Imaging features of primary and metastatic malignant perivascular epithelioid cell tumors. AJR Am J Roentgenol. 2014;202:252-258. [PMID: 24450662 DOI: 10.2214/ajr.13.10909]

Clinical and ultrasound features of uterine perivascular epithelioid cell tumors: case series and literature review

OBJECTIVE

To describe the clinical and ultrasonographic features of uterine perivascular epithelioid cell tumor (PEComa) using standardized terminology.

METHODS

This was a retrospective analysis of patients with uterine PEComa diagnosed and confirmed by pathology and immunohistochemistry at West China Second University Hospital, Sichuan University, Sichuan, China, between January 2010 and September 2023. The Morphological Uterus Sonographic Assessment (MUSA) consensus and the International Endometrial Tumor Analysis (IETA) consensus were utilized for the standardized description of the sonographic characteristics of uterine PEComa. We summarized the clinical and ultrasound features of uterine PEComa in cases from our center and those found in a review of the literature conducted using PubMed from 1 January 2013 to 30 September 2023 (inclusive).

RESULTS

Five patients, aged 33-57 (median, 52) years, with a total of six uterine PEComa lesions were included in our cohort. All cases had complete ultrasonographic and pathological images. None of the patients had a history of tuberous sclerosis complex. Two patients had malignant PEComa (one patient had two lesions) and three had benign PEComa, originating from the cervix, myometrium or uterine cavity. Patients presented with symptoms including increased vaginal discharge, vaginal bleeding and pelvic or abdominal pain. The three patients with benign PEComa underwent total hysterectomy and bilateral adnexectomy, tumor excision and conservative management, respectively, while both malignant cases underwent total hysterectomy and bilateral adnexectomy followed by chemotherapy. Regular follow-up (from 6 to 24 months) revealed recurrence in one case. Two lesions were misdiagnosed as uterine fibroids, two as cervical cancer, one as metastatic cervical cancer (with myometrial invasion) and one was indeterminate. Ultrasound examination showed that most lesions displayed regular round or ovoid shape (66.7%), uniform echoes (66.7%) and hypoechogenicity (66.7%), with one (16.7%) malignant PEComa showing cystic areas and one (16.7%) benign PEComa showing punctate calcifications. All lesions lacked shadowing and the majority showed moderate to abundant vascularity (color score of 3-4, 83.3%). The color score was 2-4 in the periphery in 100% of cases and internally in 83.3% of cases. The three benign PEComas showed similar characteristics in vascular distribution, with scattered internal vessels and peripheral vessels exhibiting a circular pattern. The literature search identified 11 articles describing the ultrasonographic appearance of 18 cases of uterine PEComa, with similar characteristics to those in our cohort.

CONCLUSIONS

The sonographic features of uterine PEComa include a uniform or non-uniform hypoechogenic mass, typically round or ovoid with regular margins, occasionally containing cystic areas or calcifications, lacking shadowing and often showing moderate to abundant vascularity. Although the preoperative ultrasound diagnosis of uterine PEComa remains challenging, particularly given the non-specific nature of the sonographic characteristics described here, dispersed intratumoral vessels and a peripheral circular vascular distribution may serve as diagnostic clues for uterine PEComa, but more cases are needed for confirmation. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Massive simultaneous hepatic and renal perivascular epithelioid cell tumor benefitted from surgery and everolimus treatment: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that predominantly affects the kidney and uterus. The occurrence of this tumor in the liver, particularly with simultaneous involvement of the liver and kidney, is exceedingly uncommon. Pathological diagnosis is the gold standard. PEComas usually show positive immunohistochemical staining for melanocytic (HMB-45, Melan-A) and myoid (SMA, muscle-specific actin) markers.

CASE SUMMARY

We presented a noteworthy case of malignant PEComa affecting both the liver and kidney in a 53-year-old man with tuberous sclerosis complex (TSC). FAT2 and TP73 mutations in the kidney were identified and positive expression of diagnostic markers including HMB-45, Melan A, and TFE3 were detected. In addition, we demonstrated that hepatic artery perfusion chemotherapy was ineffective for hepatic PEComa, while surgery remained the most effective approach. Everolimus showed an excellent efficacy in the postoperative treatment of the tumor.

CONCLUSION

Surgical treatment is preferred for malignant PEComa affecting liver and kidney, especially with TSC; everolimus is effective postoperatively.

PEComas: A review of imaging and clinical features

Perivascular epithelioid cell tumors (PEComas) are a group of rare mesenchymal tumors, which demonstrate varied imaging appearances and treatment options. These tumors may arise de novo or in the setting of systemic disorders, such as tuberous sclerosis. Some PEComas are benign and easily resected while others may represent systemic or metastatic disease with limited therapeutic options. The purpose of this review is to introduce the topic of perivascular epithelioid cell tumors and the most common tumors within the PEComa family as well as discuss the epidemiology, morphology, radiographic appearance, and treatment options of these rare tumors.

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.

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.

Non-gastrointestinal stromal tumor, mesenchymal neoplasms of the gastrointestinal tract: a review of tumor genetics, pathology, and cross-sectional imaging findings

There is a diverse group of non-gastrointestinal stromal tumor (GIST), mesenchymal neoplasms of the gastrointestinal (GI) tract that demonstrate characteristic pathology and histogenesis as well as variable imaging findings and biological behavior. Recent advancements in tumor genetics have unveiled specific abnormalities associated with certain tumors, influencing their molecular pathogenesis, biology, response to treatment, and prognosis. Notably, giant fibrovascular polyps of the esophagus, identified through MDM2 gene amplifications, are now classified as liposarcomas. Some tumors exhibit distinctive patterns of disease distribution. Glomus tumors and plexiform fibromyxomas exhibit a pronounced affinity for the gastric antrum. In contrast, smooth muscle tumors within the GI tract are predominantly found in the esophagus and colorectum, surpassing the incidence of GISTs in these locations. Surgical resection suffices for symptomatic benign tumors; multimodality treatment may be necessary for frank sarcomas. This article aims to elucidate the cross-sectional imaging findings associated with a wide spectrum of these tumors, providing insights that align with their histopathological features.

