| PEComa | |
|---|---|
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| Histopathologic image ofrenalangiomyolipoma.Nephrectomy specimen.H&E stain. | |
| Specialty | Oncology  |
Perivascular epithelioid cell tumour, also known asPEComa orPEC tumour, is a family ofmesenchymal tumours consisting ofperivascular epithelioidcells (PECs).[1] These are rare tumours that can occur in any part of the human body.
The cell type from which these tumours originate remains unknown. Normally, no perivascular epitheloid cells exist; the name refers to the characteristics of the tumour when examined under the microscope.[2]
Establishing the malignant potential of these tumours remains challenging although criteria[3] have been suggested; some PEComas display malignant features whereas others can cautiously be labeled as having 'uncertain malignant potential'.[2] The most common tumours in the PEComa family arerenalangiomyolipoma andpulmonarylymphangioleiomyomatosis, both of which are more common in patients withtuberous sclerosis complex. The genes responsible for this multi-system genetic disease have also been implicated in other PEComas.[2]
Many PEComa types shows a female predominance in the sex ratio.
The precursor cell of PEComas is currently unknown; there is no normal counterpart "perivascular epitheloid cell".[1] Genetically, PECs are linked to thetuberous sclerosisgenesTSC1 andTSC2, although this link is stronger for angiomyolipoma and lymphangioleiomyomatosis than for other members of the PEComa family.[4]
PECs consist of perivascularepithelioid cells with a clear/granularcytoplasm and central round nucleus without prominentnucleoli.
PECs typically stain for melanocytic markers (HMB-45,[5]Melan A (Mart 1),Mitf) and myogenic markers (actin,myosin,calponin).
PECs bear significanthistologic andimmunohistochemical similarity to:
Thus, it has been advocated that the above could be classified PEComas.[1]
PEComas are rare and can have myriad features; therefore, they can be confused withcarcinomas,smooth muscle tumours,adipocytic tumours, clear cellsarcomas,melanomas andgastrointestinal stromal tumours (GIST).[2]