Perivascular epitheloid cell tumour (PEComa) of the retroperitoneum - a rare tumor with uncertain malignant behaviour: a case report

Multifocal retroperitoneal and pelvic PEComas mimicking liposarcoma: A case report and review of literature

Perivascular epithelioid cell neoplasms (PEComa) constitute a rare, but increasingly recognized family of seemingly distinct mesenchymal tumors which can occur in any part of the body. Due to their rarity, radiological descriptions of PEComas in the current literature are few and non-specific, making diagnosis difficult, though some common imaging features have been reported. We present an unusual case of multifocal retroperitoneal and pelvic PEComas, mimicking liposarcoma, subsequently treated with open surgery.

Chylous Ascites as a Presentation of Lymphangioleiomyomatosis

A 35-year-old woman presented to the hospital with a 4-week history of large-volume chylous ascites refractory to paracentesis and new-onset dyspnea. Thoracic computed tomography revealed diffuse pulmonary cystic lesions with pleural effusions, and abdominal computed tomography showed ascites with large bilateral retroperitoneal masses displaying positron emission tomography avidity. Biopsy of the masses demonstrated lymphatic invasion by a perivascular epithelioid cell neoplasm, a smooth muscle tumor. The patient was diagnosed as having the sporadic form of lymphangioleiomyomatosis and was treated with the mammalian target of rapamycin pathway inhibitor sirolumus with clinical improvement.

Retroperitoneal perivascular epithelioid cell tumours: A case report and review of literature

BACKGROUND

The perivascular epithelioid cell tumour (PEComa) family of tumours mainly includes renal and hepatic angiomyolipomas, pulmonary lymphangioleiomyomatosis and clear cell “sugar” tumour of the lung. Several uncommon tumours with similar morphological and immunophenotypical characteristics arising at a variety of sites (abdominal cavity, digestive tract, retroperitoneum, skin, soft tissue and bones) are also included in the PEComa family and are referred to as PEComas not otherwise specified.

CASE SUMMARY

We present a 37-year-old female patient who underwent resection of an 8.5 cm × 8 cm × 4 cm retroperitoneal tumour, which eventually was diagnosed as PEComa of uncertain biological behaviour. Three years after the operation, the patient remains without any evidence of recurrence. A search was performed in the Medline and EMBASE databases for articles published between 1996 and 2018, and we identified 31 articles related to retroperitoneal and perinephric PEComas. We focused on sex, age, maximum dimension, histological and immunohistochemical characteristics of the tumour, follow-up and long-term outcome. Thirty-four retroperitoneal (including the present one) and ten perinephric PEComas were identified, carrying a malignant potential rate of 44% and 60%, respectively. Nearly half of the potentially malignant PEComas presented with or developed metastases during the course of the disease.

CONCLUSION

Retroperitoneal PEComas are not as indolent as they are supposed to be. Radical surgical resection constitutes the treatment of choice for localized disease, while mammalian target of the rapamycin (mTOR) inhibitors constitute the most promising therapy for disseminated disease. The role of mTOR inhibitors as adjuvant or neoadjuvant therapies needs to be evaluated in the future.

Recurrence of retroperitoneal localized perivascular epithelioid cell tumor two years after initial diagnosis: case report

CONTEXT

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors. Adjuvant radiotherapy and/or chemotherapy are administered according to the patient's clinical characteristics.

CASE REPORT

A 42-year-old female patient was operated to treat a retroperitoneal mass. The diagnosis was established as PEComa with benign behavior. Two years after the diagnosis, chest and abdominal computed tomography scans showed intra-abdominal recurrence and lymphangioleiomyomatosis in the lung. Treatment with everolimus was started. The disease stabilized in the third month of treatment, according to the response evaluation criteria in solid tumors.

CONCLUSION

PEComas are tumors with unpredictable behavior. Therefore, these patients require long-term follow-up, even in cases of correct diagnosis and benign PEComa.

[A case of malignant perivascular epithelioid cell tumor of the retroperitoneum with multiple metastases]

Perivascular epithelioid cell tumors (PEComas) are unusual mesenchymal neoplasms composed of histologically and immunohistochemically distinct perivascular epithelioid cells (PECs). Although PEComas have the potential to behave in a malignant fashion, malignant PEComas arising from the retroperitoneum are extremely rare. A 68-year-old woman presented with a painful palpable mass in her left upper abdomen. Computed tomography of the abdomen showed a 9 cm sized heterogeneous mass in left para-aortic space and multiple hypervascular nodules in the liver. (18)F-fludeoxyglucose-PET/CT showed multifocal hyper-metabolic lesions in retroperitoneum, liver, and skeletal bones. Percutaneous needle biopsies were done on the retroperitoneal and hepatic mass. Both specimens were positive for human melanoma black-45 (HMB-45) on histological and immunohistochemical staining which was compatible with PEComas. Herein, we report a rare case of retroperitoneal PEComa with multiple metastases involving liver and bone at initial diagnosis that exhibited aggressive behavior and resulted in a devastating prognosis.