Systematic analysis of perivascular epithelioid cell neoplasms in the female reproductive tract: a comprehensive review

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal lesions, with gynecological PEComas accounting for just over a quarter of cases. Limited reports exist on gynecological PEComa, primarily treated with surgery; adjuvant therapy is considered in high-risk cases. This systematic review aims to summarize the origin and clinical, pathological and molecular characteristics of uterine PEComa, focusing on treatment options for gynecological PEComa. A comprehensive PubMed review of gynecological PEComa reports was conducted. A detailed examination of the literature ensured a thorough understanding. Gynecological PEComa diagnosis relies on histology and immunology. Despite therapy controversies, surgery remains the mainstay. Adjuvant therapy efficacy in high-risk cases is uncertain. mTOR inhibitors are the first line; alternative treatments, including angiogenesis and aromatase inhibitors, should be considered.

Practical Management of Adult Ultra-Rare Primary Retroperitoneal Soft Tissue Sarcoma: A Focus on Perivascular Epithelioid Tumours and Extraosseous Ewing Sarcoma

With the exception of well-differentiated liposarcoma, dedifferentiated liposarcoma, leiomyosarcoma, solitary fibrous tumour, malignant peripheral nerve sheath tumour, and undifferentiated pleomorphic sarcoma, the majority of the ≈70 histologic subtypes of retroperitoneal sarcoma are defined as 'ultra-rare' sarcomas, with an incidence of ≤1-5/1,000,000 persons/year. For most of these ultra-rare RPS subtypes, diagnosis and treatment follows international guidelines for the management of more common RPS histologies, with en bloc surgical resection as the mainstay of curative treatment, and enrolment in clinical trials where possible. Because the treatment of RPS is heavily driven by histology, the surgeon must be familiar with specific issues related to the diagnosis and management of ultra-rare sarcoma subtypes. Expert radiological and surgeon reviews are required to differentiate similarly presenting tumours where surgery can be avoided (e.g., angiomyolipoma), or where upfront systemic therapy is indicated (e.g., extraosseous Ewing's sarcoma). Thus, the management of all retroperitoneal sarcomas should occur at a sarcoma referral centre, with a multidisciplinary team of experts dedicated to the surgical and medical management of these rare tumours. In this focused review, we highlight how diagnosis and management of the ultra-rare primary RPS histologies of malignant perivascular epithelioid cell tumour (PEComa), extraosseous Ewing sarcoma (EES), extraosseous osteosarcoma (EOS), and rhabdomyosarcoma (RMS) critically diverge from the management of more common RPS subtypes.

Acute haemorrhage from a large renal epithelioid angiomyolipoma: diagnostic and management considerations in a teenage patient with a rare cancer

Acute renal haemorrhage is a life-threatening condition that is complicated in the context of renal malignancy. Here, we present the case of a teenage male presenting acutely with a large, bleeding renal epithelioid angiomyolipoma (EAML) of the kidney-a rare cancer, which is part of the perivascular epithelioid cell tumour family. The patient was managed acutely with prompt resuscitation, transfer to a centre of expertise and haemorrhagic control using radiologically guided endovascular techniques; this subsequently permitted an oncologically sound procedure (radical nephrectomy, inferior vena cava thrombectomy and lymphadenectomy) to be performed within 24 hours. The description and discussion around this unique case summarises the patient's clinical journey, while exploring the current literature surrounding diagnosis and outcomes of patients with renal EAMLs.

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.

Perivascular epithelioid cell tumor (PEComa) of the cystic duct

Perivascular epithelioid cell tumors, also known as PEComas, are rare mesenchymal tumors composed mainly of epithelioid cells found in perivascular tissue. PEComas occur most frequently in the kidney, uterus, the gastrointestinal tract, liver, and retroperitoneum; those originating in the biliary tree are extremely rare. We report a case of benign PEComa of the cystic duct with positive TFE3 staining on immunohistochemistry.A 66-year-old woman was referred for a 20 mm mass adjacent to the common bile duct discovered incidentally on abdominal ultrasound. Laboratory data including tumor markers were unremarkable. The tumor appeared to arise from the cystic duct, showed early enhancement, and compressed the common bile duct on imaging studies. Endoscopic ultrasound-guided fine-needle aspiration revealed round- and spindle-shaped atypical cells with eosinophilic cytoplasm and brown deposits suggestive of melanin granules. Histological examination of the resected specimen revealed a tumor consisting of epithelioid cells forming an alveolar structure, with melanin pigmentation. Immunohistochemistry was positive for HMB-45 and TFE3, consistent with benign pigmented PEComa of the cystic duct. Melanotic, myogenic, and TFE3 staining are helpful when diagnosing PEComas arising in unusual locations.

Malignant perivascular epithelioid cell tumor (PEComa) of the uterus

BACKGROUND

Perivascular epithelioid cell tumors (PEComas) of the uterus is a rare type of mesenchymal tumors associated with myelomelanocytic differentiation and distinctive histological appearances. So far, the reported cases of uterine PEComas are usually benign. Documented malignant cases with aggressive behavior appear to be less common.

CASE PRESENTATION

We report a 37-year-old female who received abdominal hysterectomy for uterine tumor in a local hospital. She was diagnosed with uterine leiomyosarcoma and referred to Hubei Cancer Hospital. Her histological slides were reviewed and immunohistochemical staining for specific markers of epithelial, melanocytic, myoid and some others were analyzed. The pathologic diagnosis was malignant uterine PEComa. Systematic imaging of the patient further revealed an abdominal para-aortic mass. She received pelvic and para-aortic lymph node dissection. Postoperative histology revealed para-aortic lymph nodal metastasis of malignant uterine PEComa. She received 8 cycles of chemotherapy after surgery. The chemotherapy regiment was epirubicin plus ifosfamide The patient is free of recurrence and metastasis 6 years after surgical resection.

CONCLUSION

Uterine PEComas are indistinguishable from other uterine tumors such as leiomyoma and leiomyosarcoma before pathologic diagnosis could be made. For patients with malignant uterine PEComas, removal of both primary lesions and metastatic foci, if any, needs to be attempted. Postoperative chemotherapy or radiotherapy should also be considered in patients with distant metastases or positive lymph nodes.

Renal and mediastinal perivascular epithelioid cell tumors (PEComas) in a young child with Tuberous Sclerosis; a rare case report

We describe a unique case of perivascular epithelioid cell tumors PEComas occurring as mediastinal and left renal soft tissue masses discovered incidentally in a five-year-old Tuberous Sclerosis patient upon presentation to the emergency department for upper respiratory illness. The radiographic features were non-specific. However, the similar CT characteristics of both lesions and background history raised the suspicion of a synchronous mesenchymal tumor, and histopathology confirmed the diagnosis. The rarity of these tumors in the pediatric population and lack of specific diagnostic criteria impose reporting the case and emphasize the need for further research on imaging features of such tumors.

