What is PEComa?

Perivascular epithelioid cell tumors (PEComas) are ultra-rare carcinomas, representing a family of mesenchymal tumors arising from perivascular epithelioid cells (PECs) that surround the blood vessels. PEComas can occur in any part of the body, with most commonly in the abdominal cavity, pelvic region (uterus in women), and the gastrointestinal tract.

The most common types of PEComas are angiomyolipoma (AML) and lymphangioleiomyomatosis (LAM), and clear cell sugar tumor (CCST). Less well-characterized PEComas of a variety of anatomic origins are called PEComa- not otherwise specified (PEComa-NOS).

What are the risk factors for PEComa?

A few risk factors for PEComa have been noted, including having tuberous sclerosis complex (TSC), which is a genetic disorder characterized by the growth of numerous benign tumors in many parts of the body. TSC is caused by mutation of the TSC1 or TSC2 genes. Both these genes suppress tumor growth in the body by regulating cell growth through inhibition of a protein called mammalian target of rapamycin, or mTOR for short. When either the TSC1 or TSC2 gene is mutated (defective), the mTOR biological pathway is over activated and cell growth becomes abnormal.

While both males and females are affected, there is a strong female predominance of 6:1 ratio.

The onset of PEComas can range at any age (3-97 years), with the average age of diagnosis at 45 years.

Signs and Symptoms?

PEComa can have a myriad of features, its signs and symptoms depend on the size, location, and subtype of the tumor, and whether it is benign or malignant. Smaller tumors may not exhibit any symptoms, but larger tumors can affect the functioning of the organ that is involved. Malignant tumors that metastasized may show a variety of symptoms depending on the site of metastatic lesion.

How is PEComa diagnosed?

Upon suspected malignancy, radiologic imaging studies (including CTs, MRIs) can be used to identify affected regions, then a biopsy of the tumor is used to arrive to a definitive diagnosis.

How PEComa is treated?

Treatment depends on whether the PEComa is malignant or benign. Most PEComas are benign at diagnosis,and depending on their locations,maybe easily removed via surgery. However, there is a subset of aggressive PEComas, advanced malignant PEComas, that are either metastatic or locally advanced, for which surgery is not an option, and for which there are currently no approved therapies. Malignant tumors are currently treated with a blend of radiation therapy, chemotherapy, and surgery.

The prognosis for patients with malignant disease is poor, with a median survival of 12-17 months after diagnosis of advanced disease. Therefore, the treatment for advanced PEComas represent a significant clinical need to improve therapeutic outcomes. The mTOR pathway, which is inhibited by TSC1-TSC2 complex, is frequently deregulated in PEComas, making it a promising target for treatment.