Perivascular epithelioid cell tumor

Hepatic perivascular epithelioid cell tumor: a retrospective analysis of 36 cases

Background and aims

Hepatic perivascular epithelioid cell tumor (PEComa) is a rare type of mesenchymal neoplasm and lacks systematic reports. The aim was to analyze the features of hepatic PEComa in order to provide our own experience for diagnosis and management from a single center.

Methods

We retrospectively analyzed clinical data, imaging findings, pathology, treatments and prognosis of 36 patients with hepatic PEComa in the First Affiliated Hospital of Zhengzhou University from January 2016 to September 2023.

Results

29 females and 7 males (median age, 47.8 years) were included in this study. The majority (26/36, 72.2%) of patients were diagnosed incidentally with non-specific symptoms. Abnormal enhancement of enlarged blood vessels (27/36,75%) can be observed on CT/MRI and only 7 patients (19.4%) were correctly diagnosed by imaging examinations. The positive immunohistochemical expressions were HMB-45(35/36,97.2%), Melan-A (34/35,97.1%), SMA (23/26,88.5%) and CD34(86.7%,26/30). Treatments include resection (24/36,67.7%), radiofrequency ablation (6/36,16.7%), transcatheter arterial chemoembolization(1/36,2.7%), conservative clinical follow-up(2/36,5.6%), and sirolimus-chemotherapy (3/36,8.3%). During the follow-up period (range, 2-81 months), except for one patient with a single intrahepatic recurrence and 3 malignant patients died in 6 months, the remaining patients had no signs of recurrence and metastasis.

Conclusions

Hepatic PEComa has no specific clinical features and mainly depends on clinicopathological characteristics for accurate diagnosis. Resection is the best treatment for benign PEComa, but TACE and radiofrequency ablation can also be considered in case of contraindications for surgery.

Perivascular epithelioid cell tumor of the lacrimal gland

A 33-year-old lady was referred to our clinic with a history of left upper eyelid swelling and difficulty to open her left eye for more than 4 years. Her globe was in infero-nasal displacement, and ocular movement was not full, with restriction to every direction. No clinical sign including eye redness, pain or visual loss was found on examination. Exophthalmometry confirmed 2 mm of left-sided proptosis. Computed tomography (CT) imaging of the orbit obtained in axial and coronal planes depicted an irregular and heterogeneous soft-tissue density mass in the left lacrimal gland, measuring 25 × 17 mm. Magnetic resonance imaging (MRI) revealed the mass of slightly longer T1 and slightly longer/shorter T2 signal, and Gd-enhanced MRI showed a significant enhancement. The tumor was first presumably diagnosed of pleomorphic adenomas. A surgery was applied to remove the tumor completely. Histopathological evaluation led to the diagnosis of PEComa.

Clinicopathological features of primary malignant perivascular epithelioid cell tumors of ureter: Histologic-radiologic correlation

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor that is mainly seen in middle-aged women. PEComa originating in the ureter is extremely rare it is unclear whether they display typical clinical and radiographic features seen elsewhere. Herein, we report findings from 2 cases of primary PEComa of the ureter that we classified as malignant. Case 1: A 45-year-old woman was admitted to the hospital with intermittent distension in her waist. After appropriate imaging, the right ureter and right kidney were excised under general anesthesia. The tumor measured 1.4 cm. Microscopically, the tumor displayed infiltrative growth, >2 mitoses per 10 high power fields (HPF), necrosis, and lympho-vascular invasion. Case 2: A 30-year-old woman was admitted to the hospital due to hematuria 20 days duration. The left ureter and left kidney were ultimately excised under general anesthesia. The tumor measured 2 cm. Microscopically, the tumor showed infiltrative growth and >2 mitoses/10 HPF. Our cases were diagnosed as malignant PEComa. No disease recurrence was observed in either of the two patients during the postoperative follow-up period. Malignant primary ureteral PEComa is very rare. The clinical manifestations are not specific, and it is usually misdiagnosed as a malignant neoplasm on imaging. Therefore, its diagnosis requires pathological examination and immunohistochemical analysis of the sampled or resected tumor. Treatment requires a complete surgical resection and regular clinical follow-up.

Treatment of malignant perivascular epithelioid cell tumor (PEComa) on the knee with an anterolateral thigh free flap: A case report

RATIONALE

The World Health Organization defines a perivascular epithelioid cell tumor (PEComa) as a mesenchymal neoplasia composed of perivascular epithelioid cells with characteristic morphological and immunohistochemical features. Although PEComas have the potential to behave in a malignant fashion, malignant PEComas are extremely rare.

PATIENT CONCERNS

An 83-year-old man visited our clinic presented with palpable, painless, and movable mass in the right knee area.

DIAGNOSES

Malignant PEComa was diagnosed by incisional biopsy. No metastases was confirmed by radiologic imaging including PET/CT, magnetic resonance imaging, high resolution computed tomography.

INTERVENTIONS

We performed wide excision of the mass and used an anterolateral thigh free flap to reconstruct the defect on the right knee.

OUTCOMES

The permanent histopathology showed malignant PEComa was totally resected. The flap which was performed to cover the defect was survived and the patient discharge without any complications.

LESSONS

PEComa can metastasize to various anatomical regions. Although there is no established standardized treatment, radical resection is still considered the cornerstone of treatment. Rapid and appropriate defect coverage is important to improve the patient's prognosis.