PEComa: morphology and genetics of a complex tumor family

Perivascular epithelioid cell tumors, or PEComas, are mesenchymal neoplasms composed of histologically and immunohistochemically distinctive epithelioid or spindle cells, which are immunoreactive for both smooth muscle and melanocytic markers. The cells in PEComas are typically arranged around blood vessels and appear to form the vessel wall, often infiltrating the smooth muscle of small- to medium-sized vessels. Periluminal cells are usually epithelioid and the more peripheral cells are spindle shaped. The cells have small, round to oval nuclei, sometimes with focal nuclear atypia, and clear to eosinophilic cytoplasm, and no counterpart normal cell has been identified. The PEComa "family" now includes angiomyolipoma, pulmonary clear cell "sugar" tumor and lymphangioleiomyomatosis, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, abdominopelvic sarcoma of perivascular epithelioid cells, and other tumors with similar features at various sites that are simply termed PEComa. Some PEComas occur in patients with tuberous sclerosis complex and share the genetic abnormalities. There is a behavioral spectrum from benign to frankly malignant, and histologic criteria have been proposed for assessing malignant potential. The differential diagnosis can include carcinomas, smooth muscle tumors, other clear cell neoplasms, and adipocytic tumors. PEComas constitute a genetically diverse group that includes neoplasms harboring TFE3 gene rearrangements and those with TSC2 mutations, indicating alternative tumorigenic pathways. Recent advances in therapy of malignant PEComas relate to increased knowledge of specific genetic changes and their effects on metabolic pathways that are susceptible to specific interventions. We review PEComas, emphasizing the diagnostic spectrum and recent immunohistochemical and genetic findings.

Malignant perivascular epithelioid cell tumor of the retroperitoneum

Perivascular epithelioid cell tumors (PEComas) are a rare type of mesenchymal neoplasms characterized by a proliferation of perivascular cells with an epithelioid phenotype and expression of myo-melanocytic markers. The majority of PEComas seem to be benign and usually their prognosis is good. Malignant cases are extremely rare, exhibiting a malignant course with local recurrences and distant metastases. We herein report a case of a malignant PEComa arising in the retroperitoneum. The patient was a 55-year-old woman experiencing abdominal discomfort for approximately one month. Ultrasound and computer tomography (CT) scans of the abdomen revealed a solid mass arising from the retroperitoneum. Microscopically, the tumor was composed of epithelioid cells mixed with spindled cells. The nucleus had significant atypia, and the mitoses were obvious. The focal intravascular tumor embolus was visible. Immunohistochemically, the epithelioid tumor cells were positive for HMB45 and Melan-A, and the spindled tumor celLs were positive for SMA and desmin. Seven months after a surgical resection, an ultrasound revealed liver metastases. In conclusion, the malignant PEComas of the retroperitoneum is a very rare neoplasm with unique morphological and immunohistochemical characteristics. It should be differentiated from other epithelioid cell tumors of the retroperitoneum.

Perivascular epithelioid cell tumor located retroperitoneally with pulmonary lymphangioleiomyomatosis: report of a case

Perivascular epithelioid cell neoplasms, also known as "PEComas", are unusual mesenchymal tumors, exhibiting perivascular epithelioid cell differentiation and characterized by a mixed myogenic and melanocytic phenotype. "PEComas not otherwise specified" (PEComas-NOS) are especially rare; consequently, there are no published large series, but only case reports. These tumors are rarely located retroperitoneally, with only about 15 such cases reported. We report a case of pulmonary diffuse lymphangioleiomyomatosis with large retroperitoneal PEComa-NOS in a 66-year-old woman. Treatment consisted only of tumor resection, without additional adjuvant therapy. We emphasize the importance of correct immunohistochemistry diagnosis, initiation of recommended treatment, and surveillance of this unique family of tumors.

Bladder perivascular epithelioid cell tumor: a novel rare neoplasm

Perivascular epithelioid cell tumors (PEComas) have recently been defined as a group of neoplasms that have in common the co-expression of melanocytic and smooth muscle markers. We report a novel case of a rare bladder PEComa and we review the relevant literature.