Presentation
Right eye pain and swelling for a month. Right-sided nasal obstruction and facial paresthesia.
Patient Data
Maxillofacial CT scan with intravenous contrast demonstrates an enhanced soft tissue mass in the right anterior ethmoid sinus and nasal cavity, breaking through the medial wall of the right orbit and extending into the extraconal space of the right orbit, with a mild mass effect on the adjacent medial rectus muscle.
MRI brain with and without contrast demonstrates a 3.2 x 2.8 x 2.3 cm, lobular, heterogeneously enhancing mass in the anterior right ethmoid sinus and nasal cavity. The mass exhibits intermediate T1 and T2 signals and marked diffusion restriction (ADC lower than that of the brain).
There is invasion through the right medial orbital wall into the extraconal space with lateral deviation of the medial rectus muscle and abutment of the superior oblique muscle. The mass also invades the right frontal sinus with secondary right frontal sinus mucosal thickening. The mass obstructs the right ostiomeatal complex, resulting in mucosal thickening in the right maxillary and posterior right ethmoid sinuses.
FDG PET/CT scan demonstrates abnormally increased metabolic activity in the right nasoethmoid mass with a SUVmax of 42.8. Since the study 2.5 weeks prior, the mass has enlarged and further invaded the right orbit.
Case Discussion
This patient had a right-sided sinonasal mass notable for bone erosion and orbital invasion on CT, marked restricted diffusion on MRI, and intense FDG avidity on PET scan. The findings suggested a highly aggressive and cellular sinonasal malignancy.
The radiological appearance is not specific to particular histopathology but suggests a small round blue cell tumor of the sinonasal tract 1. This differential includes high-grade carcinomas (sinonasal undifferentiated carcinoma, sinonasal neuroendocrine carcinoma, squamous cell carcinoma, NUT carcinoma), olfactory neuroblastoma (esthesioneuroblastoma), mucosal melanoma, hematolymphoid tumors (lymphoma, plasmacytoma), and sarcomas (Ewing sarcoma/primitive neuroectodermal tumor, rhabdomyosarcoma, mesenchymal chondrosarcoma, small cell osteosarcoma).
An endoscopic biopsy was obtained, with frozen sections showing a small blue-cell tumor. Immunohistochemistry detected diffuse nuclear positivity for the NUT1 protein. The final pathologic diagnosis was NUT carcinoma. NUT carcinoma is a rare, aggressive malignancy that has a predilection for midline sites, is defined by translocations of the NUT (nuclear protein in testis) gene, and carries a poor prognosis.
Co-author: Dr. Francis Deng
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