Management Strategies for Adults with Locally Advanced, Unresectable or Metastatic Malignant Perivascular Epithelioid Cell Tumor (PEComa): Challenges and Solutions

PEComa (PEC tumor; perivascular epithelioid cell tumors) is a rare group of tumors of mesenchymal origin composed of perivascular epithelioid cells (PEC) with features of melanotic and smooth muscle differentiation. In this article, we would like to present the current treatment options for this group of tumors. PEComas are classified as tumors of uncertain malignant potential because recurrences occur after radical treatment. The primary treatment is surgical resection with negative margins. Due to the different locations of the tumors, often the cooperation of multispecialty surgeons is required during the operations. In locally advanced cases, cytoreduction and HIPEC may be effective but still are an experimental treatment. For nonresectable PEComa chemotherapy, mTOR inhibitors and VEGFR inhibitors are used.

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.

Hepatic epithelioid angiomyolipoma: magnetic resonance imaging characteristics

PURPOSE

The aim of the study was to analyze MR imaging features of hepatic epithelioid angiomyolipoma (HEAML).

METHODS

This study included 113 patients with 122 pathologically confirmed HEAML who underwent enhanced MRI scanning before partial hepatectomy. MR images were retrospectively reviewed and correlated with pathological findings.

RESULTS

The mean age of 113 patients was 48.12 ± 11.77 years old, and the male to female ratio was 1:3.35 with 87 females (76.99%). 107 (94.69%) patients presented as single tumor, and 96 patients (84.96%) were asymptomatic. 122 HEAML lesions were diagnosed pathologically in 113 patients, with the average of 4.47 ± 3.26 cm. 109 lesions (89.34%) and 108 lesions (88.52%) showed regular and well-defined boundary. On T1WI, 121 lesions (99.18%) mainly presented hypointensity. On T2WI, 118 lesions (96.72%) and 109 lesions (89.34%) mainly showed hyperintensity and heterogeneous signals. Most of the lesions (97.46%) showed hyperintensity on DWI. 118 lesions (96.72%) manifested as severe hyperenhancement and 106 lesions (86.89%) showed heterogeneity during the arterial phase. As for the lesion enhancement pattern, 73 lesions (59.84%) presented as persistent enhancement, 37 lesions (30.33%) as wash out, 8 lesions (6.56%) as degressive enhancement, and 4 lesions (3.28%) as poor blood supply. Additionally, 96 lesions (78.69%) with intra-tumor vessels and 85 lesions (69.67%) with outer rim were confirmed during the delayed phase.

CONCLUSION

At enhanced MRI, hypointensity on T1WI, hyperintensity and heterogeneous signals on T2WI, hyperintensity on DWI, little or no fat component, heterogenous hyperenhancement, persistent enhancement, intra-tumor vessels, and outer rim would be helpful to diagnose HEAML.

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.

Case Report: Perivascular epithelioid tumors of the gastrointestinal tract

Background

Perivascular epithelioid cell tumor of the gastrointestinal tract (GI PEComa) is a rare mesenchymal neoplasm. GI PEComa is mostly observed in the colon and has a marked middle-aged female predominance. PEComa has no typical clinical or imaging manifestations or endoscopic characteristics. Therefore, the diagnosis of this disease mostly relies on pathological findings. HMB-45 is a sensitive immune marker of PEComa.

Case presentation

We reported a case of a middle-aged female with sigmoid colon PEComa. To exclude carcinogenesis, the large basal polyp in the sigmoid colon was removed by endoscopic mucosal resection (EMR). Immunohistochemistry analysis results showed that this lesion expressed HMB-45, which is a characteristic melanin marker of PEComa. Finally, the lesion was diagnosed as sigmoid colon PEComa. At the time of submission of this report, surgical resection was the primary treatment for PEComa. Though the characteristics of tumor biology and clinical behavior in PEComa are not clear, the boundary is clear, and the tumor can be completely removed. However, close follow-up is required after the surgery because of the lesion's undetermined benign and malignant nature.

Conclusion

The present case study emphasizes the importance of pathological diagnosis. Therefore, upon finding gastrointestinal polyps with a mucosal ulcer under endoscopy, the GI PEComa diagnosis should be considered. It is necessary to detect the characteristic melanin markers of PEComa. Due to the rarity of these cases, challenges are faced in diagnosing and treating PEComa.

♣Evaluation of clinicopathological profiles and development of a risk model in renal epithelioid angiomyolipoma patients: a large-scale retrospective cohort study

BACKGROUND

To identify the malignant potential and prognostic indicators of renal epithelioid angiomyolipoma (eAML), clinicopathological and molecular features as well as the drug efficacy of 67 eAML cases were analyzed.

MATERIALS AND METHODS

Sixty-seven renal eAML patients were enrolled and the immunohistochemical features of these patients were examined. FFPE slides of all patients were re-examined. 21 patients with metastasis received Everolimus 10 mg orally once daily. Responses were evaluated with RECIST criteria by three authors. A risk stratification model was constructed using the following factors: pT3 and pT4, presence of necrosis, mitotic count ≥ 2; the presence of atypical mitoses; severe nuclear atypia, SMA negative, Ki-67 ≥ 10%.

RESULTS

The average percentage of the epithelioid component was 85.6% (range 80-95%). Immunohistochemically, Ki-67 ≥ 10% and negative SMA staining were significantly correlated with malignant characteristics (Ki-67: p < 0.001; SMA: p = 0.001). Survival analysis suggested that pT3-pT4 stage, presence of necrosis, severe nuclear atypia, presence of atypical mitoses, mitotic count ≥ 2, Ki-67 ≥ 10% and negative SMA expression were significantly associated with poorer PFS and OS (p < 0.05). The risk model sufficiently discriminated recurrence/metastasis (AUC = 0.897) and cancer-specific mortality (AUC = 0.932) of renal eAML patients in different risk groups. 21 patients had received Everolimus targeted therapy after recurrence/metastasis. The best response for Everolimus treatment was 8/21 (38.1%) partial responses (PR), 9/21 (42.9%) stable disease (SD) and 4/21 (19.0%) progressive disease (PD).

