Perivascular epithelioid cell tumors (PEComas)
Perivascular epithelioid cells tumors (PEComas) are a group of related mesenchymal tumors and tumor-like conditions found in many locations. This group includes:
- angiomyolipoma (AML)
- clear cell 'sugar' tumor of the lung
- lymphangioleiomyomatosis (LAM)
clear cell myomelanocytic tumor (CCMMT)
- of the falciform ligament / ligamentum teres
- unusual clear tumors of other organs
- abdominal serosa
- uterus - considered one of the commonest sites of involvement in the female pelvis
PEComas are far more common in females 4.
All PEComas share similar and distinctive cellular morphology – peripheral epitheloid cells – which have no counterpart in normal tissue 4. These tumors appear as sheets and nests of epithelioid or spindle-shaped cells associated with blood vessel walls. They have granular eosinophilic cytoplasms.
PEComas are characterized by immunoreactivity to smooth muscle and melanocytic markers 4.
- smooth muscle: actin, desmin
- melanocytic: HMB-45, melan-A
Unfortunately, due to non-specific imaging appearances and the scarcity of reported cases no specific imaging features are recognized. These lesions seem to usually be solid but can be centrally necrotic 5-7. They generally demonstrate prominent contrast enhancement 6.
Treatment and prognosis
PEComas usually behave in a benign fashion although local recurrence and even malignant behavior are encountered, mimicking malignant sarcomas.
Surgical excision is usually curative.
The differential diagnosis is broad and largely depends upon the location of the mass.
- 1. Lai HY, Chen CK, Lee YH et-al. Multicentric aggressive angiomyolipomas: a rare form of PEComas. AJR Am J Roentgenol. 2006;186 (3): 837-40. doi:10.2214/AJR.04.1639 - Pubmed citation
- 2. Fadare O, Parkash V, Yilmaz Y et-al. Perivascular epithelioid cell tumor (PEComa) of the uterine cervix associated with intraabdominal "PEComatosis": A clinicopathological study with comparative genomic hybridization analysis. World J Surg Oncol. 2007;2 (1): 35. doi:10.1186/1477-7819-2-35 - Free text at pubmed - Pubmed citation
- 3. Armah HB, Parwani AV. Malignant perivascular epithelioid cell tumor (PEComa) of the uterus with late renal and pulmonary metastases: a case report with review of the literature. Diagn Pathol. 2007;2 (1): 45. doi:10.1186/1746-1596-2-45 - Free text at pubmed - Pubmed citation
- 4. Hornick JL, Fletcher CD. PEComa: what do we know so far?. Histopathology. 48 (1): 75-82. doi:10.1111/j.1365-2559.2005.02316.x - Pubmed
- 5. Lubo, Idania, Fermín, Ileana, Massarelli, Olindo, Gobbi, Roberta, Cossu Rocca, Paolo. Perivascular Epithelioid Cell Tumour with Intraorbital Location: Report of a Case and Review of the Literature. (2018) Case Reports in Pathology. 2016: 1936421. doi:10.1155/2016/1936421 - Pubmed
- 6. Shen HQ, Chen DF, Sun XH, Li X, Xu J, Hu XB, Li MQ, Wu T, Zhang RY, Li KZ. MRI diagnosis of perivascular epithelioid cell tumor (PEComa) of the liver. (2013) Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie. 54 (3): 643-7. Pubmed
- 7. Md Shahid Alam, Bipasha Mukherjee, S Krishnakumar, Jyotirmay Biswas. Malignant perivascular epithelioid cell tumor of the orbit: Report of a case and review of literature. (2017) Indian Journal of Ophthalmology. 65 (9): 889. doi:10.4103/ijo.IJO_331_17 - Pubmed