Sinonasal Neoplasms Involving the Cranial Base and Orbit: A Case Series of Unusual Pathology and Review of the Literature

Objective: The differential diagnosis for neoplasms involving the nasal cavity and paranasal sinuses is quite broad, and patients often present with non-specific symptomatology. Imaging may demonstrate involvement of the cranial base and orbit, but there are not always distinct radiologic characteristics to pinpoint a diagnosis. While squamous cell carcinomas and other epithelial neoplasms represent the majority of malignant sinonasal neoplasms, we review a series of patients with poorly differentiated malignancies that illustrate some of the diagnostic and therapeutic challenges in this wide spectrum of diseases.

Design: Retrospective case series.

Setting: Academic Tertiary Care Center.

Methods: All patients who presented with sinonasal masses involving the cranial base and orbit in 2015 in our institution were reviewed. We analyzed presenting symptoms, imaging characteristics, initial and final histopathologic findings, including immunohistochemistry (IHC), and definitive management. A literature review was also performed to assess diagnostic characteristics and treatment options for these infrequently encountered neoplasms.

Results: A total of 50 cases were reviewed, and 10 patients were selected given their uncommon diagnoses and therapeutic challenges. These included malignant mucosal melanoma, sinonasal undifferentiated carcinoma (SNUC), plasmablastic lymphoma, and basaloid squamous cell carcinoma. Their histopathologic appearance, IHC profile, and unique diagnostic characteristics are presented and reviewed. Treatment modalities consisted of surgery, radiation, chemotherapy, or a combination thereof. The literature review encompasses previous reports with a focus on histopathology and IHC in establishing a diagnosis. Treatment options are also reviewed for these rare neoplasms.

Conclusion: The anterior and middle cranial base may be directly involved by a variety of sinonasal processes. It is important to review imaging characteristics and obtain a histopathologic diagnosis before proceeding further. Immunohistochemistry plays an important role in differentiating between many poorly differentiated or undifferentiated carcinomas. While the aforementioned sinonasal neoplasms are rarely encountered, establishing the diagnosis is important when considering management, counseling, and patient outcomes.