CONCLUSION

The risk stratification model could well distinguish eAML patients at high risk of recurrence/metastasis. Everolimus targeted treatment showed good efficacy in patients with recurrence/metastasis.

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.

Uterine perivascular epithelioid tumors (PEComas) with lung metastasis showed good responses to mTOR and VEGFR inhibitors: A case report

Perivascular epithelioid cell tumors (PEComas) are extremely rare mesenchymal neoplasms for which the uterus is the most common site. The prognosis of malignant PEComa is poor as it is characterized by resistance to classical chemotherapies. Both mTOR inhibitors and VEGFR inhibitors exhibited clinical utility in treating malignant PEComas, but the combination of these two regimens has rarely been reported. In the present case, a uterine PEComa patient developed lung and bone metastases after the failure of chemotherapies and derived benefit from the combination regimen of an mTOR inhibitor (everolimus) and a VEGFR inhibitor (apatinib), achieving a 15-month progression-free survival. Targeted NGS revealed TP53 and TSC2 mutations in the patient’s primary uterine tumors and plasma ctDNA at disease progression. Plasma ctDNA clearance was consistent with a radiologic partial response determined by RECIST 1.1 and a reduction of neuron-specific enolase (NSE) and cancer antigen 125 (CA125) levels. Thus, we provided clinical evidence supporting the administration of combined therapy of mTOR and VEGFR inhibitors to metastatic uterine PEComa patients and highlighted the application of serial plasma ctDNA profiling for dynamic disease monitoring.

A Rare Case of a Translocation-Associated Perivascular Epithelioid Cell Neoplasm (PEComa)

A perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm composed of perivascular epithelioid cells with distinctive histologic, immunohistochemical, and genetic features. PEComas arising from various anatomical sites have been reported, but gastrointestinal PEComas are extremely rare entities. Here, we discuss the clinical and pathological features of a gastrointestinal PEComa with a transcription factor E3 (TFE3) translocation in a 17-year old adolescent male with a clinical presentation of abdominal pain and gastrointestinal bleeding. Our case report provides insight into this rare entity as well as discusses the pathophysiological aspects of TFE3-SFPQ-associated GI PEComas and their management.

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.

Perivascular epithelioid cell tumour (PEComa): an unusual cause of painful defaecation

Perivascular epithelioid cell tumours (PEComa) are rare tumours of mesenchymal origin. We report a 39-year-old patient who presented with painful defecation secondary to an anorectal mass. The diagnosis of anorectal PEComa was confirmed following excision and histopathological examination. We review the literature and discuss the management of this uncommon entity.

PNL2: A Useful Adjunct Biomarker to HMB45 in the Diagnosis of Uterine Perivascular Epithelioid Cell Tumor (PEComa)

Perivascular epithelioid cell tumors (PEComa) are rare neoplasms characterized by co-expression of melanocytic and muscle markers. HMB45 and Melan-A are used to confirm a PEComa diagnosis; however, both are often focally expressed and sensitivity for Melan-A is low. PNL2 is a reliable biomarker for epithelioid melanoma and renal angiomyolipoma/PEComa. The objective of this study was to determine PNL2 utility in diagnosing uterine PEComas as well as distinguishing PEComas from uterine smooth muscle tumors (SMTs). Twenty-one uterine PEComas and 45 SMTs were analyzed for PNL2; a subset was also stained for HMB45, Melan-A, Cathepsin-K, Desmin, and h-Caldesmon. Cases were scored as negative (0), focal (<10% of tumor cells), or patchy to diffusely positive (>10% of tumor cells). PEComas were positive for PNL2, HMB45, and Melan-A in 86%, 100%, and 57% of cases, respectively. In PEComas, PNL2 was patchy to diffusely positive more frequently (10/18, 56%) than Melan-A (4/12, 33%). In contrast, 2 of 45 (4%) SMTs were focally PNL2 positive; HMB45 was focally positive in 4 SMTs (11%) and all were negative for Melan-A. Desmin and h-Caldesmon were positive in 90% and 57% of PEComas, and 91% and 82% of SMTs. Cathepsin-K was positive in 100% of PEComas and 93% of SMTs. PNL2 is a useful biomarker for the diagnosis of uterine PEComa, with comparable sensitivity and specificity to HMB45. In contrast, PNL2 stains more PEComas when compared with Melan-A. Cathepsin-K, Desmin, and h-Caldesmon are of little utility for distinguishing PEComas and SMTs; however, lack of Cathepsin-K argues against PEComa. These results suggest that PNL2 should be used in conjunction with HMB45 in the diagnosis of PEComa of the uterine corpus.

Unusual Primary Neoplasms of the Adult Liver: Review of Imaging Appearances and Differential Diagnosis

The radiological appearance of common primary hepatic tumors such as hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) is widely recognized. Hepatic masses with unusual histology are occasionally encountered, but seldom suspected on imaging. However, many possess characteristic imaging findings, which when assessed along with the clinical and demographic background and serum tumor markers, may enable a prospective diagnosis. This review attempts to familiarize the reader with the clinicopathological characteristics, imaging manifestations, and differential diagnosis of these unusual liver tumors in adults. Biphenotypic primary liver carcinoma is suspected in masses showing distinct areas of HCC and CCA-type enhancement pattern in cirrhotic livers. Fibrolamellar carcinoma occurs in young individuals without underlying chronic liver disease and shows a characteristic T2-hypointense scar frequently showing calcification. Perivascular epithelioid cell tumors are differentials for any arterial hyperenhancing mass in the noncirrhotic liver, particularly in patients with tuberous sclerosis. Multifocal subcapsular tumors showing target-like morphology, capsular retraction and "lollipop" sign are suspicious for epithelioid hemangioendothelioma. On the other hand, multiple hemorrhagic lesions showing patchy areas of bizarre-shaped arterial phase hyperenhancement are suspicious for angiosarcoma. Primary hepatic lymphoma (PHL) is suspected when patients with immunosuppression present with solitary or multifocal masses that insinuate around vessels and bile ducts without causing luminal narrowing. Intense diffusion restriction and low-level homogeneous or target-like enhancement are also ancillary features of PHL. Primary hepatic neuroendocrine tumor shows uptake on Ga-68 DOTANOC PET/CT. Although a straightforward diagnosis may be difficult in these cases, awareness of the characteristic imaging appearances is helpful in suspecting the diagnosis.

