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SEER Inquiry System - Report
Produced: 10/30/2025 10:45 PM
Question 20130152
Inquiry Details
References:
ICD-O-3
Question:
Primary site/Histology--Brain and CNS: How is the primary site and histology coded for a 2013 diagnosis of squamous cell carcinoma arising in a dermoid cyst of the third ventricle? See Discussion.
Discussion:
Patient has a dermoid cyst of the third ventricle of the brain diagnosed in 1998. In 2013 the cyst was removed and was diagnosed as squamous cell carcinoma. An internet search revealed a journal article in the Journal or Neuro-Oncology that states, "Although rare, malignant transformation of intracranial epithelial cysts has a poor prognosis." The combination of site C715 [third ventricle, NOS] and histology 8070/3 [squamous cell carcinoma] fails SEER Edit IF 38_3: Primary site and Morphology Impossible.
Answer:
According to the literature, intracranial squamous cell carcinoma is very rare with most cases arising from a preexisting benign epidermoid cyst. The combination of C71_ and 8070/3 should be allowed. We will submit a request to have this edit revised.
Cancer Site Category:
Brain and CNS
Data Item Category:
Primary site, Histology
Other Category:
N/A
Year:
2013
