Analysis of clinicopathologic features and expression of NR4A3 in sinonasal acinic cell carcinoma.

Acinic cell carcinoma (AiCC) in the nasal cavity and paranasal sinuses has rarely been reported in literature. A recent study demonstrated that recurrent genomic rearrangement [t(4;9) (q13;q31)] is a driver event in AiCC of the salivary glands that could promote the upregulation of transcription factor nuclear receptor subfamily 4 group A member 3 (NR4A3). In the current study, we evaluated the clinicopathological characteristics and expression of NR4A3 in four new cases of sinonasal AiCC. All four patients were men (range, 27-70 years). The tumor involved only the nasal cavity in two patients, while the other two patients showed involvement of both the nasal cavity and ethmoid sinus. Histologically, the tumor displayed a predominantly solid growth pattern and was composed of hematoxyphilic serous-like cells and scattered intercalated duct-like cells. Immunohistochemically, all cases expressed DOG-1. However, staining for mammaglobin, S-100, CA9, and P63 was absent in all patients. All four cases showed positive nuclear staining for NR4A3. In contrast, none of the other 39 sinonasal tumors, including secretory carcinomas, pleomorphic adenomas, mucoepidermoid carcinomas, adenoid cystic carcinomas, renal cell-like adenocarcinomas, intestinal-type adenocarcinomas, non-intestinal-type adenocarcinomas, extraskeletal myxoid chondrosarcoma, and carcinoma ex pleomorphic adenomas, presented with any positive NR4A3 nuclear staining. Additionally, NR4A3 rearrangements were observed in three cases with sinonasal AiCC by fluorescence in situ hybridization, and the expression level of NR4A3 mRNA was significantly increased in sinonasal AiCC compared with that in normal parotid tissue. Our study demonstrated that sinonasal AiCCs are characterized by an indolent nature and histopathological similarity to parotid AiCCs. Moreover, NR4A3 is a reliable biomarker for distinguishing sinonasal AiCCs from other sinonasal carcinomas.