A Curious Case of Colonic Perivascular Epithelioid Cell Tumor: A Unique Diagnosis With Variable Presentations

A 67-year-old female with a history of colon cancer underwent colonoscopy. An 8 mm semi-pedunculated, friable, and ulcerated lesion of the ascending colon was removed completely using a hot snare. Immunohistochemical staining showed strong positivity for transcription factor binding to IGHM enhancer 3 (TFE-3) and was partially positive for Human Melanoma Black (HMB-45), consistent with a diagnosis of perivascular epithelioid cell tumor (PEComa). The patient underwent endoscopic submucosal dissection of the residual lesion in the ascending colon without complications. Here, we discuss the clinical and histopathologic characterizations that helped guide the diagnosis and management of this exceedingly rare entity.

Malignant Epithelioid Neoplasm of the Brain

Malignant epithelioid tumors have been described in various organ systems, but are rarely seen in the brain. They are aggressive tumors and have high mortality. In certain cases, the immunohistochemistry (IHC) findings may not be sufficient to clarify the diagnosis. In these cases, next-generation genetic sequencing may play a role in clarifying the diagnosis. In addition to lab testing, a thorough history and physical exam are necessary to rule out other sources of the tumor such as melanoma. Patients presenting with neurological symptoms are cared for by a wide variety of physicians, hence it is important to raise awareness of rare tumors in order to provide timely and appropriate management and referral for these patients. We present the case of a middle-aged woman who was diagnosed with a ‘malignant epithelioid neoplasm’ of the brain, a rare variety of tumors. We also give the clinical course of this illness.

Malignant perivascular epithelioid tumor of the vagina: Report of a rare case with brief review of literature

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors with immunohistochemical co-expression of melanocytic and myoid markers. Vaginal PEComas have been described in only nine cases so far. We describe the case of a 65-year-old female with a large growth in the left lateral vaginal wall. Biopsy imprint smears showed dispersed tumor cells with anisonucleosis, multinucleation, and bizarre forms, suggestive of a malignant tumor. Histopathology, however, showed perivascular arrangement of clear epithelioid cells, focal necrosis, intracellular brown pigment in few cells, and mitotic activity at 2 to 3 per 50 high power fields. Immunohistochemical positivity for vimentin, HMB-45, S-100 protein, desmin, and MyoD1 assisted in rendering a final pathological diagnosis of malignant PEComa of the vagina. Further work-up revealed metastatic deposits in liver and retroperitoneal lymph nodes. PEComa arising in vagina is an unusual phenomenon with the malignant variant being an extremely rare tumor. Awareness of the characteristic morphology and utilization of a panel of immunohistochemical stains are mandatory to be able to make a precise diagnosis and appropriate prognostication.

[Malignant renal epithelioid angiomyolipoma (EAML): about a rare case]

L’angiomyolipome rénal épithélioïde malin (AREM) est une entité pathologique rare longtemps considérée comme lésion hamartomateuse et dont le diagnostic positif est purement immuno-histochimique, microscopiquement, il se caractérise par des cellules mononuclées épithélioïdes a cytoplasme clair présentant des atypies cytonucléaires sévères, et exprimant les marqueurs musculaires lisses et mélanocytaires (HMB 45). Nous rapportons un cas rare d’AREM diagnostiqué après analyse anatomopathologique d’une tumeur retropéritonéale dont l’origine ne pourrait être précisée préalablement par la tomodensitométrie.

Pericytes in Sarcomas and Other Mesenchymal Tumors

Tumors of mesenchymal origin are a diverse group, with >130 distinct entities currently recognized by the World Health Organization. A subset of mesenchymal tumors grow or invade in a perivascular fashion, and their potential relationship to pericytes is a matter of ongoing interest. In fact, multiple intersections exist between pericytes and tumors of mesenchymal origin. First, pericytes are the likely cell of origin for a group of mesenchymal tumors with a common perivascular growth pattern. These primarily benign tumors grow in a perivascular fashion and diffusely express canonical pericyte markers such as CD146, smooth muscle actin (SMA), platelet-derived growth factor receptor beta (PDGFR-β), and RGS5. These benign tumors include glomus tumor, myopericytoma, angioleiomyoma, and myofibroma. Second and as suggested by animal models, pericytes may give rise to malignant sarcomas. This is not a suggestion that all sarcomas within a certain subtype arise from pericytes, but that genetic modifications within a pericyte cell type may give rise to sarcomas. Third, mesenchymal tumors that are likely not a pericyte derivative co-opt pericyte markers in certain contexts. These include the PEComa family of tumors and liposarcoma. Fourth and finally, as "guardians" that enwrap the microvasculature, nonneoplastic pericytes may be important in sarcoma disease progression.

