cadherin. Additionally, fluorescence in situ hybridization for ALK gene rearrangements using a break apart probe 2p23 was performed (Abbott Molecular, Des Plaines, IL). Cases with more than 20% of tumor cells showing a rearrangement were considered positive.
Results: The male:female ratio was 3:1. The mean age was 56 (range: 18-81). Sites involved were buccal mucosa (2), soft palate (1), and deep parotid (1). Perineural and angiolymphatic invasions were present in (3) and (2) cases respectively. The patient with a soft palate tumor had nodal metastasis on presentation. One patient was lost to follow-up, and the remainder, were alive and without disease at time of last follow up (mean 38 months). All cases showed a uniformly univacuolar (signet ring) appearance embedded in a myxoid stroma and were mucicarmine positive. The IHC profile is summarized in Table 1. Three cases showed at least focal p63 staining, and 2 cases were positive for calponin and GCDFP-15. Interestingly, membranous E-cadherin was retained and mammaglobin was positive in all cases. All tumors were negative for ALK rearrangements.