Sinonasal Adenocarcinoma with Neuroendocrine Differentiation: Case Report and Review of Literature

Background: Sinonasal mixed adenocarcinoma with neuroendocrine features is a rare tumor with no treatment guidelines. These tumors can be very aggressive, with locoregional and distant spread. Adenocarcinomas are generally non-responsive to chemotherapy unless an intestinal-type with a retained functional p53 protein. Neuroendocrine differentiation might be another indication to include chemotherapy in the management of these tumors.

Case Presentation: 64-year-old Jehovah's witness wood-worker presented with right sided epistaxis and right facial swelling. Imaging showed a sinonasal mass with an epicenter in the right olfactory cleft and the biopsy was consistent with high grade sinonasal adenocarcinoma with neuroendocrine differentiation. A PET/CT scan did not show any loco-regional or distant metastasis and he was staged as cT4aN0M0. Immunohistochemical studies were positive for CK7, chromogranin, synaptophysin and CDX-2. EGFR, TP53 and CK20 were all negative. He underwent endoscopic endonasal anterior skull base resection with negative margins and completed adjuvant intensity modulated radiation therapy. One year later, he presented with a right cervical mass and the fine needle aspiration confirmed the presence of neuroendocrine cells consistent with metastasis. He underwent definitive chemotherapy. One year later the patient presented with hilar metastasis.

Discussion: Mixed adenoneuroendocrine carcinoma (MANEC) have been poorly described, with only 5 cases published in the English literature. MANECs are mostly found in males with a mean age of 60.6 years and these tumors are considered aggressive neoplasms associated with poor prognosis. An important prognostic factor remains the differentiation grade. Management and sequence of therapy is not well described but some reports suggest induction chemotherapy followed by either surgery with chemoradiation or definitive chemoradiation. Other reports show that chemotherapy does not improve overall survival in neuroendocrine carcinomas and the main treatment consists of surgery followed by radiation therapy.

Conclusion: Neuroendocrine differentiation in sinonasal adenocarcinomas should be properly detected by experienced pathologists and quantified as the percentage of the tumor. No optimal treatment strategy has been described. Despite not improving overall survival, chemotherapy could be considered to aid in prevention of locoregional and distant spread and as a biomarker to determine the sequence of therapy when a neoadjuvant treatment strategy.

Fig. 1 MRI T1 with contrast showing a large enhancing mass centered within the right nasal cavity abutting the orbit and the anterior base of skull.

Fig. 2 40× close-up synaptophysin immunoperoxidase stain population of synaptophysin (+) cells (brown).

Fig. 3 40× close-up H&E, area with glandular lumina.

 

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No conflict of interest has been declared by the author(s).