Comparison of MRI Features of Epithelioid Hepatic Angiomyolipoma and Hepatocellular Carcinoma: Imaging Data From Two Centers

Introduction: Epithelioid hepatic angiomyolipoma (Epi-HAML) can easily be misdiagnosed as a malignant tumor such as hepatocellular carcinoma (HCC) because of the low-fat content on imaging. We analyzed and compared the magnetic resonance imaging (MRI) features of Epi-HAML and HCC, which would aid in disease diagnosis.

Methods: We included 30 pathologically confirmed patients with Epi-HAML and 80 with HCC, who underwent both MRI unenhanced scan and three-phase contrast-enhanced MRI scan. The clinical and MRI features of the two groups were summarized and analyzed.

Results: Epi-HAML showed significant differences compared to HCC group in terms of clinical features such as sex preference, age, concomitant diseases (hepatitis B and cirrhosis), and elevated plasma alpha-fetoprotein (AFP) (P < 0.001). In addition, there were statistically significant differences between both tumor types with regard to conventional MRI findings such as a solitary tumor (100 vs. 83.8%, P = 0.018), well-defined (93.3 vs. 71.3%, P = 0.027), mild hyperintensity (40.0 vs. 3.7%, P < 0.001) on DWI with high b-value, fat within the tumor (43.3 vs. 8.8%, P < 0.001), and rare necrosis (3.3 vs. 26.3%, P = 0.016). Besides, Epi-HAML displayed significant differences compared to HCC in terms of contrast-enhanced MRI characteristics such as draining hepatic vein (30.0 vs. 3.8%, P < 0.001), portal vein tumor thrombus (0 vs. 13.8%, P = 0.033), hypointensity at delayed phase (70.0 vs. 95%, P = 0.001), intra-tumor vessel at delayed phase (36.7 vs. 10.0%, P = 0.003), pseudocapsule (20.0 vs. 78.8%, P < 0.001), and prolonged enhancement (56.7 vs. 1.2%, P < 0.001).

Conclusion: Epi-HAML frequently occurs in middle-aged women and usually lacks characteristic clinical symptoms. Typically, Epi-HAML presents as an isolated and well-defined tumor with rich vasculature. Specific MRI features such as intra-tumor fat, intra-tumor vessel, draining hepatic vein, prolonged enhancement, and lack of capsule may contribute to a more confident diagnosis of Epi-HAML.

Does epithelioid angiomyolipoma have poorer prognosis, compared with classic angiomyolipoma?

Purpose

Classic angiomyolipoma (AML) is common benign kidney tumor. However, some studies have claimed that epithelioid angiomyolipoma (EAML) has malignant potential. We compared the patient characteristics and prognosis of EAML and classic AML to demonstrate predicting factors and poorer prognosis of EAML.

Materials and Methods

The medical records of 231 patients who were diagnosed with EAML (n=27, 11.7%) or classic AML (n=204, 88.3%), were reviewed. All patients underwent computed tomography (CT) scans before operation or needle biopsy. We assessed the age, sex, tumor size, body mass index, comorbidities, and Hounsfield unit (HU) according to each CT phase. We defined the unfavorable group as patients with recurrence, metastasis and death due to tumor progression. Logistic regression analysis was used to predict EAML.

Results

EAML patients were younger (41.2 years vs. 49.1 years, p=0.001), predominantly male (55.6% vs. 28.4%, p=0.005), and had a larger tumor (7.5 cm vs. 4.2 cm, p<0.001). The median pre-contrast HU was not significantly different between EAML and classic AML (29.9±23.7 vs. 14.7±41.0, p=0.071). In multivariable analysis, younger age (odds ratio [OR], 0.96; p=0.032), male sex (OR, 3.33; p=0.013), and tumor larger than 4 cm (OR, 3.8; p=0.009) were significant predictive factors. Five patients (18.5%) had unfavorable outcomes, two patients had lymph node metastasis, and three patients had lung metastasis.

Conclusions

Patient and tumor characteristics can be helpful in determining the type of AML preoperatively. Younger age, male sex, and larger tumor mass may increase the possibility of diagnosing EAML. EAML has malignant potential and requires careful follow-up.

Successful management of perivascular epithelioid cell tumor of the rectum with recurrent liver metastases: A case report

RATIONALE

The perivascular epithelioid cell tumor (PEComa) is rare in young man and rarely occurs in the large intestine.

PATIENT CONCERNS

The clinical characteristics, diagnosis, and managements in a 28-year-old boy who presented with sudden onset of cramping and abdominal pain and intermittent melena with a blood pressure of 74/39 mm Hg was retrospectively reviewed. CT scan of the abdomen revealed a 8.9 × 7.2 cm mass in the pelvic floor.

DIAGNOSES

Given the difficulty of obtaining a diagnostic specimen, surgical resection was performed. The pathology report of lower anterior resection was malignant PEComa of the rectum in 2006.

INTERVENTIONS

Treatment consisted of surgical resection only without additional adjuvant therapy. Over the next 49 months (until 2010) after surgery, abdominal CT showed a 0.6-cm hypodense mass over the liver with suspected liver metastasis. He refused any further evaluation and treatment. After 4 years (2014), abdominal CT showed that the original mass had increased from 0.6 to 1.5 cm and the number of tumors had increased from 1 to 3. In August 2014, he underwent a metastatic hepatectomy without additional chemotherapy or radiotherapy.

OUTCOMES

We noted that the metastatic progression was slow in the 4 years after the first operation. At 28 months after metastatic hepatectomy, the patient was doing well. There was also no recurrence of the PEComa of the rectum at the 120-month follow-up in 2016.

LESSONS

To the best of our knowledge, this is the first report of a PEComa of the rectum with liver metastases treated with only surgical resection. At approximately 8.8 cm, this is the largest PEComa of the rectum reported in the recent literature.

