An official website of the United States government
Home
SEER Inquiry System - Report
Produced: 04/26/2026 1:05 AM
Question 20160070
Inquiry Details
References:
WHO Class H & N Tumors, 19. 2005
Question:
Primary site/MP/H Rules/Histology: What is the appropriate site and histology code for a tumor described as a "Large mass In suprasellar cistern encroaching into sphenoid & ethmoid sinuses", with the pathology described as "INI-1 deficient sinonasal undifferentiated carcinoma"? Of note, this patient has a history of a pituitary adenoma, resected overseas a few months prior to this diagnosis.
Discussion:
Answer:
The primary site is unclear. The lesion is intracranial, but this may not be the primary site. In the absence of any additional information, assign C390, 8020/3. According to WHO, sinonasal undifferentiated carcinoma can involve the nasal cavity, maxillary antrum, and/or ethmoid sinus.
SMARCB1 (INI-1) is a tumor-suppressor gene located on chromosome 22q11.2. Tumors that showed loss of expression were SMARCB1-deficient tumors which are characterized by nests, sheets, and cords of cells without any histologic evidence of specific (eg, squamous or glandular) differentiation.
