LAUSR

Objetive Present a case of low-grade mucinous sinonasal adenocarcinoma, non-intestinal type in maxillary sinus. The intestinal type sinonasal adenocarcinomas (I-TSAC) are a very rare neoplasm with similar architectural and cytological features to a G.I. metastatic carcinomas; the non-intestinal type cacinomas are less frequent that I-TSAC. Case 70-year-old male with a painless swelling on the zygomatic area, epistaxis and nasal obstruction symptoms with six months of evolution. X-ray examination revealed solid mass occupying the left maxillary antrum, infiltrating the zygomatic arch and the eye orbital floor. The microscopic findings consist in solid-mucionous neoplasm of pleomorphic low columnar cells, the cellular proliferation was arranged in nest with back to back architectural growth pattern, and focal bone invasion, A very loose eosinophilic stroma with mucinous aspect surround the neoplastic nests. Immunohistochemical reactions was positive for CK7, and pS100, being negative for CK20, and MUC-2. PET-scan revealed no systemic disease and confirming no metastatic origin. Conclusions The SN-ITACs are a very uncommon neoplasm, localized mainly in the ethmoidal sinus, nasal cavity and maxillary sinus. The SN-ITACs are very likely to the intestinal adenomas and adenocarcinomas, these tumors could be positive to CK20, MUC-2, and CDX-2. The differential diagnosis is the pleomorphic adenoma and its malignant counterpart (Carcinoma ex-pleomorphic adenoma), metastatic adenocarcinomas must be included in the differential diagnosis especially those with gastro-intestinal origin. Renal, breast and prostate carcinomas has been reported with sinonasal metastasis.