An Inguinal Perivascular Epithelioid Cell Tumor Metastatic to the Orbit

Malignant PEComas are rare mesenchymal neoplasms. These tumors harbor distinct myomelanocytic phenotype. The PEComa family of tumors includes lymphangioleiomyomatosis, angiomyolipoma, clear cell sugar tumor of the lung, and myomelanocytic tumor of the falciparum ligament/ligamentum teres. PEComas have no known normal cell counterpart. Majority of PEComas are benign and occur predominantly in the middle-age women. These tumors are commonly encountered in the uterus. Herein, we report a 20-year-old woman with a left inguinal mass metastatic to orbit, brain, lumbar spine, and skin at presentation. To our knowledge, this is the first case of metastatic PEComa to the orbit. This is the third case of primary PEComa of the inguinal area.

Primary pancreatic perivascular epithelioid cell tumor (PEComa): A surgical enigma. A systematic review of the literature

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor, with distinctive morphology and expression of myo-melanocytic markers. Current scientific literature reported just 24 cases of pancreatic PEComas. With our systematic review, we aimed at improving our understanding of the disease, focusing on the knowledge gained on epidemiology, etiology, clinical presentation, diagnosis, treatment and prognosis.

METHODS

Based on the PRISMA guidelines, a systematic research was carried out on PubMed/MEDLINE, Web of Science, Scopus, EMBASE, and EBSCO using the search terms: ("perivascular epithelioid cell tumor" OR ″PEComa") and ("pancreas "OR″ pancreatic").

RESULTS

The 4th-6th decades of life and female sex (86.9%) turned out as the most affected. Pancreatic head was the most involved site (50%), with a single lesion in almost all cases. The diagnosis was only obtained after histopathological examination (70.8%). The clinical presentation was non-specific, abdominal pain being the main symptom (60.9%). At immunohistochemistry, PEComa showed benign epithelioid predominance and a strong positivity for HMB-45, Melan-A, and α-SMA. Surgical resection was performed in almost all cases, while for one patient the multidisciplinary group chose just endoscopic and imaging follow-up, based on the benign nature of the lesion.

CONCLUSIONS

The biological characteristics of pancreatic PEComa remain an enigma. Its prognosis seems to depend on whether atypical ("worrisome") histological features are available or not. Surgery turned out as the most appropriate treatment, without reaching any agreement on surgery timing. Further studies on larger population are needed to better understand the biological features of pancreatic PEComa, in order to set up guidelines in the diagnosis, treatment and follow-up.

Primary malignant perivascular epithelioid cell neoplasm (PEComa) of the bone mimicking granular cell tumor in core biopsy: A case report and literature review

The present study investigated the case of a 46-year-old female with primary malignant perivascular epithelioid cell neoplasm (PEComa) of the femur. The patient presented with a 5-month history of right distal thigh pain following trauma. Radiographs of the right distal femur revealed a mixed lytic and sclerotic lesion with subtle areas of cortical destruction and soft tissue extension, consistent with an aggressive tumor. A core biopsy revealed an epithelioid tumor with granular cell features, but a definitive diagnosis could not be made. Due to the aggressive features on radiologic evaluation, the patient underwent a resection of the distal femur and reconstruction with a distal femoral megaprosthesis and hinged knee replacement. The post-resection pathology led to a final diagnosis of primary bone PEComa, with histologic features including epithelioid, granular cell and spindled cell morphologies and biphasic immunoreactivity for melanocytic and smooth muscle markers. The large tumor size (>5 cm), rapid mitotic rate, infiltrative growth pattern, high nuclear grade and cellularity, and the presence of necrosis rendered this a malignant PEComa. The present study discussed the case, including radiographic (radiographs, magnetic resonance imaging and positron emission tomography scans) and histologic appearance and a literature review.

Fat-Containing Liver Lesions on Imaging: Detection and Differential Diagnosis

OBJECTIVE

The purpose of this article is to review how fat is detected on imaging and to discuss the differential diagnosis of fat-containing liver lesions.

CONCLUSION

Fat is a highly useful feature in characterizing liver lesions on imaging. Although a variety of liver lesions can show fat on cross-sectional imaging, the presence of fat usually indicates that the lesion is of hepatocellular origin. Less commonly, nonhepatocellular fatty lesions may be distinguished by ancillary clinical and imaging features.

Renal angiomyolipoma without visible fat: Can we make the diagnosis using CT and MRI?

Renal angiomyolipomas without visible fat (AML.wovf) are benign masses that are incidentally discovered mainly in women. AML.wovf are typically homogeneously hyperdense on unenhanced CT without calcification or haemorrhage. Unenhanced CT pixel analysis is not useful for diagnosis. AML.wovf are characteristically homogeneously hypointense on T2-weighted (T2W)-MRI and apparent diffusion coefficient (ADC) maps. Despite early reports, only a minority of AML.wovf show signal intensity drop on chemical-shift MRI due to microscopic fat. AML.wovf most commonly show avid early enhancement with washout kinetics at contrast-enhanced CT and MRI. The combination of homogeneously low T2W and/or ADC signal intensity with avid early enhancement and washout is highly accurate for diagnosis of AML.wovf.

KEY POINTS

• AML.wovf are small incidental benign renal masses occurring mainly in women. • AML.wovf are homogeneously hyperdense with low signal on T2W-MRI and ADC map. • AML.wovf typically show avid early enhancement with washout kinetics. • Combining features on CT/MRI is accurate for diagnosis of AML.wovf.

