Hepatic perivascular epithelioid cell tumor (PEComa): dynamic CT, MRI, ultrasonography, and pathologic features--analysis of 7 cases and review of the literature

Rare Encounter: A Case Report of Hepatic Perivascular Epithelioid Cell Tumor - An Uncommon Mesenchymal Tumor in the Liver

Introduction

Perivascular epithelioid cell tumor (PEComa) is a rare neoplastic mesenchymal tumor, more frequently found in the uterus, although it can occur in different organs. Hepatic PEComa is extremely rare, with only a few cases described in the literature.

Case Presentation

We present a case report of a 33-year-old female patient with a history of macroprolactinoma. She was initially referred to our Department due to a 9-mm hepatic nodule incidentally diagnosed in an abdominal ultrasound in 2018. She was asymptomatic. Follow-up ultrasound showed a growth from 9 mm to 16 mm in 2019 and 30 mm in a liver magnetic resonance imaging (MRI) scan in 2022. The case was discussed in a multidisciplinary team meeting, and since malignant transformation or hepatocellular carcinoma could not be ruled out, the decision was to undergo hepatic resection. An open hepatic subsegmentectomy of segment 5 was performed, with uneventful postoperative period. The definitive diagnosis was hepatic PEComa.

Conclusion

Hepatic PEComas are rare liver tumors, and their preoperative diagnosis is challenging due to the lack of specific radiological features. In most cases, the diagnosis is only confirmed through histopathological and immunohistochemical studies. Resection of the lesion appears to be the curative treatment; however, due to the rarity of the condition, there are no studies comparing surgical treatment with other options. In our case, the hypervascular lesion was initially misdiagnosed as an adenoma. PEComas should be considered as a differential diagnosis in liver nodules with well-defined margins and increased uptake in the arterial phase in computed tomography or MRI scan. Surgical resection was curative, and no recurrence was detected during the patient's follow-up.

Hepatic Perivascular Epithelioid Cell Tumor (PEComa): A Case Report

Perivascular epithelioid cell tumors (PEComas) are a rare group of mesenchymal neoplasms composed of perivascular epithelioid cells. While commonly found in the kidney, uterus, and soft tissues, PEComas of the liver are exceedingly rare.  We present a case of a PEComa incidentally discovered in a 73-year-old female patient undergoing evaluation for abdominal pain. Imaging revealed an indeterminant mass in the left hepatic lobe without internal color uptake on Doppler flow. Histopathological evaluation was consistent with PEComa. The tumor was mainly composed of well-circumscribed epithelioid and spindle cell lesions with smooth muscle differentiation. Immunohistochemical staining was positive for smooth muscle actin (SMA), human melanoma black 45 (HMB 45), and Melan A.  PEComas are usually detected incidentally during workup for other reasons. Diagnosis is based on histopathological evaluation, and although most of the cases reported in the literature were evaluated after surgical resection, some of them were diagnosed after the image-guided biopsies, as we did in our case. This entity of tumors needs further studies on their natural behavior, as some malignant cases were reported. In addition, a clearer approach to diagnosis and treatment needs to be established, and more prognostication tools and radiographic characterization are needed.

Case report: Liver PEComa after kidney transplantation in recipient with tuberous sclerosis complex

Introduction

Perivascular epithelioid cell tumors (PEComa) are rare tumors of mesenchymal origin that exhibit perivascular epithelioid cell phenotype. One of its most common localizations is uterus, whereas only a few studies reported PEComa localization as liver. There is a correlation between the presence of PEComa and tuberous sclerosis complex (TSC). TSC is a rare disease which leads to the development of mostly non-cancerous tumors in various organs. We would like to present a case of a kidney transplant recipient with a PEComa detected post-transplant in the liver.

