Necrotic Spindle Cell Neoplasm
Rob Bookstein, MD (Fellow), Mark Ewalt, MD (Molecular Pathology Attending), Wonwoo Shon, DO (Surgical Pathology Attending)
A 70 year old man with a history of multiple back surgeries for spinal stenosis was found to have a right lower quadrant mass during follow-up CT scan. The outside imaging is not available, but reportedly showed a 9 x 8 x 7 cm circumscribed mass with features of a proteinaceous cyst, unrelated to appendix with no invasion of contiguous small bowel or colon. A CT-guided needle biopsy showed necrotic spindle cell tumor, and the patient underwent laparotomy for excision of the mass.
|Study / Test (Clone)||Result|
|DOG-1 (K9)||Positive (tumor cells)|
|Pancytokeratin (AE1/AE3)||Negative (tumor cells)|
|Actin, smooth muscle (Alpha am-1)||Negative (tumor cells)|
|Desmin (DE-R-11)||Negative (tumor cells)|
|S100 Polyclonal||Negative (tumor cells)|
|CD117 [C-Kit] QL||Positive (tumor cells)|
|ETS Transcription Regulator (EPR3864)||Negative (tumor cells)|
|ALK-1 Protein (5A4)||Negative (tumor cells)|
KIT gene sequencing (Mayo Laboratories) - test not performed due to lack of viable tumor
CS-Focus GIST Panel by NGS (Cedars-Sinai PLM) - following macrodissection of small viable tumor area
- Predominantly necrotic spindle cell neoplasm, consistent with subtotally necrotic gastrointestinal stromal tumor (GIST).
- 7.3 x 6.3 x 5.8 cm
- >5 mitoses per high power field
- Tumor present at specimen surface
- KIT V559A variant (allele fraction 14.8%) detected by CS-Focus GIST Panel
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