Primary retroperitoneal PEComa: an incidental finding

Perivascular epithelioid cell neoplasm (PEComa) is a rare type of tumour, and primary retroperitoneal PEComa is rarer still. Although pulmonary lymphangioleiomyomatosis (LAM), angiomyolipomas and clear cell 'sugar' tumours of the lung are well described, relatively little is known about other members of the PEComa family. We describe a case of an asymptomatic retroperitoneal PEComa, lymphangioleiomyoma type, which appeared in a previously healthy middle-aged woman as an incidental finding, in a CT scan performed in the context of spontaneous pneumothorax. The patient underwent surgical excision of the tumour and the histopathological and immunohistochemical analysis of the surgical specimen made the definitive diagnosis. Although rare, reports of isolated retroperitoneal lymphangioleiomyoma and primary retroperitoneal PEComas NOS (not otherwise specified) are described in the literature, normally associated with pulmonary LAM. The patient's pulmonary imaging was normal. Short-term re-examination did not detect any recurrence. We also provide a literature review of this rare group of tumours.

Sclerosing Perivascular Epithelioid Cell Tumor of the Uterus: A Rare Entity Posing Diagnostic Challenge

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal uterine tumor and the histological variant, sclerosing PEComa is exceedingly rare. Sclerosing PEComas preferentially occur in the retroperitoneum and occurrence in the uterine corpus is seldom seen. These tumors pose a diagnostic challenge and need distinction from morphological mimickers such as epithelioid smooth muscle tumors, endometrial stromal sarcoma, and metastatic carcinoma. Accurate diagnosis can be established coupling histomorphology with immunostaining. The distinction from other entities is of prime importance considering the therapeutic and prognostic implications. Herein, we describe a case of uterine sclerosing variant of PEComa with diagnostic difficulties and key to diagnose this entity.

Perivascular epithelioid cell tumour-mimicking retroperitoneal leiomyosarcoma

A young man in his 40s was evaluated in the emergency department for abdominal and right flank pain. A CT scan of the abdomen and pelvis showed a solid, well-circumscribed lesion measuring 7.1×8.1×5.4 cm, which was arising from the retroperitoneum and extending from the third portion of the duodenum towards the right kidney. A percutaneous core biopsy was obtained, demonstrating an atypical smooth muscle neoplasm suggestive of a low-grade leiomyosarcoma. The patient underwent surgery for an en-block resection of the mass and the final pathology confirmed a perivascular epithelioid cell neoplasm without significant pleomorphism, mitosis or necrosis. Our case adds to the small number of perivascular epithelioid cell tumour cases reported in the literature and we present it in order to increase our understanding of this tumour and to assist in its appropriate diagnosis and management.

Mesenchymal neoplasms of the urinary bladder: a comprehensive review with focus on cross-sectional imaging findings

Mesenchymal neoplasms of the urinary bladder are exceedingly rare and display remarkable diversity. These tumors demonstrate distinct pathological features as well as variable biological behavior and cross-sectional imaging findings. The rarity of tumors, nonspecific symptoms and seemingly normal cystoscopic findings (particularly with small and exophytic tumors) frequently lead to misdiagnosis or missed diagnosis. While some tumors display characteristic cross-sectional imaging findings that may suggest a diagnosis, imaging findings are mostly nonspecific. Histopathological examination is required for accurate diagnosis, management and prognostication. The purpose of this article is to review the cross-sectional imaging findings of a diverse spectrum of mesenchymal tumors of the urinary bladder.

Renal Neoplasms in Young Adults

Renal cell carcinoma (RCC) is usually diagnosed in older adults (the median age of diagnosis is 64 years). Although less common in patients younger than 45 years, RCCs in young adults differ in clinical manifestation, pathologic diagnosis, and prognosis. RCCs in young adults are typically smaller, are more organ confined, and manifest at lower stages of disease. The proportion of clear cell RCC is lower in young adults, while the prevalence of familial renal neoplastic syndromes is much higher, and genetic testing is routinely recommended. In such syndromic manifestations, benign-appearing renal cysts can harbor malignancy. Radiologists need to be familiar with the differences of RCCs in young adults and apply an altered approach to diagnosis, treatment, and surveillance. For sporadic renal neoplasms, biopsy and active surveillance are less often used in young adults than in older adults. RCCs in young adults are overall associated with better disease-specific survival after surgical treatment, and minimally invasive nephron-sparing treatment options are preferred. However, surveillance schedules, need for biopsy, decision for an initial period of active surveillance, type of surgery (enucleation or wide-margin partial nephrectomy), and utilization of ablative therapy depend on the presence and type of underlying familial renal neoplastic syndrome. In this pictorial review, syndromic, nonsyndromic, and newer RCC entities that are common in young adults are presented. Their associated unique epidemiology, characteristic imaging and pathologic traits, and key aspects of surveillance and management of renal neoplasms in young adults are discussed. The vital role of the informed radiologist in the multidisciplinary management of RCCs in young adults is highlighted. Online supplemental material is available for this article. ^©RSNA, 2022.

Tuberous Sclerosis Complex (TSC): Renal and Extrarenal Imaging

Tuberous sclerosis complex is a multiorgan syndrome manifesting with several benign and malignant tumors. Complications arising from renal abnormalities are a leading cause of death in patients with tuberous sclerosis complex. Renal cell carcinoma is relatively uncommon, occurring in 2%-4% of patients with tuberous sclerosis complex syndrome, but nonetheless can significantly contribute to morbidity and mortality. Extrarenal manifestations of tuberous sclerosis complex, including within the chest, abdomen and central nervous system, aid in diagnosis. Pathogenesis and management are also discussed, including the importance of the types of renal masses found in these patients.