Case report

A 27-year-old patient, 3 years after kidney transplantation (KTx) due to chronic renal failure in the course of autosomal dominant polycystic kidney disease and concomitant TSC, was admitted to the Clinic and Department of General and Transplant Surgery for abnormal findings in computed tomography (CT). A CT scan was conducted for oncological follow-up after a kidney transplant (KTx) because before the transplantation, a small cystic lesion measuring 7 mm in diameter was removed from the donor kidney and diagnosed as papillary renal cell carcinoma (PRCC). Two tumors in the liver were detected - one 27mm in diameter in segment VII/VIII and the other 8mm in diameter in segment II/III. Because of typical radiological signs hepatocellular carcinoma was suspected, but the serum level of alpha fetoprotein was within normal limits and liver function was preserved. The intraoperative biopsy and the radiofrequency ablation (RFA) of the larger tumor were performed three months later. In the histopathological examination benign PEComa (HMB45 +, Melan A +) was detected.

Conclusion

The oncological surveillance made it possible to detect liver lesion in early stage and in 3,5-year follow-up no sign of recurrence of PEComa was found. This case is the second to show RFA as treatment method of liver PEComa and first in kidney transplant recipient.

Clear cell myomelanocytic tumor of ligamentum teres

Clear cell myomelanocytic tumor (CCMMT) of the falciform ligament/ligamentum teres is a rare hepatic tumor, a variant of the perivascular epithelioid cell tumor (PEComa) family. CCMMT is the rarest variant of hepatic PEComas. Only a few cases of CCMMT have been reported in the English literature. Because of its rarity, less is known about its biological behavior. We present a case of a 31-year-old female who complained of abdominal pain, bilious vomiting, and abdominal fullness over two months. The radiological impression was of focal nodular hyperplasia. The histological examination of the resection specimen revealed a well-circumscribed tumor arranged in fascicles, sheets, and a whorling pattern. The tumor cells were spindle to epithelioid shaped with abundant clear to pale eosinophilic cytoplasm. The tumor cells expressed both myoid (smooth muscle actin) and melanocytic (MelanA and HMB45) markers, while they were negative for hepatocytic and vascular markers. Thus, based on histology and immunohistochemistry, a diagnosis of CCMMT was made. This case presents the diagnostic challenges of CCMMT and discusses the differential diagnosis with a literature review.

Hepatic perivascular epithelioid cell tumors: Benign, malignant, and uncertain malignant potential

In 2013, the World Health Organization defined perivascular epithelioid cell tumor (PEComa) as "a mesenchymal tumor which shows a local association with vessel walls and usually expresses melanocyte and smooth muscle markers." This generic definition seems to better fit the PEComa family, which includes angiomyolipoma, clear cell sugar tumor of the lung, lymphangioleiomyomatosis, and a group of histologically and immunophenotypically similar tumors that include primary extrapulmonary sugar tumor and clear cell myomelanocytic tumor. Clear cell tumors with this immunophenotypic pattern have also had their malignant variants described. When localizing to the liver, preoperative radiological diagnosis has proven to be very difficult, and most patients have been diagnosed with hepatocellular carcinoma, focal nodular hyperplasia, hemangioma, or hepatic adenoma based on imaging findings. Examples of a malignant variant of the liver have been described. Finally, reports of malignant variants of these lesions have increased in recent years. Therefore, we support the use of the Folpe criteria, which in 2005 established the criteria for categorizing a PEComa as benign, malignant, or of uncertain malignant potential. Although they are not considered ideal, they currently seem to be the best approach and could be used for the categorization of liver tumors.

Primary Liver Perivascular Epithelioid Cell Tumor (PEComa): Case Report and Literature Review

