Comprehensive Insights Into Renal Perivascular Epithelioid Cell Neoplasms: From Molecular Mechanisms to Clinical Practice.

Perivascular epithelioid cell neoplasms (PEComas) are a rare category of mesenchymal tissue tumors, manifesting across various tissues and organs such as the kidneys, liver, lungs, pancreas, uterus, ovaries, and gastrointestinal tract. They predominantly affect females more than males. PEComas characteristically express both melanocytic and smooth muscle markers, making immunohistochemistry vital for their diagnosis. Renal angiomyolipoma (AML) represents a common variant of PEComas, typically marked by favorable prognoses. Nonetheless, only a small fraction of subtypes, especially epithelioid AML, possess the capacity to be malignant. Renal PEComas usually appear as asymptomatic masses accompanied by vague imaging characteristics. The main methods for diagnosis are histopathological analysis and the application of immunohistochemical stains. Presently, a uniform treatment plan for renal PEComas is absent. Strategies for management include active surveillance, selective arterial embolization, surgical procedures, and drug-based treatments. The focus of this review is on renal PEComas, shedding light on their pathogenesis, pathological characteristics, clinical presentations, diagnosis, and treatment modalities, and incorporating a clinical case study.

PEC-PRO: A new prognostic score from a series of 87 patients with localized perivascular epithelioid cell neoplasms (PEComas) treated with curative intent.

BACKGROUND: Perivascular epithelioid cell neoplasms (PEComas) encompass a heterogeneous family of mesenchymal tumors. Previously described clinicopathologic features aimed at distinguishing benign from malignant variants but lacked prognostic value. METHODS: This retrospective analysis examined clinicopathologic data from patients who had localized PEComa across French Sarcoma Network centers. The authors analyzed 12 clinicopathologic features in a Cox proportional hazard framework to derive a multivariate prognostic risk model for event-free survival (EFS). They built the PEComa prognostic score (PEC-PRO), in which scores ranged from 0 to 5, based on the coefficients of the multivariate model. Three groups were identified: low risk (score = 0), intermediate risk (score = 1), and high risk (score ≥ 2). RESULTS: Analyzing 87 patients who had a median 46-month follow-up (interquartile range, 20-74 months), the median EFS was 96.5 months (95% confidence interval [CI], 47.1 months to not applicable), with 2-year and 5-year EFS rates of 64.7% and 58%, respectively. The median overall survival was unreached, with 2-year and 5-year overall survival rates of 82.3% and 69.3%, respectively. The simplified Folpe classification did not correlate with EFS. Multivariate analysis identified three factors affecting EFS: positive surgical margins (hazard ratio [HR], 5.17; 95% CI, 1.65-16.24; p = .008), necrosis (HR, 3.94; 95% CI, 1.16-13.43; p = .030), and male sex (HR, 3.13; 95% CI, 1.19-8.27; p = 0.023). Four variables were retained in the prognostic model. Patients with low-risk PEC-PRO scores had a 2-year EFS rate of 93.7% (95% CI, 83.8%-100.0%), those with intermediate-risk PEC-PRO scores had a 2-year EFS rate of 67.4% (95% CI, 53.9%-80.9%), and those with high-risk PEC-PRO scores had a 2-year EFS rate of 2.3% (95% CI, 0.0%-18.3%). CONCLUSIONS: The PEC-PRO score reliably predicts the risk of postoperative recurrence in patients with localized PEComa. It has the potential to improve follow-up strategies but requires validation in a prospective trial.

Cervical PEComa: Challenges in diagnosis and prognosis of a rare neoplasm.

•Cervical PEComas are rare neoplasms which present a diagnostic challenge.•Large tumour size is an important clinical prognosticator in cervical PEComa.•All reported cases of cervical PEComa classified as benign by Folpe criteria behaved in benign fashion clinically.•Tumours ≤ 4 cm may be assessed with cone biopsy, and simple hysterectomy considered if no adverse pathologic features.•Molecular characterization and linkage with coordinated rare tumour registries may identify novel treatments.

Primary Perivascular Epithelioid Cell Tumor of the Lung: A Case Report.

