Rare Prostate Tumor: A Benign PEComa Case
"A closer look at perivascular epithelioid cell tumors (PEComas) and a unique case of a benign prostatic PEComa, offering insights for diagnosis and treatment."
Perivascular epithelioid cell tumors, or PEComas, are a rare type of mesenchymal tumor. These tumors can develop in various locations throughout the body. What makes PEComas unique is the presence of perivascular epithelioid cells. These cells share characteristics of both muscle and melanocytes (pigment-producing cells), expressing markers associated with both.
PEComas are often benign, some can become aggressive, exhibiting characteristics like rapid growth or the ability to spread to other parts of the body (metastasis). When possible, surgical removal is the preferred treatment. In situations where surgery isn't an option, radiation therapy, chemotherapy, and immunotherapy have been explored, either alone or in combination.
When it comes to the prostate, PEComas are extremely rare. This article explores the first reported case of a benign prostatic PEComa, successfully treated with transurethral resection. This case offers valuable insights into the diagnosis and management of this unusual tumor.
Diagnosis and Treatment of Prostatic PEComa
PEComas are mesenchymal tumors that can arise in many parts of the body, although kidneys and lungs are among the most common sites of PEComa-spectrum disease. Prostatic PEComa is extremely rare, and the available literature has reported radiation therapy, cytotoxic chemotherapy, and immunotherapy as treatment options, alone or in combination. The reported benign prostatic case was treated with transurethral resection. Diagnosis relies on recognizing perivascular epithelioid cells with myomelanocytic immunophenotype and negative epithelial-marker staining.
Defining PEComa as a Distinct Tumor Family
PEComas are characterized as uncommon mesenchymal neoplasms composed of perivascular epithelioid cells with dual myomelanocytic differentiation. Because they lack a site-specific cell of origin, they can develop in a wide variety of anatomic locations. The reported literature describes PEComa as a rare family of tumors whose clinical features, histopathology, and current therapy have been the subject of continuing review. Most cases are associated with sporadic mutations involving TSC1, TSC2, or TFE3 genes, although the cited review notes that a subset has other features.
Decoding PEComas: What Makes Them Unique?
The World Health Organization defines PEComas based on their distinct histological and immunohistochemical features. These tumors are primarily composed of epithelioid cells that stain positive for HMB-45, a melanocytic marker. These cells typically have clear or granular cytoplasm and a centrally located nucleus.
- Clear Cell Sarcoma: Vascular stroma and perivascular arrangement is not common in clear cell sarcoma, and nearly all are positive for $100 protein.
- The prostatic tumor showed low mitotic activity, coagulative necrosis and malignant behavior.
- PEComa, shows strong and diffuse staining for only HMB-45 in the spindle and epithelioid cell components.
A Broad Anatomic and Clinical Spectrum
Recent reviews describe PEComa as a rare family of mesenchymal tumors that includes angiomyolipoma, lymphangioleiomyomatosis, pulmonary clear cell “sugar” tumors, and PEComa-not otherwise specified. Reported sites include the retroperitoneum, abdominopelvic region, uterus, uterine cervix, vagina, gastrointestinal tract, kidney, liver, bladder, prostate, soft tissue, skin, and bone. The 2025 Japanese Journal of Clinical Oncology review aimed to summarize the clinical features, molecular biology, and current treatment of PEComa.
Unpredictable Biological Behavior
Prostatic PEComas are described as having unpredictable biological behavior. They are mostly benign, but some tumors can become unresectable or metastatic. This creates a limitation for relying on the usual benign presentation when assessing prognosis. The cited Targeted Oncology source addresses ongoing advances in immunotherapy, biomarkers, cancer pathways, and targeted precision medicine for malignant PEComa.
Benign Prostatic PEComa in Context
The reported case literature identifies benign prostatic PEComa as an unusual clinical outcome within a tumor family that can also display aggressive behavior. The cited report describes the first case of benign prostatic PEComa with long-term follow-up and states that it was the second reported case of PEComa of the prostate. It also notes that new targeted therapies may emerge for localized aggressive and metastatic PEComa. This contrast illustrates why localized benign disease and advanced disease require different considerations.
The Future of PEComa Treatment: A Call for More Research
This report highlights the first documented instance of a benign prostatic PEComa, accompanied by extended follow-up. While most PEComa lesions tend to be benign, certain tumors exhibit malignant characteristics and aggressive clinical progression, including the potential for distant metastasis.
Toward Risk-Based Prognosis
The PEC-PRO study retrospectively examined patients with localized PEComa-NOS across French Sarcoma Network centers. Cases were reviewed by a local sarcoma expert pathologist using morphologic criteria and immunohistochemical profiles consistent with the WHO Classification of Soft Tissue Sarcomas. The investigators analyzed 12 clinicopathologic features in a Cox proportional hazard framework to derive a multivariate model for event-free survival. A related report describes PEC-PRO as a prognostic score based on 87 patients and four key variables: tumor size, mitotic rate, necrosis, and patient sex.
Molecular Diagnostics and Targeted Therapy
A 2026 market forecast projects growth in the PEComa market from 2026 to 2036, associating that outlook with increased awareness, advances in molecular diagnostics, and targeted therapies for advanced and unresectable disease. The cited forecast identifies the Perivascular Epithelioid Cell Neoplasm market as the subject of its analysis. Another 2026 report, titled “PEComa Market Size, Epidemiology, In-Market Drugs Sales, Pipeline Therapies, and Regional Outlook 2026-2036,” describes PEComa as a rare mesenchymal neoplasm originating from perivascular epithelioid cells. Expert discussion also identifies future research areas in malignant PEComa and the evolution of its treatment landscape.
Limited Evidence in Advanced Disease
Surgical resection is described as the mainstay of PEComa therapy. However, approximately one third of patients in the cited 2014 source either have advanced disease at presentation or later develop metastases. The role of chemotherapy remains controversial, with only anecdotal responses reported, including some responses involving mTOR-directed treatment. A 2023 study likewise states that evidence for treating advanced PEComa is scarce and that only one FDA-approved treatment was available at the time of that report.
Challenges Across Care Settings
Prostatic PEComa is described as extremely rare, with only one malignant case reported in the cited case source. The rarity of the tumor can create diagnostic and treatment challenges across oncology settings. A 2026 care-delivery white paper examines PEComa management across academic and community oncology, using real-world perspectives from both settings to discuss diagnosis, treatment, and long-term management. It emphasizes that care requires precision, speed, and an integrated approach across the cancer-care system.
Currently, there is no established effective medical treatment for individuals with advanced PEComa. To accurately forecast the biological behavior of PEComas and determine the most effective treatment strategies, further research involving additional cases and longer follow-up periods is essential.
As our understanding of PEComas deepens, new targeted therapies may emerge as definitive treatments for localized aggressive and metastatic cases, offering hope for improved outcomes. This case contributes valuable data to the growing body of knowledge surrounding PEComas.