A primary liver perivascular epithelioid cell tumor (PEComa) is an extremely rare entity. In this article, we present a case report with a review of the literature on the patients diagnosed with primary liver PEComa and an elaboration of diagnostic and treatment modalities. A systematic literature search was conducted using the terms "perivascular epithelioid cell tumor", "PEComa", "liver", and "hepatic". All articles describing patients diagnosed with primary liver PEComa were included. We identified a total of 224 patients of primary liver PEComa from 75 articles and a case from the present study with a significant preponderance of females (ratio 4:1) and with a mean age of 45.3 ± 12.1 years. Most of the patients (114 out of 224, 50.9%) were asymptomatic. A total of 183 (81.3%) patients underwent surgical hepatic resection at the time of diagnosis, while 19 (8.4%) underwent surveillance. Recurrence and metastases were detected in seven (3.1%) and six (2.7%) patients, respectively. In conclusion, surgical resection remains the cornerstone of therapy; however, the presence of nonspecific imaging features makes it difficult to reach a definite diagnosis preoperatively. Therefore, a multidisciplinary approach should be the gold standard in selecting the treatment modality.

Multimodal imaging study of hepatic perivascular epithelioid cell tumors: a case report

Hepatic perivascular epithelioid cell tumors (PEComas) are rare interstitial tumors that are often misdiagnosed as hepatocellular carcinomas due to their unique vascular enhancement patterns. Herein, we present a case of a 61-year-old man who was incidentally found to have a lesion in the left medial segment of the liver during a chest computed tomography (CT) examination performed 4 days prior to his presentation for chest discomfort. Imaging revealed solid components with density similar to that of normal liver tissue and areas of low-density adipose tissue within the lesion. The solid components exhibited increased uptake of fluorine-18 fluorodeoxyglucose on positron emission tomography/CT. Magnetic resonance imaging demonstrated areas with unevenly high signal intensity in both T1-weighted imaging (T1WI) in-phase and T2-weighted imaging (T2WI) sequences, while T2WI in the opposite phase displayed areas with unevenly low signal intensity, indicating the presence of fatty components. Contrast-enhanced T1WI displayed a "fast in and fast out" enhancement pattern. These distinct imaging features contribute to the diagnosis of hepatic PEComas and distinguish it from hepatocellular carcinoma.

Hepatic epithelioid angiomyolipoma is scattered and unsuitable for surgery: a case report

Hepatic epithelioid angiomyolipoma (HEAML) is a rare tumour of mesenchymal tissue with a malignant tendency. Occurring most frequently in women, the relative incidence in men and women, according to incomplete statistics, is approximately 1:5. In rare cases, disease occurrence and development is hidden. Lesions are generally discovered as chance findings by patients; abdominal pain is the first symptom, and imaging has no specificity in diagnosing the disease. Therefore, great difficulties exist in the diagnosis and treatment of HEAML. Here, the case of a 51-year-old female patient with a history of hepatitis B, and abdominal pain over 8 months as the initial symptom, is described. The patient was found to have multiple intrahepatic angiomyolipoma. Due to the small and scattered foci, complete resection was impossible, and because of her history of hepatitis B, conservative treatment was undertaken, with the patient undergoing regular follow-up. When hepatic cell carcinoma could not be excluded, the patient was treated with transcatheter arterial chemoembolization. No tumour neogenesis or metastasis was detected at the 1-year follow-up.

Insights into clinical diagnosis and treatment of malignant hepatic perivascular epithelioid cell tumor

Perivascular epithelioid cell tumors (PEComas) are infrequent mesenchymal tumors. They are usually benign, and only a few are malignant. These tumors are more commonly found in middle-aged women. PEComas are mainly composed of differentiated perivascular epithelioid cells arranged radially around the vascular cavity, and they are usually positive for melanocyte markers and smooth muscle cell differentiation markers. Among the PEComas, hepatic PEComas generally have no obvious symptoms and no typical imaging manifestations. Malignant hepatic PEComas are even rarer. So, we explained our insights into clinical diagnosis and treatment of malignant hepatic PEComas, in order to help clinicians and pathologists to further understand PEComas.

