Primary adenosquamous carcinoma of the maxillary sinus: A unique example showing diverse morphology and differentiation

Abstract

Adenosquamous carcinoma of the sinonasal tract is extremely rare. We report a case of such tumor in a 66-year-old Japanese male who presented with a 3.0-cm tumor in the maxillary sinus. The tumor mass filled the maxillary sinus, and part of the maxillary sinus floor was destroyed. Histological analysis showed that tumor cells with a marked atypia and pleomorphism with a high nuclear-cytoplasm ratio infiltrated beneath the mucosa. The tumor formed invasive nests and cribriform structures, and these structures were partially accompanied by marked necrosis. Additionally, tendency toward keratinization and peripheral palisading were present in the nests, and neoplastic cells showed varying cellular morphology including clear cells, where immunohistochemically positive staining for p63, p40 and CK5/6 was observed. While, immunoreactivity for these markers was absent in some of cribriform structures and solid nests, as well as areas showing fine nesting and cells surrounding glandular lumina. p16 was negative throughout the tumor, while p53 positive staining was detected throughout the tumor. CDX2 expression was observed in some solid nests. The tumor could be termed adenosquamous carcinoma, and also simultaneously considered to be essentially an adenocarcinoma derived from the ciliated epithelium of the maxillary sinus mucosa gradually increasing nuclear atypia with partial squamous metaplasia. The morphological transition was more clearly recognized in the p53 immunostaining. The patient died of disease two years after the primary surgery. This tumor is considered a histological type that can be fatal, and clinical attention is especially required when such a tumor encountered.

Keywords

• Adenosquamous carcinoma
• Sinonasal adenocarcinoma
• Non-intestinal type adenocarcinoma
• Ciliated epithelium
• Maxillary sinus
• Immunohistochemistry