Cardiac Perivascular Epithelioid Cell Tumor: Report of a Child and Review of the Literature

Cardiac tumors presenting as mediastinal masses in childhood are rare. This report describes the case of a 6-year-old girl who presented to us after a failed attempt at resection of a mass arising from the left atrial appendage. Computed tomography–guided biopsy suggested a perivascular epithelioid cell tumor (PEComa). Sirolimus was started in order to reduce the mass size. She subsequently underwent resection of the mass by midline sternotomy approach and cardiopulmonary bypass. Recovery was uneventful and the child is doing well at two-year follow-up. Contemporary literature is reviewed. Only seven cases, including two children, with mediastinal PEComa have been reported. Pathology and treatment options are discussed.

Malignant perivascular epitheloid cell tumour (PEComa) of the lung - a rare entity

Malignant Perivascular Epitheloid Cell Tumour (PEComa) of the lung is very rare, with only six cases reported in literature. This case presented with a large mass originating from right upper lobe of the lung with dilemma in its histopathological diagnosis and management. Postoperative histopathology after a right upper and middle lobectomy describes a tumour with an alveolar/nested pattern of growth and epitheloid morphology with expression of TFE-3 and diagnosed as PEComa. After 6 months the patient had a local recurrence inside the thorax & chest wall.This case qualifies it as a rare type of malignant PEComa with younger age of presentation, aggressive clinical behaviour & malignant histological features along with TFE3 positivity on immunohistochemistry. This case is probably the first of its kind with the largest reported size involving two lobes of the lung.

Benign clear cell "sugar" tumor of the lung in a patient with Birt-Hogg-Dubé syndrome: a case report

Background

Birt-Hogg-Dubé (BHD) syndrome is a rare inherited autosomal genodermatosis and caused by germline mutation of the folliculin (FLCN) gene, a tumor suppressor gene of which protein product is involved in mechanistic target of rapamycin (mTOR) signaling pathway regulating cell growth and metabolism. Clinical manifestations in BHD syndrome is characterized by fibrofolliculomas of the skin, pulmonary cysts with or without spontaneous pneumothorax, and renal neoplasms. There has been no pulmonary neoplasm reported in BHD syndrome, although the condition is due to deleterious sequence variants in a tumor suppressor gene. Here we report, for the first time to our knowledge, a patient with BHD syndrome who was complicated with a clear cell “sugar” tumor (CCST) of the lung, a benign tumor belonging to perivascular epithelioid cell tumors (PEComas) with frequent causative relation to tuberous sclerosis complex 1 (TSC1) or 2 (TSC2) gene.

Case presentation

In a 38-year-old Asian woman, two well-circumscribed nodules in the left lung and multiple thin-walled, irregularly shaped cysts on the basal and medial area of the lungs were disclosed by chest roentgenogram and computer-assisted tomography (CT) during a preoperative survey for a bilateral faucial tonsillectomy. Analysis of the resected tumor showed large polygonal cells with clear cytoplasm proliferating in a solid pattern. Immunohistochemistry revealed that these tumor cells were positive for microphthalmia-transcription factor, S100, and CD1a but negative for HMB45, indicating that the tumor was a CCST. Genetic testing indicated that the patient had a germline mutation on exon 12 of the FLCN gene, i.e., insertion of 7 nucleotides (CCACCCT) (c.1347_1353dupCCACCCT). Direct sequencing of the FLCN exon 12 using genomic DNA obtained from her microdissected CCST cells clearly revealed loss of the wild-type FLCN sequence, which confirmed complete functional loss of the FLCN gene. On the other hand, no loss of heterozygosity around TCS1- or TSC2-associated genetic region was demonstrated.

Conclusion

To our knowledge, this is the first report of CCST of the lung in a patient with BHDS, indicating that CCST should be added to the spectrum of pulmonary manifestations of BHDS.

[Renal epithelioid angiomyolipoma mimicking renal carcinoma]

L'angiomyolipome épithélioide est une forme rare d'angiomyolipome à potentiel malin, considéré récemment par l'OMS comme une entité à part dans la classification des tumeurs rénales. Cette lésion pose un problème dans le diagnostic différentiel avec les carcinomes à cellules claires. Il n'y a pas de critère spécifique clinique ou radiologique caractérisant cette tumeur. L'immunohistochimie en révélant la positivité des cellules épithélioide au marqueur HMB45 est essentielle au diagnostic. Le traitement doit être discuté en concertation pluridisciplinaire.

An Unusual Combination of Biliary Cystadenoma and Renal Angiomyolipoma- A Case Report

Hepatobiliary cystadenomas are mucinous cystic neoplasms arising in the liver, extrahepatic bile ducts or gall bladder. Extrahepatic cystadenomas are rare neoplasms requiring complete excision as there is a chance for recurrence and malignant transformation. Angiomyolipoma (AML) belongs to the perivascular epithelioid cell group of neoplasms, and kidney is the commonest site involved. We report a case of an unusual combination of extrahepatic biliary cystadenoma with angiomyolipoma in an adult female without evidence of tuberous sclerosis. The patient presented with abdominal discomfort and on ultrasonological examination showed a cyst close to liver suggestive of hydatid disease and an incidental mass in kidney which was diagnosed as angiomyolipoma. Histopathological examination revealed biliary cystadenoma of liver and renal angiomyolipoma. Clinical and radiological evaluation did not show any manifestations of tuberous sclerosis. Such an unusual incidence of two separate neoplasms in a patient without syndromic association was not obtained even after extensive literature search.