Retrospective analysis of hepatic perivascular epithelioid cell tumour (PEComa) in a single centre for clinical diagnosis and treatment clinical diagnosis and treatment of hepatic PEComa

Our primary objective was to investigate the clinical features, diagnosis, treatment and prognosis of hepatic perivascular epithelioid cell tumour (PEComa).Thirty-five cases of pathologically proven hepatic PEComa that were treated in the Department of Hepatobiliary Centre of the First Affiliated Hospital of Nanjing Medical University from January 2008 to February 2019 were retrospectively analysed, and the literature was also reviewed.Twenty-nine females and 6 males were included in this study. The mean age of these patients was 48.0 years (range, 21-75 years). Thirteen patients complained of upper abdominal pain or discomfort, while others were accidentally discovered by imaging examination. Hepatic PEComas tended to occur in the right lobe of the liver (20 cases in the right lobe, 13 in the left lobe and 2 in the caudate lobe). Two cases were characterized by multiple tumours, and the remaining cases were single lesions (range, 1.2-12 cm). Only 8 cases were correctly diagnosed by the preoperative imaging examination, and the correct diagnosis rate was only 22.9%. The postoperative immunohistochemistry analysis showed that hepatic PEComas are positive for human melanoma black 45, Melan-A and smooth muscle actin, with the exception of 1 case that was negative for Melan-A. All patients undergoing an operation accepted regular follow-up, and the average time was 66.5 months (range, 3-132 months). Two patients who experienced tumour recurrence and 1 patient who died of cardiovascular disease, but the remaining patients showed no evidence of tumour recurrence or metastasis during the follow-up period.Hepatic PEComas are a rare type of tumours that mainly occur in young and middle-aged women. The lack of clinical manifestations and imaging findings increases the difficulty of determining a preoperative diagnosis, which mainly depends on the results of pathological examinations. Surgery is currently the only effective treatment, and long-term clinical follow-up is necessary due to the aggressive behaviour and relapse of hepatic PEComa in some patients.

Hepatic perivascular epithelioid cell tumor: Clinicopathological analysis of 26 cases with emphasis on disease management and prognosis

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is an uncommon tumor of mesenchymal origin. Cases of PEComa in the liver are extremely rare.

AIM

To analyze the clinicopathological features and treatment of hepatic PEComa and to evaluate the prognosis after different treatments.

METHODS

Clinical and pathological data of 26 patients with hepatic PEComa were collected. All cases were analyzed by immunohistochemistry and clinical follow-up.

RESULTS

This study included 17 females and 9 males, with a median age of 50 years. Lesions were located in the left hepatic lobe in 13 cases, in the right lobe in 11, and in the caudate lobe in 2. The median tumor diameter was 6.5 cm. Light microscopy revealed that the tumor cells were mainly composed of epithelioid cells. The cytoplasm contained heterogeneous eosinophilic granules. There were thick-walled blood vessels, around which tumor cells were radially arranged. Immunohistochemical analysis of pigment-derived and myogenic markers in PEComas revealed that 25 cases were HMB45 (+), 23 were Melan-A (+), and 22 SMA (+). TFE3 and Desmin were negative in all cases. All the fluorescence in situ hybridization samples were negative for TFE3 gene break-apart probe. Tumor tissues were collected by extended hepatic lobe resection or simple hepatic tumor resection as the main treatments. Median follow-up was 62.5 mo. None of the patients had metastasis or recurrence, and there were no deaths due to the disease.

CONCLUSION

Hepatic PEComa highly expresses melanin and smooth muscle markers, and generally exhibits an inert biological behavior. The prognosis after extended hepatic lobe resection and simple hepatic tumor resection is semblable.

PEComa-A Rare Liver Tumor

PEComa (perivascular epithelioid cell tumor) is a rare liver tumor. Decisions regarding patient management are currently based on a few small case series. The aim of this study was to report the clinicopathological features of PEComa in order to provide guidance for management, complemented by our own experience. This retrospective observational study included all patients with PEComa who underwent surgical treatment in two departments between 2002 and 2020. A total of 20 patients were diagnosed with PEComa following histopathological examination. The age of the patients ranged from 21 to 73 years. The majority of patients were women (85%). In most patients, the tumors were incidental. In diagnostic studies, PEComas with high arterial vascularization have been described. Liver resection was the treatment of choice. There was only one postoperative complication. During histopathological evaluation, tumors were composed mostly of epithelioid cells, rarely with spindle cell components, thick-walled vessels, and adipocytes in different proportions. Melanocytic markers (HMB45, MelanA) and at least one smooth muscle marker were expressed in all tumors. Features suggestive of malignancy were found in three cases. In conclusion, PEComa is a rare liver tumor that is usually diagnosed incidentally. In radiological studies, tumors with high arterial vascularization are observed. Liver resection is the treatment of choice.

