A rare case of nasal Schneiderian (inverted) papilloma associated with basaloid squamous cell carcinoma.

Sinonasal inverted papilloma (IP) is a benign, locally aggressive epithelial neoplasm. In less than 9% of cases it is associated with malignancies, typically conventional squamous cell carcinomas (SCC), while other histological variants have been less frequently reported. We describe the third case of basaloid squamous cell carcinoma (BSCC) arising in nasal IP. An 81-year-old female patient presented with a pinkish irregular lesion on the nasal septum. Biopsy was consistent with IP and carcinoma in situ. Two surgical procedures were needed to obtain radical excision. Histology on the surgical specimen revealed BSCC. Seven months after surgery, there was no evidence of disease recurrence. Although IP is more frequently associated with conventional SCC, other malignancies should be considered. The histological differential diagnosis should be supported by immunohistochemistry. The generally-recommended treatment for sinonasal BSCC is complete surgical resection, although this may be a problem in multifocal distributions, as in the present case.