Perivascular epithelioid cell tumors (PEComas) are very rare mesenchymal neoplasms, composed of histologically and immunohistochemically distinctive cells that form a sheet-like appearance around vessel lumens. Although most are benign, a malignant subset does exist, complicating clinical diagnostic efforts. Proper evaluation and management are thus essential for long-term patient survival. Herein, we present a rare case of a benign pulmonary PEComa that was diagnosed postoperatively in a 45-year-old woman.

Perivascular epithelioid cell tumors of the liver misdiagnosed as hepatocellular carcinoma: Three case reports.

BACKGROUND: Hepatic perivascular epithelioid cell neoplasms (PEComas) are rare. Diagnostic and treatment experience with hepatic PEComa remains insufficient. CASE SUMMARY: Three hepatic PEComa cases are reported in this paper: One case of primary malignant hepatic PEComa, one case of benign hepatic PEComa, and one case of hepatic PEComa with an ovarian mature cystic teratoma. During preoperative imaging and pathological assessment of intraoperative frozen samples, patients were diagnosed with hepatocellular carcinoma (HCC), while postoperative pathology and immunohistochemistry subsequently revealed hepatic PEComa. Patients with hepatic PEComa which is misdiagnosed as HCC often require a wider surgical resection. It is easy to mistake them for distant metastases of hepatic PEComa and misdiagnosed as HCC, especially when it's combined with tumors in other organs. Three patients eventually underwent partial hepatectomy. After 1-4 years of follow-up, none of the patients experienced recurrence or metastases. CONCLUSION: A clear preoperative diagnosis of hepatic PEComa can reduce the scope of resection and prevent unnecessary injuries during surgery.

Malignant retroperitoneal PEComa: A case report with emphasis on radiological findings.

A perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm with distinctive perivascular epithelioid cells that usually demonstrates myomelanocytic differentiation. PEComas can arise in various organs and generally are benign. Uncommonly PEComas have been documented to be malignant with metastasis most frequently to the lung, liver, lymph nodes, and bone. Here, we present the case of a 59-year-old male with a malignant retroperitoneal PEComa with confirmed metastasis to the femur and suspected metastasis to the liver and lung. The purpose of this case study is to present the progression and findings of a metastatic malignant PEComa.

Malignant Pigmented Epithelioid Angiomyolipoma of the Kidney in a Child with Tuberous Sclerosis Complex.

INTRODUCTION: Pigmented epithelioid angiomyolipoma is a variant of epithelioid angiomyolipoma (EAML) that has not previously been described in children with tuberous sclerosis. CASE PRESENTATION: A 15-year-old boy with tuberous sclerosis had a rapidly enlarging renal mass associated with a left lung nodule. Microscopically it was a pigmented EAML, confirmed by immunohistochemistry. DISCUSSION/CONCLUSION: The pigmented variant of EAML can arise and metastasize from the kidney of a teenager with tuberous sclerosis.

Multi-slice spiral CT manifestations of perivascular epithelioid cell tumors / 中国基层医药

Objective:To investigate CT manifestations of perivascular epithelioid cell tumors.Methods:The multi-slice spiral CT manifestations in 11 patients with perivascular epithelioid cell tumors which were pathologically confirmed in the First Affiliated Hospital of Shantou University Medical College between October 2012 and August 2021 were retrospectively analyzed.Results:Perivascular epithelioid cell tumors were located in the kidney of eight patients, in the right lobe of the liver of two patients, and in the descending colon of one patient. The largest tumor, approximately 20.0 cm × 26.0 cm × 11.0 cm, was located in the kidney. The smallest tumor, 2.4 cm × 2.6 cm × 3.4 cm, was located in the colon. CT plain scans showed uniform density without bleeding, calcification, or fat in two patients, and non-uniform density with fatty change in two patients. Contrast-enhanced CT images showed non-uniform enhancement in the arterial phase in 10 patients and uniform enhancement in one patient. Contrast-enhanced CT images showed decreased degrees of enhancement of the lesions in 11 patients from the portal venous phase to the delayed phase and dilated and tortuous vascular shadows in 11 patients.Conclusion:The multi-slice spiral CT manifestations of perivascular epithelioid cell tumors are characteristic and the multi-slice spiral CT is of value for the diagnosis of perivascular epithelioid cell tumors.