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.

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.

Feasibility of laparoscopic isolated caudate lobe resection for rare hepatic mesenchymal neoplasms

BACKGROUND

Mesenchymal tumors such as perivascular epithelioid cell neoplasm (PEComa) and inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDC sarcoma) are relatively uncommon in the liver and are particularly rare in the caudate lobe. The clinical manifestations and available imaging tests lack specificity for hepatic mesenchymal tumors. To the best of our knowledge, no caudate PEComa or IPT-like FDC sarcoma has been completely resected by laparoscopy. The standard laparoscopic technique, surgical approaches, and tumor margins for potentially malignant or malignant caudate mesenchymal tumors are still being explored.

AIM

To assess both the safety and feasibility of laparoscopic resection for rare caudate mesenchymal neoplasms.

METHODS

Eleven patients who underwent isolated caudate lobe resection from 2003 to 2017 were identified from a prospective database. Three consecutive patients with rare caudate mesenchymal tumors underwent laparoscopic resection. Patient demographic data, intraoperative parameters, and postoperative outcomes were assessed and compared with the open surgery group.

RESULTS

All procedures for the three resection patients with caudate mesenchymal tumors were completed using a total laparoscopic technique by two different approaches. The average operative time was 226 min, and the estimated blood loss was 133 mL. The average length of postoperative hospital stay was 6.3 ± 0.3 d for the laparoscopy group and 15.5 ± 2.3 d for the open surgery group (P < 0.05). There were no perioperative complications or patient deaths in this series.

CONCLUSION

Laparoscopic isolated caudate lobe resection for rare mesenchymal neoplasms is a feasible and curative surgical option in selected patients.

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.

Hepatic perivascular epithelioid cell tumor: A case report

Perivascular epithelioid cell tumor (PEComa) of liver is extremely rare hepatic neoplasm with only 30 cases reported in the literature. These lesions are found mainly in young females and may present a potential pitfall in the characterisation of focal liver lesions. The biological behavior of PEComa varies from generally benign to rarely malignant and metastatic disease. We report a case of a patient with hepatic PEComa with the corresponding imaging findings on the ultrasound, contrast-enhanced ultrasound (CEUS) and hepatospecific MRI. After failed attempt to characterize the lesion by percutaneous biopsy, surgical resection was conducted and the final diagnosis was achieved.

Unresectable hepatic PEComa: a rare malignancy treated with stereotactic body radiation therapy (SBRT) followed by complete resection

BACKGROUND

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors occurring in various anatomic regions. Although diagnostic criteria and treatment management are not established, current treatment options consist of surgery and chemotherapy including mTOR inhibitors. Stereotactic body radiation therapy (SBRT) is a non-invasive ablative treatment which has shown excellent control rates for more common types of unresectable liver tumors and metastases. In this report we present a rare case of PEComa of the liver that was treated by stereotactic radiotherapy followed by resection. Staging and evaluation of treatment response was done by FDG-PET/CT. This case highlights the potential of SBRT as a neoadjuvant treatment even for rare liver malignancies. It is the first case of liver PEComa treated by SBRT and resection.