Mesenchymal Neoplasms of the Prostate and Seminal Vesicles: Spectrum of Disease with Radiologic-Pathologic Correlation

There is a wide spectrum of benign and malignant mesenchymal neoplasms of the prostate, which account for less than 1% of all prostatic tumors. These include distinctive tumors that arise from the specialized prostatic stroma and site-agnostic neoplasms such as smooth muscle tumors, fibrous or myofibroblastic neoplasms, neurogenic tumors, vascular tumors, and a plethora of sarcomas. Select tumors show classic sites of origin within the prostate. While stromal tumors of uncertain malignant potential (STUMPs) commonly involve the peripheral zone at the prostate base, leiomyomas typically originate from the central prostate toward the apex. Some "prostatic" neoplasms such as gastrointestinal stromal tumors, solitary fibrous tumor (SFT), paragangliomas, and neurogenic tumors arise primarily from periprostatic soft tissues. Most mesenchymal tumors of the prostate and seminal vesicles manifest as large tumors that cause nonspecific symptoms; prostate-specific antigen level is not typically elevated. Diverse mesenchymal neoplasms demonstrate characteristic histopathologic and immunocytochemical features and variable cross-sectional imaging findings. While leiomyoma and SFT typically display low signal intensity on T2-weighted images, synovial sarcomas commonly show hemorrhage. Diagnosis is difficult because of the rarity and lack of awareness of the tumors and the significant overlap in histopathologic features. Select tumors show characteristic genetic abnormalities that allow the diagnosis to be established. For example, more than 90% of SFTs are characterized by a unique NAB2-STAT6 gene fusion, and more than 95% of synovial sarcomas are associated with a distinctive SYT-SSX chimeric transcript. Accurate diagnosis is imperative for optimal management owing to markedly different tumor biology as well as attendant therapeutic and prognostic implications. While STUMPs commonly recur, sarcomas typically charter an aggressive course with poor prognosis. Online supplemental material is available for this article. ^©RSNA, 2022.

Acute and repeated haemoperitoneum: a challenging case of lymphangioleiomyomatosis with uterine PEComa

A 39-year-old woman presented in the emergency ward for abdominal pain and acute anemiation. Abdominal-thoracic CT scan showed haemoperitoneum, with a parauterine mass and a pathological pulmonary pattern suspicious for lymphangioleiomyomatosis (LAM), a systemic disease belonging to perivascular epithelioid cell tumours (PEComas). Gynaecological ultrasound showed a hypoechoic irregular solid mass of the uterine right wall. Ultrasonographic virtual organ computer-aided analysis showed the mass completely formed by arteriovenous vessels, and that allowed distinction from leiomyosarcoma. Repeated haemoperitoneum required uterine artery embolisation. Mass revascularisation occurred in the following 7 days. A laparotomic hysterectomy with removal of the uterus and right parametrium was performed in epidural analgesia. Histological features were consistent with the diagnosis of uterine PEComa of uncertain malignant features, in the presence of coexisting pulmonary LAM. In women with LAM, acute haemoperitoneum may indicate the presence of a uterine PEComa whose diagnosis can be challenging.

Natural History and Treatment Strategies of Advanced PEComas: A Systematic Review

Simple Summary

In this article, we review the clinical features of advanced PEComas and show the diversity of reported data among authors, emphasizing the heterogeneity of molecular characterization and treatment strategy. Based on clinical data collected from 124 case reports, metastatic disease at diagnosis and a grouped version of the Bleeker’s risk category were the only factors significantly associated with death. Due to a significant number of missing data or short follow-ups, results regarding prognostic factors should, however, be interpreted with caution.

Abstract

PEComas is a family of rare mesenchymal tumors. This systematic review aims to better understand the natural history of advanced PEComas. After a search on the PubMed database and main oncology meeting libraries according to the PRISMA guidelines, 88 articles reported in the English literature were included. Data on clinical and histological features, treatments and outcomes were collected. To identify risk factors, univariate and multivariate analyses were performed. Seven cohorts of patients and 124 individual patients were identified. Focusing on case reports, most patients were metastatic, and the median overall survival (OS) of the entire cohort was 60 months (95%CI 33; NA). Risk factors significantly associated with OS in the multivariate analysis were the presence of metastasis at diagnosis (HR: 2.59, 95%CI 1.06; 6.33, p = 0.036) and the grouped-Bleeker’s risk category (HR: 4.66; 95%CI 1.07; 20.19; p = 0.039). In the metastatic population, only the presence of lymph node metastasis was associated with OS (HR: 3.11; 95%CI 1.13; 8.60, p < 0.05). Due to a lack of events, it was not possible to conclude on other factors. This review of the literature highlights the heterogeneity of literature data and shows the great diversity of clinical management strategies.

Efficacy of Sirolimus Treatment in PEComa-10 Years of Practice Perspective

Perivascular epithelioid cell tumors (PEComa) represent a family of rare mesenchymal tumors resultant from deregulation in mTOR pathway activity. The aim of this study is to evaluate the long-term efficacy of targeted PEComa treatment. We reviewed all consecutive patients with PEComa who started systemic treatment with sirolimus in our reference sarcoma center between January 2011 and August 2020. Histopathology of PEComa was reviewed and confirmed in all cases by a designated sarcoma pathologist. Any surviving progression-free patients were censored at the last follow-up (31 March 2021). Survival curves were calculated according to Kaplan-Meier method and compared with the log-rank test or a Cox proportional hazard model. Fifteen (12 females and 3 males) consecutive PEComa patients were treated. The median age of patients treated systemically was 50 years. Median progression-free survival (PFS) was 4.9 months (95% CI: 3.8-NA) for first-line chemotherapy and was not reached (95% CI: 42.0-NA) for sirolimus as first-line therapy. There was one objective response (OR) in the chemotherapy group. The OR rate reached 73% (11/15 cases) for sirolimus regardless of the treatment line. All patients archived disease control. Three patients died due to disease progression after 55, 32, and 32 months since metastatic disease diagnosis. After a median follow-up of 55.7 (range: 3.2-220) months, the 5 yr OS was 65% (CI 95% 39-100). Our study is the largest single-institution report on PEComa systemic targeted therapy and fills the gap in the field of advanced PEComa care since the FDA/EMEA approval of sirolimus.

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.

18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Response Assessment of Perivascular Epithelioid Cell Tumor of the Pelvic Cavity to Irinotecan and Temozolomide

Perivascular epithelioid cell tumors (PEComas) are a rare variety of mesenchymal tumors composed of distinctive cells that show a focal association with blood vessel walls and usually express melanocytic and smooth muscle markers. We present a case of 38-year-old male, diagnosed with PEComa of the pelvic cavity who underwent serial ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography scans for the assessment of response to the chemotherapeutic combination of irinotecan and temozolomide.