A Rare Case of Epithelioid Hemangioma Presenting as an Isolated Sacral Mass.

Epithelioid hemangioma (EH) is an uncommon benign vascular tumor of mesenchymal origin. It mainly presents as expanding nodules around the ear, the forehead, and long bones. Only a handful of cases have been found in cervical, thoracic, lumbar, and sacral vertebrae as lytic lesions with pain and neurological impairment. We present the case of a 36-year-old female with an incidental finding of a sacral mass along with inguinal lymphadenopathy on imaging. Initially, there were no symptoms. The mass gradually progressed and later showed an extraosseous extension with involvement of sacral neural foramina and nerve roots causing severe low back pain and weakness of the left lower extremity. Differential diagnoses initially included secondary metastases and chordoma. However, the biopsy of the mass revealed findings consistent with an EH. To our knowledge, this is the first case of EH presenting as an isolated mass in the sacrum and the third case of EH involving the sacrum in continuation with other vertebrae. EH should be in our differential diagnoses when there is a sacral mass.

Advancements in the diagnosis and treatment of renal epithelioid angiomyolipoma: A narrative review.

Renal epithelioid angiomyolipoma (EAML) is a unique subtype of angiomyolipoma that contains a variety of cytoplasmic-rich, eosinophilic cytoplasm epithelioid cells in addition to mature adipocytes, hyaline thick-walled vessels, and smooth muscle-like spindle cells. In recent years, increasing evidence has shown that EAML is a potentially malignant tumor. Due to the lack of typical clinical manifestations and imaging features, it is difficult to diagnose before surgery, and the diagnosis mainly depends on postoperative histopathological examination. With the advancement of pathological diagnostic techniques, more EAML cases has been discovered, but clinicians still lack a comprehensive understanding of EAML. This review comprehensively describes some pathological and clinical features of EAML, with special attention to the pathogenesis and treatment of malignant EAML in order to assist with clinical diagnosis and treatment.

Single-center Experience in the Diagnosis and Treatment of Hepatic Perivascular Epithelioid Cell Neoplasm.

BACKGROUND AND AIMS: Perivascular epithelioid cell neoplasms (PEComas) are a rare type of mesenchymal neoplasm and their preoperative diagnosis is challenging. In this study, we summarized the experience from a single medical center to study the examinations, clinical presentations, and pathological and histological characteristics of PEComas in the liver in order to optimize overall understanding of the diagnosis and treatment of these neoplasms. METHODS: We conducted a retrospective analysis to investigate the clinical and pathological characteristics as well as imaging presentations of 75 patients diagnosed with hepatic PEComa in The First Affiliated Hospital of Zhejiang University between April 2010 and April 2020. RESULTS: Among the 75 patients, 52 were women, and the median age was 48 years. Most patients had no specific symptoms, and two were admitted to the hospital for a second time owing to relapse. All patients underwent surgical resection. Histologically, 38 patients had classical angiomyolipoma (AML) and 37 had epithelioid AML. The PEComas were accompanied by positive immunohistochemical expression of HMB45, Melan-A, and smooth muscle actin. Follow-up data were obtained from 47 of the total 75 patients, through October 2020. Two patients had metastasis after surgery. CONCLUSIONS: AML is the most common type of hepatic PEComa. There are no specific symptoms of hepatic PEComa, and serological examinations and imaging modalities for accurate preoperative diagnosis are lacking. Epithelioid AML should be considered a tumor of uncertain malignant potential; however, the prognosis of PEComa after resection is promising.

Clinical diagnosis and treatment of liver perivascular epithelioid cell neoplasms / 中华肝胆外科杂志

