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SEER Inquiry System - Report
Produced: 06/16/2026 10:30 AM
Question 20260010
Inquiry Details
References:
#1: ICD-O-3.2. Histology3_v26_20250903 NAACCR file
#2: Emerging Family of Spindle Cell… | College of American Pathologists. accessed 2/23/2026
Question:
Reportability/Histology--Breast: Is a spindle cell neoplasm with CLCN6::BRAF fusion reportable? If yes, how is the histology coded? See Discussion.
Discussion:
A right breast lumpectomy identified a spindle cell neoplasm with CLCN6::BRAF fusion. The diagnosis comment states, "There is limited data on spindle cell neoplasms with this specific fusion, therefore the outcome/malignant potential is unclear. The lesion is well circumscribed with low grade morphology but shows increased cellularity and mitotic activity that reaches 40 mitoses per 10 high power fields, which may be better considered as sarcoma for therapy purposes.” The physician clinically calls it a spindle cell sarcoma. Is this a reportable emerging sarcoma histology?
Answer:
Report this case of spindle cell neoplasm with CLCN6::BRAF fusion based on the physician diagnosis of spindle cell sarcoma (8801/3).
CLCN6::BRAF is described as rare kinase fusion identified in a subset of spindle cell sarcomas. It is part of an expanding group of BRAF fusions in spindle cell neoplasms though it not extensively detailed in the literature. Along with other BRAF fusions, CLCN6::BRAF represents a potential oncogenic driver for targeted therapy.