Primary perivascular epithelioid cell tumor (PEComa) in bone: A review of the literature and a case arising in the humerus with multiple metastases

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First case PEComa primary arising in humerus was described.

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Histology is the basic to determine malignancy of PEComa.

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TFE3 gene investigation is the key of therapy selection.

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mTOR inhibitor is believed to be effective for patients without TFE3 rearrangement.

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More study is needed to understand the role of molecular test and imaging in PEComa.

Introduction

Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal tumors that rarely arise as a primary bone tumor.

Material and methods

We report a case of primary malignant bone PEComa. A literature review via PubMed, Embase and Web of Science databases with the keyword “PEComa” and “bone” was performed.

Results

We reported a 33-year-old female with primary malignant bone PEComa in right distal humerus. The patient received an inhibitor of the mammalian target of rapamycin (mTOR) protein based on negative molecular investigation result of transcription factor E3 (TFE3) rearrangement, and additional therapies including palliative radiotherapy, anti-angiogenics and immunotherapy when the disease progression was detected. The patient was alive with the disease twenty-three months postoperatively. A total of nineteen related literature cases were retrieved and reviewed. Taking current case into account, ten males and ten females with median age of 24 years (range, 3–93 years) were identified, who were most frequently affected in tibia. The median follow-up duration of 24 months (range, 3–96 months). One patient died due to this disease, and six patients showed metastases. Three patients experienced recurrence, and two of them experienced twice and three times, respectively.

Conclusion

To our knowledge, this is the first case of primary malignant bone PEComa arising in humerus. Clinicopathological and radiological correlation is mandatory to the correct diagnosis and to determine its malignancy. More studies are required to understand the role of molecular test and imaging in selecting suitable treatment and mechanisms of treatment resistance.

Ultrasound Features of a Uterine Perivascular Epithelioid Cell Tumor (PEComa): Case Report and Literature Review

Background: Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors. One of the most frequent localizations of PEComas is the female genitourinary tract, and the uterus is the most involved site after the kidney. Correct preoperative diagnosis is rarely achieved due to the presence of nonspecific imaging features. We report a case of a uterine PEComa with particular reference to ultrasound’s role in characterizing this rare occurrence. Case presentation: a 45-year-old White woman came to our observation for cyclic abdominopelvic pain and chronic constipation. The pre-surgical ultrasound examination showed a heterogeneous tumor that was 4 cm in size, localized on the right anterolateral uterine wall. The mass had well-delimited borders and a central hypoechoic portion. The use of color Doppler showed a rich, irregular vasculature in the center with low impedance. The preoperative diagnostic hypothesis was of a smooth muscle tumor of uncertain malignant potential. After careful counseling, a surgical approach was decided upon, including a total laparoscopic hysterectomy with bilateral salpingectomy. The histological and phenotypical features were consistent with a uterine PEComa. At the last follow-up, two years after surgery, the patient is alive and well. Conclusions: Uterine PEComa is a rare occurrence that should be included in the differential diagnosis of uterine wall tumors. It can appear as a small uterine mass with heterogeneous echogenicity and a rich vascular pattern during an ultrasound evaluation. This diagnostic suspicion may assist in better surgical planning.

Abdominal perivascular epithelioid cell tumor (PEComa) without visible fat: a clinicopathologic and radiological analysis of 16 cases

OBJECTIVE

To retrospectively review the clinicopathological features and computed tomography (CT) and magnetic resonance imaging (MRI) findings of abdominal perivascular epithelioid cell tumor without visible fat (PEComa_wvf).

MATERIALS AND METHODS

Sixteen patients with surgically and pathologically confirmed perivascular epithelioid cell tumor without visible fat were enrolled. Their clinicopathological data and imaging findings were retrospectively reviewed. The CT and MRI features, including location, size, shape, margin, density, calcification, cystic necrosis and enhancement pattern, were analyzed.

RESULTS

There were 4 males and 12 females (median age, 46 years; range, 21-65 years) in this study. All 16 patients were diagnostic asymptomatic unenhanced CT or MRI and revealed a well-defined (n = 13), oval (n = 10), mass with heterogeneous (n = 6) or homogeneous density/signal intensity (n = 7), calcification and hemorrhage was no found in any cases. On enhanced CT/MRI, markedly enhancement patterns (n = 14) were observed. The "peripheral enhancement" sign was observed in 13 cases. One in 16 cases recurrence was discovered during the follow-up period.

CONCLUSIONS

Dynamic CT, MRI and pathology of PEComa_wvf had some characteristics of non-aggressive pattern of performance, and MRI would provide beneficial detection of microscopic fat. Enhanced imaging showed PEComa_wvf is characterized by a "peripheral enhancement" with a marked enhancement pattern. Knowing these characteristics could contribute to improving the understanding abdominal PEComa_wvf and related palliative care.

Perivascular epithelioid cell tumors (PEComa) in pregnancy with uterine rupture and ongoing abdominal gestation: A case report

Perivascular epithelioid cell tumors (PEComa) represent a rare family of tumors characterized by distinct histology and immunohistochemistry characteristics. Approximately one-quarter of reported cases are gynecologic in origin and associated pregnancies are rare. We report a case of PEComa in pregnancy with initial undiagnosed presentation at 18 weeks of gestation and subsequent presentation and diagnosis at 30 weeks of gestation. Abdominal pain led to the use of magnetic resonance imaging, which raised concerns about placentation abnormality and abdominal pregnancy. Exploratory laparotomy was notable for a 10 cm by 15 cm posterior uterine defect through which the placenta and amniotic sac containing the fetus were extruded. Placenta-like tissue was noted to be invading through the anterior wall of the uterus, which led to concern regarding placenta percreta. A total abdominal hysterectomy and bilateral salpingectomy were then performed, given the complete loss of normal uterine architecture. Pathology returned with findings of placenta accreta and PEComa. Indolent uterine rupture in the setting of PEComa led to an ongoing viable abdominal pregnancy. Uterine PEComa can masquerade as a placenta and lead to obstetrical complications.

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Perivascular epithelioid cell tumors (PEComa) can masquerade as a placenta.

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Perivascular epithelioid cell tumors can lead to uterine rupture during pregnancy.

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Uterine perivascular epithelioid cell tumors can be associated with tuberous sclerosis complex.