CASE PRESENTATION

A 52-year-old woman presented at an external hospital with abdominal pressure and pain in the right upper abdominal quadrant. A CT scan showed a 700 cm3 liver lesion in segment IV. In repeated biopsy in July 2015 histopathological workup showed a pleomorphic epitheloid tumor with small to medium sized cells expressing vimentin and melan-A while being negative for cytokeratin establishing the diagnosis of PEComa of the liver. To achieve high, ablative doses a stereotactic body radiotherapy (SBRT) technique was chosen consisting of 60Gy (biologically effective dose 105Gy) in 8 fractions of 7.5Gy. Radiotherapy planning was based on MRI resulting in a planning target volume (PTV) of 1944 cm3. Treatment toxicity was limited to a slight elevation of transaminases (grade 1 and 3). A complete resection was performed 21 weeks after radiotherapy confirmed by negative surgical margins. At last follow-up 21 months after therapy, MRI showed neither local nor distant tumor recurrence. The patient was in stable condition (ECOG 1) and without late radiation toxicity.

CONCLUSIONS

This is the first documented case of liver PEComa treated by SBRT and resection. A favorable post-treatment course demonstrates that SBRT is a potential neoadjuvant treatment that is capable of reducing an inoperable rare liver tumor to a resectable lesion.

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.

Hepatic perivascular epithelioid tumor (PEComa). A case report

A 37-year-old female had liver nodules found in an abdominal ultrasound scan. The radiological features were suggestive of hepatocellular adenomas, although there were some atypical findings. Two years later, one of the nodules showed dimensional progression and intralesional hemorrhage. The patient underwent a left hepatectomy and the postoperative course was uneventful. The histological exam and the immunohistochemistry were consistent with the diagnosis of PEComa. The PEComa is a mesenchymal tumor rarely described in the liver. The preoperative diagnosis of PEComa is very difficult and, with this report, the authors intend to increase the limited knowledge relating to natural history and optimal treatment of this rare condition.

Management of hepatic angiomyolipoma: A systematic review

Hepatic Angiomyolipoma (HAML) is a rare mesenchymal liver tumour assumed to be predominantly benign, although incidental cases with malignant behaviour such as invasive growth, recurrence after resection and metastases have been reported. The aim of this systematic review was to assess the biological behaviour, estimate the risk of HAML related mortality and recommend on a justifiable management strategy. We performed a systematic literature search in Embase, Medline, Web-of-Science, Scopus, Pubmed Publisher, Cochrane and Google Scholar. We included all articles published from inception until March 2016 which reported on follow-up of various treatment strategies. We included 18 articles reporting on 292 patients. Male:female ratio was estimated at 1:3 with gender not reported in 31 cases. Of 292 patients 247 were treated with surgery, including one liver transplant, seven with chemotherapy or Sirolimus, three with embolization, and 35 conservatively. Recurrence after resection was described in 6/247 (2.4%) with pathologically proven HAML resulting in metastases and death in 2/247 (mortality rate 0.8%). Progression was described in 6/35 patients treated conservatively (21.4%). Two of 12 patients with malignant behaviour of HAML had an epithelioid-type HAML, of the remaining 10 histological subtype was undefined. With a risk estimate of 0.8% in surgically treated patients HAML related mortality is very low. Biopsy is indicated when imaging is inconclusive. In case of certain HAML diagnosis on imaging conservative management with annual imaging is justified. Resection should be considered in case of symptoms, inconclusive biopsy or growth in follow-up.

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.

Hepatic perivascular epithelioid cell tumor: Case report and brief literature review

RATIONAL

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm which expresses both myogenic and melanocytic markers. PEComas are found in a variety locations in the body, but up to now only approximately 30 cases about hepatic perivascular epithelioid cell tumor are reported in English language worldwide.

PATIENT CONCERNS

A 32-year-old woman was admitted in our hospital with intermittent right upper quadrant pain for 1 month and recent (1 day) progressive deterioration.

DIAGNOSES

Based on the results of the laboratory examinations and the findings of the computed tomography, the diagnosis of hepatic hamartoma or the hepatocecullar carcinoma with hemorrhage was made.

INTERVENTIONS

The patient underwent a segmentectomy of the liver, and the finally diagnosis of hepatic PEComa was made with immunohistochemical confirmation with HMB-45 and SMA.

