Sinonasal Secretory Carcinoma of Salivary Gland with High Grade Transformation: A Case Report of this Under-Recognized Diagnostic Entity with Prognostic and Therapeutic Implications

Abstract

Secretory carcinoma (SC) is a recently described salivary gland carcinoma with characteristic ETV6-NTRK3 fusion. In this case report, we described a SC of the maxillary sinus that underwent high grade transformation in a 61-year-old patient. The diagnosis was confirmed by the presence of ETV6 translocation. Within the sinonasal tract, SC is an important differential diagnosis especially of sinonasal adenocarcinoma, non-intestinal type (non-ITAC), as these two entities bears histologic and immunophenotypic similarity. Distinction between these two tumors can be challenging based on the morphology alone and may require additional immunohistochemical and molecular studies. It is important to recognize that SC can occur in the sinonasal tract as correctly diagnosing SC may be prognostic relevant and may provide new targeted therapeutic avenues for these patients.

Keywords: ETV6-NTRK3 fusion; High grade transformation; Secretory carcinoma; Sinonasal non-intestinal type adenocarcinoma.

Fig. 1

Secretory carcinoma (SC) of maxillary sinus (hematoxylin and eosin, a ×100 and b ×400) with high grade transformation (c ×200, d ×400). The maxillectomy contained an infiltrative carcinoma with predominant microcystic pattern. Eosinophilic material was noted within the cystic lumen. The tumor cells were relatively uniform with eosinophilic to clear vacuolated cytoplasm, oval nuclei, vesicular chromatin, and small nucleoli. Areas of solid growth with comedo type necrosis (Ne) and elevated mitotic activity were present multifocally within this tumor, diagnostic of high grade transformation. e–g Immunophemotypically, this tumor was positive for S100, mammaglobin and gross cystic disease fluid protein-15 (GCDFP-15). h Fluorescence in situ hybridization (FISH) demonstrated ETV6 rearrangement (red and green arrows) using ETV6 break-apart probe