A rare case of perivascular epithelioid cell tumor (PEComa) of the pancreas diagnosed by endoscopic ultrasound

A 49-year-old woman consulted her general practitioner (GP) regarding epigastric pain that she had experienced for 2 months. Physical examination and laboratory results were unremarkable. An abdominal ultrasound indicated a solid pancreatic tumor, which was confirmed on subsequent CT and MRI. Endoscopic ultrasound (EUS) showed a well-defined heterogeneous, predominantly hypoechoic mass in the pancreatic body, so a neuroendocrine tumor (NET) was suspected. However, EUS-guided fine-needle aspiration (EUS-FNA) was performed and based on (immuno-)histochemical findings, the extremely rare diagnosis of a perivascular epithelioid cell tumor (PEComa) of the pancreas was made. Due to the malignant potential of pancreatic PEComas, laparoscopic left-sided pancreatectomy was performed. We present a case diagnosed by preoperative EUS-FNA highlighting the clinical and endosonographic features which help to distinguish it from its most important differential diagnosis, neuroendocrine tumors (NETs) of the pancreas.

Lung Masses of Unusual Histologies Mimicking Malignancy: Flurodeoxyglucose Positron Emission Tomography-Computed Tomography Appearance

18F flurodeoxyglucose positron emission tomography-computed tomography (18F FDG PET-CT) is widely used in the evaluation of patients with lung mass suspicious for malignancy. In addition to malignancy, a variety of benign neoplasms and inflammatory lesions can arise in the lungs, many of which show increased FDG concentration, thereby mimicking malignancy. Awareness of the common mimics of lung cancer and a thorough understanding of their key imaging characteristics on CT as well as FDG PET is helpful in narrowing the differential diagnosis, eventually leading to appropriate therapy. In this article, we enlist these mimics and discuss their metabolic and morphologic characteristics and provide a pathophysiological basis for their FDG uptake.

[Hepatic epithelioid angiomyolipoma/PEComa and focal nodular hyperplasia in a patient with a previous history of cutaneous melanoma]

Hepatic perivascular epithelioid cell tumors (PEComas) are uncommon mesenchymal neoplasms. PEComas concurrent with other hepatic lesions is a very rare occurrence, with only two previously reported cases. We report a primary hepatic PEComa associated with focal nodular hyperplasia in a patient with a previous history of cutaneous melanoma. Diagnostic imaging studies suggested a hepatic adenoma and the patient underwent a segmentectomy. The tumor was mainly composed of epithelioid cells, adipose tissue and smooth muscle fibers intermixed with blood vessels. The neoplastic cells were diffusely immunoreactive for HMB-45, Melan-A and smooth muscle actin, but not for Hepatocyte, S100, MITF or BRAF. Molecular studies were negative for BRAFV600 mutation. The final diagnosis was hepatic epithelioid angiomyolipoma/PEComa. The differential diagnosis of hepatic PEComa is discussed.

Primary hepatic perivascular epithelioid cell tumors: imaging findings with histopathological correlation

Background

Hepatic PEComas are very rare. Few systematic reports are available characterizing the imaging and pathological features of hepatic PEComa. The aim of this study was to investigate the imaging findings of primary hepatic perivascular epithelioid cell tumors (PEComa) and its correlation with histopathological features.

Methods

The CT, MRI and ultrasound images and pathological findings of 22 patients with primary hepatic PEComa were retrospectively reviewed.

Results

More females (14/22) were affected with the mean age of 47.1 years. Most patients (17/22) were asymptomatic and the routine laboratory tests were normal. More tumors occurred in the right lobe (13/22) with a mean diameter of 76.7 mm. Surgery was performed in 21 patients, and biopsy was performed in 1 patient. Immunohistochemical studies showed the expression rate of HMB-45 and Melan A was 100% (22/22) and 86.4% (19/22) within the tumor cells. The pathology diagnoses were angiomyolipoma (n = 18), lymphangioleiomyoma (n = 2), clear-cell myomelanocytic tumor of falciform ligament/ligamentum teres (n = 1), and not otherwise specified (n = 1). Fifteen cases were classified as uncertain malignant potential (n = 13) or malignant (n = 2). CT, MRI and ultrasound features included well-defined margins (19/22), internal heterogeneity (20/22), arterial enhancement (20/22), dysmorphic vessels (17/22), fat (9/22), hemorrhage (3/22), necrosis (8/22), and calcification (2/22). The diagnostic accuracy was only 27.3% (6/22). No local recurrence or metastasis was found in the follow-up patients (12/22).

Conclusions

On CT, MRI and ultrasound images, most hepatic PEComas are well-defined, heterogeneous, arterial enhanced masses with dysmorphic vessels, with or without fat, especially in middle-aged females. With the potential to be malignant, timely surgical resection and long-term follow-up may be helpful for improving the prognosis.

Ischiorectal fossa: benign and malignant neoplasms of this "ignored" radiological anatomical space

PURPOSE

To review the pertinent anatomy and the imaging features of common and uncommon benign and malignant neoplasms and masses of the ischiorectal fossa.

RESULTS

The ischiorectal or ischioanal fossa is the largest space in the anorectal region. The benign neoplasms that develop in the ischiorectal originate from the different components that forms the fossa including vascular tumors such as aggressive angiomyxoma or hemangioma; neural tumors as plexiform neurofibroma or schwannoma; fat tumors as lipoma; skin/skin appendages tumors as hidradenoma papilliferum; smooth or skeletal muscle tumors as solitary fibrous tumor. The malignant neoplasms that develop in the ischiorectal fossa also originate from different components that forms the fossa including vascular tumors such as angiosarcoma, neural tumors as malignant granular cell tumor and malignant peripheral nerve sheath tumor; fat tumors as liposarcoma; smooth or skeletal muscle tumors as leiomyosarcoma, rhabdomyosarcoma, malignant PEComa, or undifferentiated pleomorphic sarcoma. Additionally, the ischiorectal fossa can also harbor secondary hematogenous metastases and be affected by direct invasion from neoplasms of adjacent pelvic organs and structures. Furthermore, other miscellaneous masses can occur in the ischiorectal fossa including congenital and developmental lesions, and inflammatory and infectious processes.

CONCLUSION

Knowledge of the anatomy, and the spectrum of imaging findings of common and uncommon benign and malignant neoplasms of the ischiorectal fossa is crucial for the radiologists during interpretation of images allowing them to make contributions to the diagnosis and better patient management.