OUTCOMES

There is no clinical or radiographic evidence of recurrence 9 months after surgery.

LESSONS

This kind of tumor is extremely rare and the natural history of PEComa is uncertain, as the treatment protocol for hepatic PEComa has not reached a consensus. But the main treatment of the disease may be surgical resection. Only after long term follow-up can we know whether the tumor is benign or malignant. It appears that longer clinical follow-up is necessary in all patients with hepatic PEComas.

Diagnosis and treatment of hepatic perivascular epithelioid cell tumor: A case report and literature review

Liver perivascular epithelioid cell tumor is a rare liver mesenchymal tumor with an insidious onset. This entity is often misdiagnosed due to the lack of typical clinical symptoms and signs and the low diagnosis rate achieved by imaging examinations. Here we report a case of liver perivascular epithelioid cell tumor. We also performed a literature review to summarize and analyze the clinical characteristics and treatment of this disease.

Intrahepatic peribiliary perivascular epithelioid cell tumor (PEComa) associated with heterotopic pancreas: A case report

Background

Perivascular epithelioid-cell tumor (PEComa) is a group of rare mesenchymal neoplasms that express myomelanocytic-cell markers and exhibit a wide variety of histopathological features. Although heterotopic pancreas has been reported to occur in the gastrointestinal tract, intrahepatic heterotopic pancreas has been reported only rarely.

Case presentation

We present a case of intrahepatic PEComa that showed a strong regional correlation with the presence of heterotopic pancreas. An intrahepatic tumor and biliary dilatation was incidentally discovered during a diagnostic evaluation to investigate low-back pain in a 47-year-old Japanese male. Cholangiocarcinoma was suspected and a left hemihepatectomy performed. Histological examination revealed a 3 × 3.8-mm tumor in the neighboring B2 bile duct. Histological and immunohistochemical investigations revealed the presence of a PEComa and pancreatic acini within the tumor mass. PEComa in the hepatobiliary and pancreatic regions are extremely rare. The presence of heterotopic pancreas is also relatively uncommon.

Conclusion

The strong regional association of these 2 lesions raises the possibility of a PEComa originating from heterotopic pancreas or from an irritable response caused by heterotopic pancreas.

Update on the imaging of malignant perivascular epithelioid cell tumors (PEComas)

Malignant perivascular epithelioid cell tumors (PEComas) are a histologic group of mesenchymal neoplasms that share a distinctive histological phenotype, the perivascular epithelioid cell. These tumors are known for their perivascular distribution. Malignant PEComas have a female predominance and are associated with aggressive disease and poor prognosis, making timely diagnosis critical to management. Imaging features of malignant PEComas are nonspecific and mimic other benign and malignant neoplasms. Surgery is the mainstay in the management of malignant PEComas. Promising novel molecular targeted therapies like m-TOR inhibitors have been shown to be effective in the metastatic setting. The aim of this review is to familiarize radiologists with the imaging appearances of and potential therapies for primary and metastatic malignant PEComa.

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.

PEComa in a Young Patient with Known Li-Fraumeni Syndrome

Perivascular epithelioid cells neoplasms (PEComas) constitute a family of rare tumours which have been reported virtually in all anatomic sites. The histological clarification of the malignant potential of these tumours is still problematic despite the proposed risk stratification systems. Li-Fraumeni syndrome (LFS) is caused by a germline mutation in the TP53 tumour suppressor gene. It is a rare but well-characterized cancer predisposition syndrome leading to the development of a variety of different tumour types. To the best of our knowledge, an association between this syndrome and PEComas has not been previously documented. A 24-year-old lady with known LFS presented with two uncertain-in-nature lesions, one within the right part of the liver and one within the upper pole of the right kidney. The patient underwent an uncomplicated open simultaneous right partial nephrectomy and resection of segment 7 of the liver. The morphological and immunohistochemical features of both lesions were of epithelioid angiomyolipoma (PEComa). Although the obvious scenario was that the liver lesion was a metastasis from the renal lesion, the assessment of their malignant potential according to the existing risk stratification systems was rather in favour of two synchronous primary PEComas, pointing out that the histological assessment of malignant potential of PEComas is still problematic.

