The final pathology of the mass was SNUC, the patients second skull base lesion and third primary neoplasm.
SNUC is composed of small to medium-sized cells arranged in nests, sheets, and trabeculae, conferring a neuroendocrine appearance.
The differential diagnosis for SNUC spans lymphoma, esthesioneuroblastoma, melanoma, squamous cell carcinoma, rhabdomyosarcoma, and nasopharyngeal-type undifferentiated carcinoma.
SNUC can be distinguished from esthesioneuroblastomas by the histologic occurrence of intercellular fibrils and periodic Homer Wright rosettes in esthesioneuroblastomas.
The differential diagnosis of SNUC primarily includes poorly differentiated squamous cell carcinoma, high-grade/poorly differentiated adenocarcinoma, olfactory neuroblastoma (high-grade), small cell undifferentiated neuroendocrine carcinoma (NEC), mucosal malignant melanoma, nasal-type natural killer (NK)/T-cell lymphoma, and rhabdomyosarcoma.
The suggestion has been made that even in the presence of differentiated foci (eg, squamous cell differentiation), albeit focally, the diagnosis of SNUC can be rendered in the appropriate clinical setting unique to this neoplasm.
19,20) However, unequivocal confirmation supporting the concept that ONB, SNUC, or NEC belong to the primitive neuroectodermal tumor family has not been identified, and many studies have contradicted the notion that ONB represents a PNET.
Histopathologically, SNUC shares some similarities with nasopharyngeal carcinoma and squamous cell carcinoma.
8) SNUC is a distinct and aggressive entity that should be diagnosed early and treated aggressively.
To our knowledge, we describe the first reported association of an SCC and OSP and the third report of an SNUC arising in OSE Sinonasal undifferentiated carcinoma is a recently described highly aggressive neoplasm of the sinonasal tract.
Both tumors showed an intimate relationship of the OSP to either SCC (case 1) or SNUC (case 2).
In conclusion, we report 2 additional cases of malignancies arising in OSPs, including the first case of a synchronous SCC and the third case of a synchronous SNUC.