Objective:To analyze the clinical features and prognosis of liver perivascular epithelioid cell neoplasms (PEComa).Methods:The clinical data of 12 patients with liver PEComa diagnosed by pathology at the First Affiliated Hospital of Xi 'an Jiaotong University from October 2011 to November 2021 were retrospectively analyzed. There were 1 male and 11 females, with a median age of 44 (range 20 to 63) years old. The clinical manifestations, laboratory examinations, imaging features, treatment methods, postoperative pathological features and treatment outcomes of these patients were collected and analysed. Postoperative follow-up by telephone or patient's follow-up records.Results:Among the 12 patients with hepatic PEComa, 8 patients (66.7%) were asymptomatic and 11 patients (91.7%) had a single lesion. All patients underwent surgical treatment, including local tumor resection in 10 patients (83.3%) and extended hemihepatectomy in 2 patients (16.7%). Enhanced CT showed the lesion to be a quasi-round homogeneous low-density mass, enhanced in arterial phase with hepatic artery branches in the lesion, and decrease in enhancement degrees in portal vein phase and delayed phase. Postoperative pathology of the lesions in all the 12 patients was benign. Immunohistochemical results showed that the positive rates of melanoma cell markers HMB45, Melan-A and smooth muscle actin were 100.0%(12/12), 83.3%(10/12) and 91.7%(11/12) respectively. The median follow-up period was 27 months, and no recurrence or metastasis was found.Conclusion:Hepatic PEComa occurred commonly in women with obscure symptoms. The lesion was mainly single and it had no correlation with hepatitis. It is easily confused with primary liver cancer and liver metastasis on medical imagings. PEComa expressed markers of both melanocyte and smooth muscle cell, and radical surgical resection resulted in good results.

Uncommon and peculiar soft tissue sarcomas: Multidisciplinary review and practical recommendations. Spanish Group for Sarcoma research (GEIS -GROUP). Part II.

Among all Soft Tissue sarcomas there are some subtypes with low incidence and/or peculiar clinical behaviour, that need to be consider separately. Most of them are orphan diseases, whose biological characteristics imply a clearly different diagnostic and therapeutic approach from other more common sarcoma tumors. We present a brief and updated multidiciplinary review, focused on practical issues, aimed at helping clinicians in decision making. In this second part we review these subtypes: Alveolar Soft Part Sarcoma, Epithelioid Sarcoma, Clear Cell Sarcoma, Desmoplastic Small Round Cell Tumor, Rhabdoid Tumor, Phyllodes Tumor, Tenosynovial Giant Cell Tumors, Myoepithelial Tumor, Perivascular Epithelioid Cell Neoplasms (PEComas), Extraskeletal Myxoid Chondrosarcoma, NTRK-fusions Sarcomas. Most of them present their own radiological and histopathological feautures, that are essential to know in order to achieve early diagnosis. In some of them, molecular diagnosis is mandatory, not only in the diagnosis, but also to plan the treatment. On the other hand, and despite the low incidence, a great scientific research effort has been made to achieve new treatment opportunities for these patients even with approved indications. These include new treatments with targeted therapies and immunotherapy, which today represent possible therapeutic options. It is especially important to be attentive to new and potential avenues of research, and to promote the conduct of specific clinical trials for rare sarcomas.

Soft Tissue Perivascular Epithelioid Cell Tumour: An Unusual Finding.

Perivascular epithelioid cell tumour (PEComa) is a rare mesenchymal tumour made up of clear perivascular cells with epithelioid characteristics, which co-expresses muscle and melanocytic markers with a component of spindle cells, like sarcoma and variety of other tissues. This time, we present the case of a young patient with a tumour in the dorsal region of progressive growth, compatible with PEComa of soft tissue after histopathological and immunohistochemical analysis.

Malignant Subcutaneous Perivascular Epithelioid Cell Tumor of Anterior Abdominal Wall.

Perivascular epithelioid cell tumors (PEComas) are a family of rare mesenchymal tumors with discrete histological and immunohistochemical characteristics. Even rarer among them are cutaneous and subcutaneous PEComas. We describe a 34-year-old woman who presented with a large anterior abdominal subcutaneous lesion showing intact overlying skin and no obvious invasion of the abdominal musculature. A wide local excision was performed. Histopathology revealed a solitary tumor measuring 75 × 55 × 90 mm with epithelioid cells in nests with thin fibrovascular septa and spindle cells. Resection margins were clear with no invasion to the skin or rectus sheath. Tumor cells were positive for HMB-45 but negative for other markers. This is the largest subcutaneous PEComa reported to date.