Pancreatic perivascular epithelioid cell tumour presenting with upper gastrointestinal bleeding

PEComa is a family of rare mesenchymal tumours which can occur in any part of the human body. Primary PEComas of the pancreas are extremely rare tumours with uncertain malignant potential. A 17-year-old female was admitted to the hospital due to melena. She required several transfusions. CT scan demonstrated a mass at the head of the pancreas measuring 4.2 cm in maximum diameter. An endoscopic ultrasound showed an ulcerating malignant looking mass infiltrating 50% of the wall of the second part of the duodenum in the region of the ampulla. Multiple biopsies taken showed extensive ulceration with granulation tissue formation and underlying large macrophages without being able to establish a definite diagnosis. We proceeded with pylorus-preserving pancreaticoduodenectomy. The postoperative course of the patient was unremarkable, and she was discharged on the 8th postoperative day. Histology examination of the specimen showed a PEComa of pancreas. Eighteen months after resection the patient is disease free. To the best of our knowledge this is the first time we describe a case of a pancreatic PEComa presenting with massive gastrointestinal bleeding.

Hepatic PEComa: a potential pitfall in the evaluation of hepatic neoplasms

Perivascular epithelioid cell tumour (PEComa) of the liver is very uncommon and may be overlooked in the clinical and histological differential diagnosis of a liver tumour. We report the case of an incidentally discovered liver mass suspicious for hepatocellular carcinoma, which on biopsy was suggestive of a pseudocyst but after resection was found to be hepatic PEComa with some of the usual characteristics of this neoplasm as well as several less familiar features. We have also reviewed cases of hepatic PEComa from the literature in order to provide insight into recognising possible PEComa preoperatively and assessing its risk of malignancy after diagnosis.

PEComa: A Perivascular Epithelioid Cell Tumor in the Liver-A Case Report and Review of the Literature

Perivascular epithelioid cell tumors are soft tissue tumors that can occur in various locations in the body whose incidence is rising. Hepatic PEComas are quite rare and diagnosis involves positivity of Melan-A and HMB45 on immunohistochemistry. Usual treatment is surgery for benign tumors and chemotherapy including mTOR inhibitors for malignant tumors. Here we discuss the radiological and pathological diagnosis, evaluation, and management of a hepatic PEComa. We describe a 51-year-old patient who was diagnosed incidentally after unusual physical exam findings.

Management of perivascular epithelioid cell tumor of the liver: A case report and review of the literature

Perivascular epithelioid cell tumor (PEComa) is a rare tumor that originates from mesenchymal tissues. Cases of PEComa in the liver are extremely rare. The present study aimed to analyze the clinical features of PEComa in the liver and discuss its management. Here we report a 25-year-old female with multiple lesions of low density with poorly defined borders in the liver, as shown by a computed tomography (CT) scan. A partial hepatectomy was proceeded and PEComa was diagnosed by immunohistochemistry. No evidence of recurrence was observed during the one year follow-up. A total of 20 patients with hepatic PEComa, including one case from the present study and 19 cases that were reported in literature between June 2001 and December 2012, were reviewed and analyzed. The mean patient age was 43.4 years (range, 25-67 years) and the cases consisted of 18 female and two male patients. The tumor size ranged between 2.0×1.6 and 15.0×12.0 cm. Of the 20 patients, nine were asymptomatic and 11 had mild to significant complaints. Immunohistochemistry plays a key role in the diagnosis of PEComa. All the cases in this study were strongly positive for human melanoma black-45. A surgical resection is the gold standard for curative intent. All the patients underwent a surgical resection and none were administered perioperative chemotherapy or radiotherapy. In total, 13 of the 14 patients with follow-up information survived during the 8-36-month follow-up period and one patient succumbed due to recurrence two years after the surgery.