Case 115
- Wangpan Shi
- May 18
- 1 min read
A 76-year-old female with a large subcutaneous thigh mass.

The tumor is sent for NGS testing and KMT2D p.R2099* with VAF of 42% and CCND1 amplification. What's your diagnosis?
A: malignant triton tumor
B: rhabdomyosarcoma
C: spindle cell melanoma
D: fibrosarcoma
Answer
The tumor is positive for both SOX10 and S100. H3K27 trimethylation (H3K27me3) stain retained and negative for BRAF. CCND1 amplification are associated with mucosal melanoma.
Case credit: UCSD Pathology
Author: Wangpan Jackson Shi, MD
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