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Table of Contents
Definition / general | Essential features | Terminology | Sites | Pathophysiology | Clinical features | Case reports | Treatment | Clinical images | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Differential diagnosis | Board review question #1 | Board review answer #1Cite this page: Perivascular epithelioid cell tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorPEComa.html. Accessed July 14th, 2017.
Definition / general
- Mesenchymal neoplasm with melanocytic and smooth muscle features
Essential features
- Rare in gastrointestinal tract
- Positive for both HMB45 and smooth muscle actin
- See soft tissue article for more information
Terminology
- Also called PEComa
Sites
- Colon is the most common gastrointestinal site for PEComas (Medicine (Baltimore) 2016;95:e3890)
Pathophysiology
- Cyclin D1 possibly involved in tumorigenesis (Pathol Int 2006;56:46)
Clinical features
- Symptoms include abdominal pain, obstruction, and anemia
- Wide age range (median 45 years), slight female predilection (Am J Surg Pathol 2013;37:1769)
- May arise in children (Pediatr Dev Pathol 2014;17:406)
Case reports
- 7 year old Korean boy with ascending mass (Korean J Pediatr 2010;53:975)
- 16 year old girl with transverse mass (Tumori 2007;93:106)
- 17 year old girl with sigmoid mass (World J Gastrointest Oncol 2010;2:205)
Treatment
- Resection; mTOR inhibitors for metastatic disease (J Clin Oncol 2010;28:835)
Clinical images
Images hosted on other servers:
CT scan showing a cecal PEComa
Gross images
Images hosted on other servers:
Large cecal mass
Microscopic (histologic) description
- Tumor can exist anywhere within the wall; most commonly involves serosa/subserosa
- Sheets/nests of epithelioid cells with clear or eosinophilic cytoplasm
- Some tumors may show partially or predominantly spindled cells
- Tumor necrosis, vascular invasion, and occasional mitoses often present
- Metastatic lesions show more severe atypia and mitotic rates
Microscopic (histologic) images
Images hosted on other servers:
Low power
High power
HMB45 staining
Positive stains
- HMB45, MelanA, smooth muscle actin, desmin, rarely TFE3
Negative stains
- S100, cytokeratin, c-kit all rarely positive
Differential diagnosis
Board review question #1
A 15 year old girl develops anemia and abdominal pain. Workup identifies a 7 cm cecal mass that is resected. On H&E examination, the pathologist suspects the lesion may be a perivascular epithelioid cell tumor. What immunohistochemical markers would be positive in this lesion, to confirm the diagnosis?
A. Neural and melanocytic markers
B. Neural and skeletal muscle markers
C. Neural and smooth muscle markers
D. Skeletal muscle and melanocytic markers
E. Smooth muscle and melanocytic markers
A. Neural and melanocytic markers
B. Neural and skeletal muscle markers
C. Neural and smooth muscle markers
D. Skeletal muscle and melanocytic markers
E. Smooth muscle and melanocytic markers
Board review answer #1
E. Smooth muscle and melanocytic markers
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