Low grade sinonasal adenocarcinoma

Sinonasal adenocarcinoma is a rare neoplasm which is classified as'intestinal' or 'nonintestinal' type, depending on its resemblanceto gastrointestinal mucosa. These tumors are associated with occupational andenvironmental carcinogens. In this study, a fifty-year-old oil-painter malepatient with a low-grade nonintestinal type sinonasal adenocarcinoma originatingfrom the left middle concha and ethmoid sinus is presented. Microscopicalexamination revealed many infiltrative glandular structures, most of which werecystically dilated and some of which were smaller in diameter, arranged back toback in loose fibrous stroma as well as intraglandular papillary andmicropapillary structures forming complex branches or a cribriform pattern. Theglands were lined by epithelial cells that were faintly eosinophilic andrelatively abundant cubical/ cylinderical cytoplasms and mildly pleomorphicround/oval nuclei, with rare mitotic figures. Intraluminal and focallyintracytoplasmic mucin was demonstrated with Alcian Blue, mucicarmin and PASstains. Immunohistochemically, tumor cells were strongly and diffusely positivewith CK7; focally and weakly positive with CK20 and negative with CDX2 inaccordance with the nonintestinal type. S-100, Actin and p63, applied forinvestigating the myoepithelial and salivary glandular origins, were allnegative. Prognostic markers, TTF-1 and p53 were negative; while the Ki-67 indexwas 2%. The fact that intestinal type sinonasal adenocarcinomas are generallyhigh grade, while nonintestinal tumors are histologically low grade makes thismorphological and immunohistochemical-based classification valuable inpredicting the prognosis of the disease. In addition to the morphological andimmunohistochemical findings, clinical information stands out in thedifferentiation of the tumor from benign or malignant primary lesions ormetastatic adenocarcinoma.