Malignant hepatic vascular tumors in adults: Characteristics, diagnostic difficulties and current management

Malignant vascular tumors of the liver include rare primary hepatic mesenchymal tumors developed in the background of a normal liver parenchyma. Most of them are detected incidentally by the increased use of performing imaging techniques. Their diagnosis is challenging, involving clinical and imaging criteria, with final confirmation by histology and immunohistochemistry. Surgery represents the mainstay of treatment. Liver transplantation (LT) has improved substantially the prognosis of hepatic epithelioid hemangioendothelioma (HEHE), with 5-year patient survival rates of up to 81%, based on the European Liver Intestine Transplantation Association-European Liver Transplant Registry study. Unfortunately, the results of surgery and LT are dismal in cases of hepatic angiosarcoma (HAS). Due to the disappointing results of very short survival periods of approximately 6-7 mo after LT, because of tumor recurrence and rapid progression of the disease, HAS is considered an absolute contraindication to LT. Recurrences after surgical resection are high in cases of HEHE and invariably present in cases of HAS. The discovery of reliable prognostic markers and the elaboration of prognostic scores following LT are needed to provide the best therapeutic choice for each patient. Studies on a few patients have demonstrated the stabilization of the disease in a proportion of patients with hepatic vascular tumors using novel targeted antiangiogenic agents, cytokines or immunotherapy. These new approaches, alone or in combination with other therapeutic modalities, such as surgery and classical chemotherapy, need further investigation to assess their role in prolonging patient survival. Personalized therapeutic algorithms according to the histopathological features, behavior, molecular biology and genetics of the tumors should be elaborated in the near future for the management of patients diagnosed with primary malignant vascular tumors of the liver.

A rare case of perivascular epithelioid cell tumor (PEComa) of the greater omentum

Background

A tumor composed exclusively or predominantly of human melanin black 45 (HMB45)-positive epithelioid cells is called a perivascular epithelioid cell tumor (PEComa). We report a very rare case of a PEComa of the greater omentum.

Case presentation

MRI conducted to examine the orthopedic disease of the patients, a 49-year-old Japanese woman, also identified a tumor in her pelvis. A CT scan revealed a tumor mass on the right side of the pelvic floor and clear nutrient vessels originating from the splenic and celiac arteries. An omental primary tumor or accessory spleen was thus suspected, and tumor resection was performed. The tumor was a light brown solid tumor with a smooth margin, measuring 5.2 × 3.8 × 3.5 cm. Histopathologically, the tumor was composed mainly of spindle and epithelioid cells, and large and small blood vessel formation was observed. In the immunohistochemical staining, tumor cells were positive for human melanin black 45 (HMB-45) and Melan-A and partially positive for alpha-smooth muscle actin. The final diagnosis was PEComa of the greater omentum.

Conclusions

Although omental PEComa is very rare, it should be considered as a differential disease of an omental primary tumor.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 2. The 2nd Decade: From the Radiologic Pathology Archives

Malignant renal tumors account for 7% of childhood cancers, and Wilms tumors are by far the most common-but not in older children and adolescents. Among individuals in the latter half of their 2nd decade of life, renal cell carcinoma (RCC) is more common than Wilms tumor. The histopathologic spectrum of RCCs in children differs from that in adults. The most common subtype of RCC in children and adolescents is Xp11.2 translocation RCC, which is distinguished by hyperattenuation at nonenhanced computed tomography, a defined capsule, and associated retroperitoneal lymphadenopathy. Papillary RCC is the second most common histologic subtype. It enhances less intensely compared with the adjacent renal parenchyma and has a propensity for calcification. Clear cell RCC is seen in patients with von Hippel-Lindau disease and is distinguished by its relatively hypervascular nature. Medullary carcinoma affects adolescents with the sickle cell trait and is characterized by an infiltrative growth pattern and extensive metastasis at presentation. Angiomyolipoma is seen in children with tuberous sclerosis complex and is often multifocal and hypervascular, with macroscopic fat. Metanephric tumors are central, circumscribed, and typically calcified. Lymphoma usually manifests as multifocal masses, but it may involve a solitary mass or infiltrative pattern. Extensive adenopathy and involvement of the gastrointestinal tract or other organs also may be seen. Primitive neuroectodermal tumor is an aggressive neoplasm that is typically quite large at diagnosis. Knowledge of the clinical, biologic, and histopathologic features of renal tumors in older children and adolescents and their effects on the imaging appearance can help the radiologist offer a useful preoperative differential diagnosis.

Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation

OBJECTIVE

This article describes, illustrates, and correlates imaging and pathologic features of primary vascular mesenchymal neoplasms of the liver, which arise from the vascular endothelium and perivascular epithelioid cells.

CONCLUSION

Familiarity with the spectrum of benign, malignant-potential and malignant vascular neoplasms, and nonneoplastic mimickers allows consideration in the differential diagnosis of enhancing hepatic masses. Understanding relevant pathologic features facilitates recognition of key imaging features, specifically dynamic contrast enhancement patterns on CT and MRI, which provide a useful classification system.

Liver Perivascular Epithelioid Cell Tumor with an Unusual Location: Diagnostic Characteristics with Multidetector Computed Tomography and Magnetic Resonance Imaging

Primary perivascular epithelioid cell tumor (PEComa) of the liver is a very rare tumor that originates from mesenchyma. Gastrointestinal tract with perivascular distribution is the most common anatomic sites of these tumors. Only few cases of hepatic PEComa have been described so far. Malignant PEComas exhibit aggressive behavior with poor prognosis, making early diagnosis crucial. Hereby, we report a 79-year-old female with unusually located mass in the liver. A partial curative hepatectomy has been done, and PEComa was diagnosed histopathologically. No evidence of recurrence was observed during the 6-month follow-up.