A clinical study on 17 patients with liver perivascular epithelioid cell tumors / 中华肝胆外科杂志

Objective:To study the clinical manifestations and prognosis of patients with liver perivascular epithelioid cell tumor (PEComa).Methods:The clinical manifestations, imaging findings, pathological features, treatment and prognosis of 17 patients with liver PEComa managed in Shenzhen People's Hospital from September 2002 to January 2020 were retrospectively analysed.Results:The patient age of onset of liver PEComa was 22 to 54 years (average 34.8 years). There were 13 females and 4 males. 82%(14/17) of patients presented with no significant symptoms. 15/17 had solitary tumors. The diagnostic rate using preoperative B-ultrasound, CT and MRI was low. Postoperative pathological studies showed the tumor cells were mainly epithelioid cells with hyaline or eosinophilic cytoplasm. There were abundant blood vessels in the tumor tissues. Adipose tissues were also seen. Immunohistochemistry showed both HMB45 and Melan-A positivities to arrive at the diagnosis. All patients were treated with surgical resection. There were no recurrence, metastasis, or death on follow-up.Conclusion:Hepatic PEComa occurred more frequently in young women and it had no specific clinical manifestations. Except for a small number of tumors with adipose tissue detected on preoperative imagings, this tumor was difficult to diagnose, or even be suspected on preoperative imagings. Pathological examination combined with immunohistochemistry after surgery established the diagnosis. Surgery resulted in good prognosis.

Cutaneous "fibroma-like" perivascular epithelioid cell tumor: A case report and review of literature.

Perivascular epithelioid cell tumors (PEComas) are a group of lesions sharing the common features of co-expression of melanocytic and myogenic markers, with focal association of the cells with vascular walls. The PEComa group exhibits a wide range of morphologies. A "fibroma-like" variant of PEComa has been recently described. The case reported herein is that of an infant with tuberous sclerosis complex (TSC) presenting with a lip mass. Excisional biopsy showed a moderately cellular tumor composed of spindled to stellate cells embedded within a collagenized stroma. The cells showed focal perivascular accumulation and positivity for both melanocytic (HMB-45) and myogenic (desmin) markers. This is the fifth reported case of "fibroma-like" PEComa in literature and the youngest patient to date. All of the "fibroma-like" PEComas were found in patients with tuberous sclerosis-hence, the diagnosis of this entity should prompt a workup for TSC; conversely, a fibroma-like lesion in a patient with TSC or with TSC-related conditions should be evaluated using melanocytic and myogenic markers. Melanocytic and myogenic markers are also useful in differentiating "fibroma-like" PEComa from other differential diagnoses such as fibroma and benign fibrous histiocytoma.

Complexity of PEComas : Diagnostic approach, molecular background, clinical management.

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal neoplasms with features of both melanotic and smooth muscle differentiation. PEComa morphology is highly variable and encompasses epithelioid to spindle cells often with clear cytoplasm and prominent nucleoli. Molecularly, most PEComas are defined by a loss of function of the TSC1/TSC2 complex. Additionally, a distinct small subset of PEComas harboring rearrangements of the TFE3 (Xp11) gene locus has been identified. By presenting a series of three case reports with distinct features, we demonstrate diagnostic pitfalls as well as the importance of molecular work-up of PEComas because of important therapeutic consequences.

[Complexity of PEComas : Diagnostic approach, molecular background, clinical management (German version)]. / Komplexität von PEComen : Diagnose, Molekulargenetik, klinisches Management.

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal neoplasms with features of both melanotic and smooth muscle differentiation. PEComa morphology is highly variable and encompasses epithelioid to spindle cells often with clear cytoplasm and prominent nucleoli. Molecularly, most PEComas are defined by a loss of function of the TSC1/TSC2 complex. Additionally, a distinct small subset of PEComas harboring rearrangements of the TFE3 (Xp11) gene locus has been identified. By presenting a series of three case reports with distinct features, we demonstrate diagnostic pitfalls as well as the importance of molecular work-up of PEComas because of important therapeutic consequences.

[A suspected carcinoma finding in the uterus]. / Karzinomverdächtiger Herdbefund im Uterus.

Epithelioid tumor cells of a uterine perivascular epithelioid cell tumor (PEComa) may mimic carcinoma cells in an endometrial sampling (pitfall). Immunohistochemistry (HMB45 positive, keratin negative) helps in the differential diagnosis.