A systematic review: perivascular epithelioid cell tumor of gastrointestinal tract

Perivascular epithelioid cell tumor (PEComa) is a rare entity with distinctive morphology and of expressing myomelanocytic markers. Gastrointestinal tract (GI) is one of the most common anatomic sites of origin and counts for 20% to 25% of all reported cases of perivascular epithelioid cell tumors not otherwise specified (PEComas-NOS). However, the biologic behavior of perivascular epithelioid cell tumors of gastrointestinal tract (GI PEComas-NOS) is still unclear. The aim of conducting this systematic review is to sum up what is known so far of the epidemiology, natural history, management and prognosis of GI PEComas-NOS.A systematic research was performed on PubMed and EMBASE using the following terms: ("perivascular epithelioid cell tumor" or "PEComa") and ("gastrointestinal tract" or "GI" or "oral " or "mouth" or "esophagus" or "gullet" or "gastric" or "stomach" or "duodenum" or "jejunum" or "ileum" or "cecum" or "colon" or "colorectal" or "sigmoid" or "rectum" or "anus" or "mesentery") up to December 1, 2015. Retrieved GI PEComas-NOS publications, which included these terms, contains case reports, case series to case characteristic researches.A total of 168 articles were reviewed, 41 GI PEComa-NOS English studies among which were retrieved for analysis. We reviewed epidemiology, natural history, management and prognosis of GI PEComa-NOS. Generally GI PEComa-NOS is believed to have women predomination. The most frequently involved location is colon with non-specific clinical signs. Pathologically, GI PEComas-NOS shows epithelioid predominance (70%), meanwhile coexpresses melanocytic and muscle markers characteristically, while immunohistochemistry is a useful tool for identify, which indicates that HMB-45 is regarded as the most sensitive reagent. Complete resection served as mainstay of treatment, while chemotherapy should be unanimously considered to apply in malignant cases. Eventually, it is necessary for closed and long-term follow-up with endoscope and imaging for ruling out local recurrence or distant metastasis of this tumor.GI PEComas-NOS lives with unclear behavior. There are still many unverified clinicopathological issues of GI PEComas-NOS that needs to be clarified. Further studies and analyses concerning this rare entity should be brought out. Thus, the randomized clinical researches (RCTs) are required to be conducted.

Combination targeted therapy of VEGFR inhibitor, sorafenib, with an mTOR inhibitor, sirolimus induced a remakable response of rapid progressive Uterine PEComa

Perivascular epithelioid cell tumor is a rare tumor. To date, there is no consensus of therapy to be recommended for unresectable disease. For a low incidence and a rarely curable disease, the finding of new therapy is essential. Here we report the first case of a patient with perivascular epithelioid cell tumor whose disease had a rapid progression after surgery and had a rapid remarkable response of combination therapy of a VEGFR inhibitor, sorafenib, with an mTOR inhibitor, sirolimus. This result may have potential to deliver a new treatment option and inhibiting the mTOR pathway combined with inhibiting the VEGF pathways may be a useful strategy for malignant PEComas.

Hepatic multiple perivascular epithelioid cell neoplasm: A case report and literature review

Perivascular epithelioid cell neoplasm (PEComa) is a rare tumor type and primary hepatic multiple perivascular is rarer still. The present case report investigated the case of a 40-year-old woman who was admitted to The Second Xiangya Hospital for hepatic multiple tumor by physical examination without any history of abdominal pain or body weight loss. Abdominal plain computed tomography revealed three lesions in the liver. All lesions exhibited a well-defined boarder and only one mass contained fatty tissue in S6 of the liver. An enhanced scan revealed that all lesions were heterogeneous, and were enhanced on the artery phase and on portal vein phase. On delay phase, the lesions revealed continued enhancement, which is isoattenuating to the normal hepatic parenchyma. Following excision of the three masses, the patient was pathologically diagnosed with hepatic multiple PEComa. Short-term re-examination revealed no recurrence.

Hepatic falciform ligament clear cell myomelanocytic tumor: A case report and a comprehensive review of the literature on perivascular epithelioid cell tumors

Background

The objective of the study was to explore the clinical expression, radiological and pathological features, differential diagnosis, and biological behavior of a clear cell myomelanocytic tumor. In a case involving a clear cell myomelanocytic tumor located in the hepatic falciform ligament, we evaluated clinical expression, radiological characteristics, histopathology, immunohistochemistry, and biological behavior; we also reviewed the relevant literature.

Case presentation

Clear cell myomelanocytic tumor is a benign soft-tissue neoplasm that often occurs in women, and is expressed as a painless mass. The falciform ligament is its most frequent site of occurrence. The imaging characteristics of this lesion were uneven enhancement in the arterial phase, continuing to strengthen in the venous phase, and equal density in the balance phase. Histological and immunohistochemical analysis revealed the main transparent epithelioid cells and smooth muscle spindle cells to be HMB-45(+), smooth muscle actin(+), and melan-A (+).

Conclusion

Hepatic vascular epithelioid cell tumors are very rare mesenchymal neoplasms. Few studies have investigated this tumor in the hepatic falciform ligament; consequently, its diagnosis and the selection of an appropriate treatment and follow-up protocol are challenging. Treatment outcome remains unpredictable. Therefore, clear cell myomelanocytic tumor should be viewed as a tumor with uncertain malignant potential requiring long-term follow-up.

Primary retroperitoneal perivascular epithelioid cell neoplasm: A case report

Perivascular epithelioid cell neoplasm (PEComa) is a rare type of tumor, and primary retroperitoneal PEComa is rarer still. The present report discusses the case of a 51-year-old woman who was admitted to hospital following stiffness and discomfort in the upper right abdomen for longer than one month. Computed tomography identified a soft tissue mass in the rear right kidney, accompanied by clear cystic degeneration and bleeding. The borderline between the mass and the right kidney was not distinct. An enhanced scan revealed that the solid section of the mass was progressively enhanced. Following excision of the mass and the affected right kidney, the patient was pathologically diagnosed with retroperitoneal PEComa involving the right kidney. Short-term reexamination did not detect any recurrence.