Pneumothorax caused by cystic and nodular lung metastases from a malignant uterine perivascular epithelioid cell tumor (PEComa)

Perivascular epithelioid cell tumors (PEComas) are mesenchymal neoplasms with immunoreactivity for both melanocytic and smooth muscle markers. PEComas occur at multiple sites, and malignant PEComas can undergo metastasis, recurrence and aggressive clinical courses. Although the lung is a common metastatic site of PEComas, they usually appear as multiple nodules but rarely become cystic or cavitary. Here, we describe a female patient whose lungs manifested multiple cystic, cavity-like and nodular metastases 3 years after the resection of uterine tumors tentatively diagnosed as epithelioid smooth muscle tumors with uncertain malignant potential. This patient's subsequent pneumothorax necessitated video-assisted thoracoscopic surgery, and examination of her resected lung specimens eventually led to correcting the diagnosis, i.e., to a PEComa harboring tuberous sclerosis complex 1 (TSC1) loss-of-heterozygosity that originated in the uterus and then metastasized to the lungs. The administration of a gonadotropin-releasing hormone analogue later stabilized her clinical course. To the best of our knowledge, the present case is the first in the literature that associates PEComas with a TSC1 abnormality. Additionally, the pulmonary manifestations, including imaging appearance and pneumothorax, somewhat resembled those of lymphangioleiomyomatosis, a representative disease belonging to the PEComa family. Although PEComas are rare, clinicians, radiologists and pathologists should become aware of this disease entity, especially in the combined clinical setting of multiple cystic, cavity-like, nodular lesions on computed tomography of the chest and a past history of the tumor in the female reproductive system.

Hepatic perivascular epithelioid cell tumor treated by transarterial embolization plus radiofrequency ablation: A case report and literature review

BACKGROUND

Perivascular epithelioid cell tumors (PEComas) are extremely rare mesenchymal entities with potentially malignant properties; the liver cases are not encountered frequently. Owing to themalignant potential, these tumors are treated by surgical methods to ensure total resection. In the present report, a case of liver PEComa treated by embolization combined with radiofrequency ablation (RFA) has been described.

CASE SUMMARY

A 40-year-old female was admitted for the detection of a liver mass during an annual physical examination. The patient did not have any liver disease background, enhanced computed tomography (CT), and magnetic resonance revealed a huge mass in the right lobe. Pathology gave the diagnosis of PEComa, for disagreement of open surgery, a combination of transarterial embolization (TAE) and RFA were applied for treatment and the outcomes were acceptable, the patient was under follow-up to observe the long-term effect.

CONCLUSION

Interventional procedures such as TAE and RFA are feasible and effective for such lesions and may serve as an alternate when resection is not indicated. Prospective studies are warranted to verify the long-term outcomes.

Primary perivascular epithelioid cell tumors of the liver: CT/MRI findings and clinical outcomes

OBJECTIVES

The purpose of our study was to describe the CT and MRI features of primary PEComas of the liver and to document the associated clinical outcomes.

METHODS

Retrospective study included 20 patients with primary hepatic perivascular epithelioid cell tumors (PEComa) with pathology and clinical outcomes for correlation.

RESULTS

Study group included 20 patients: 16 women, 4 men; mean age 53 (range 35-77) years. Initial pathology diagnoses were classic angiomyolipoma (AML) (n = 11), epithelioid AML (n = 7), and PEComa not otherwise specified (n = 2). Mean tumor size was 5.1 (range 1.3-15.0) cm. CT/MRI features included well-defined margins 20/20 (100%), arterial enhancement 18/19 (95%), subcapsular location 17/20 (85%), heterogeneous 16/20 (80%), dysmorphic vessels 14/20 (70%), fat 13/20 (65%), hemorrhage 4/20 (20%), cystic components 4/20 (20%), and calcification 1/20 (5%). At the time of discovery, 18 patients were asymptomatic and their tumors were incidentally detected on imaging, and 2 patients were symptomatic. Ultimately, 18 tumors were benign and 2 developed metastases.

CONCLUSIONS

On CT/MRI, most primary hepatic PEComas were well-defined, arterial enhancing, subcapsular, heterogeneous masses that often had dysmorphic vessels and contained fat. Most tumors were benign but complications included local symptoms, bleeding, and malignant change.

Renal Epithelioid Angiomyolipoma Associated with Pulmonary Lymphangioleiomyomatosis: Imaging Findings

Renal angiomyolipomas (AMLs) and pulmonary lymphangioleiomyomatosis (LAM) are the most common tumors of the perivascular epithelioid cell (PEComa) family. Both may be associated with tuberous sclerosis (TS) complex. Epithelioid AML (EAML) is a rare variety of AMLs, with a potential aggressive behavior. There are few reports in the English literature addressing on the imaging findings of renal EAMLs, which are considered nonspecific. We present the sonographic, computed tomographic, and magnetic resonance imaging findings of a renal EAML in a pregnant woman with concomitant pulmonary lesions indicative of LAM, without stigmata of TS. We conclude the importance of considering EAML as a possible diagnosis in the presence of a large renal mass with high cellular content and small amounts of fat in the coexistence of pulmonary LAM.

Two cases of perivascular epithelioid cell tumor of the uterus: clinical, radiological and pathological diagnostic challenge

Background

Perivascular epithelioid cell tumor (PEComa) is a rare subtype of mesenchymal origin tumor composed of epithelioid cells which exhibits immunohistochemical co-expressions of melanocytic markers and smooth muscle markers.

Case presentation

In the first case, malignant uterine PEComa with vaginal and multiple lung metastasis was misdiagnosed preoperatively as uterine leiomyosarcoma despite a preoperative punch biopsy and immunohistochemical analysis of the metastatic vaginal mass. In the second case, synchronous uterine PEComa showing benign histology with lymph node involvement was incidentally detected after a staging operation for ovarian cancer. Definitive diagnosis of uterine PEComa was achieved only after hysterectomy despite preoperative assessment with pelvic magnetic resonance imaging and punch biopsy of metastatic lesion.

Conclusion

The authors report two rare cases of uterine PEComa diagnosed postoperatively based on the morphologic and immunohistochemical features.

Current Concepts in Non-Gastrointestinal Stromal Tumor Soft Tissue Sarcomas: A Primer for Radiologists

Non-gastrointestinal stromal tumor (GIST) soft tissue sarcomas (STSs) are a heterogeneous group of neoplasms whose classification and management continues to evolve with better understanding of their biologic behavior. The 2013 World Health Organization (WHO) has revised their classification based on new immunohistochemical and cytogenetic data. In this article, we will provide a brief overview of the revised WHO classification of soft tissue tumors, discuss in detail the radiology and management of the two most common adult non-GIST STS, namely liposarcoma and leiomyosarcoma, and review some of the emerging histology-driven targeted therapies in non-GIST STS, focusing on the role of the radiologist.