Transurethral en bloc resection of a bladder perivascular epithelioid cell tumor (PEComa): a case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor with distinct histologic and immunologic features. PEComas that originate in the bladder are extremely rare clinically, with only 35 cases reported in the English literature thus far. Here, we report a case of bladder PEComa resection by transurethral en bloc resection of bladder tumor (ERBT).

CASE PRESENTATION

A 66-year-old female with a history of poorly controlled type 2 diabetes with associated complications of frequent urinary tract infections presented to our hospital for a routine physical examination. Outpatient ultrasound examination revealed a strong echogenic mass of approximately 1.5 × 1.3 × 1.3 cm in size on the posterior wall of the bladder. The enhanced computed tomography and enhanced magnetic resonance imaging after admission both suggested a well-defined isolated nodular mass on the posterior wall of the bladder with significant enhancement on the enhanced scan. The tumor was successfully and completely resected by ERBT. Postoperative pathological examination and immunohistochemical results confirmed the mass was a bladder PEComa. No tumor recurrence was observed in the six-month postoperative follow-up.

CONCLUSION

Bladder PEComa is an extremely rare mesenchymal tumor of the urinary system. When imaging and cystoscopy reveal a nodular mass with an abundant blood supply in the bladder, PEComa should be included in the differential diagnosis of bladder tumors. Surgical resection is currently the primary option for the treatment of bladder PEComa. For a solitary, pedunculated, narrow-based, small-sized bladder PEComa, resection of the tumor by ERBT was a safe and feasible approach in our patient and may be considered for similar cases in the future.

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.

Primary Xp11 translocation PEComa of the testis with SFPQ⁃TFE3 rearrangement: a case report and review of the literature

BACKGROUND

Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal tumors with features of both smooth muscle and melanocytic differentiation. A subset of PEComas demonstrate rearrangements involving the TFE3 (Xp11) locus. Xp11 translocation PEComa is a rare neoplasm with special clinicopathological features and a more aggressive behavior. We recently encountered a case of Xp11 translocation PEComa occurring in the testis, with SFPQ⁃TFE3 rearrangement.

CASE PRESENTATION

A 57-year-old male touched a mass in his testis incidentally. MRI revealed a 10 mm diameter mass in the right testis. The patient underwent radical orchiectomy. Gross examination revealed a well-demarcated mass from the surrounding testicular tissue. Microscopically, the tumor mainly displayed nested or sheet-like architecture separated by delicate fibrovascular septa. The tumor cells exhibited marked nuclear atypia and pleomorphism. Immunohistochemistry showed that the tumor cells were strongly positive for cathepsin-K, HMB45 and TFE3. Molecular analysis revealed SFPQ⁃TFE3 gene fusion. Thus, it was diagnosed as primary Xp11 translocation PEComa of the testis.

CONCLUSIONS

The present case reports primary Xp11 translocation PEComa of the testis for the first time, which to our knowledge has not been described in the literature in this anatomic site, where it could potentially be problematic in diagnosis.

Perivascular epithelioid cell tumor of the uterine cervix identified on the liquid-based cytology: a case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) occurring in the female genital tract are rare, and typically found in the uterine corpus. PEComa occurring in the cervix is extremely rare, and very few cases have been reported till now. Cytological diagnosis of cervical PEComa is even rarer. So far, only two cases of PEComa diagnosed by conventional cervical smears have been reported.

CASE PRESENTATION

A 55-year-old postmenopausal woman presented with abnormal vagina discharge for 3 months. A liquid-based cytology test was performed. Microscopically, some loosely cohesive epithelioid cells were uniform with abundant clear cytoplasm, showing predominantly round or oval nuclei with finely stippled chromatin. Distinct round nucleoli were visible in some cells, notably with numerous melanin pigments in the cytoplasm. The cytopathological features were well correlated with cell block and histopathological findings. Upon immunohistochemistry (IHC), the tumor cells were positive for HMB45 and TFE3, focally positive for MelanA, while negative for muscle marker. Fluorescence in situ hybridization (FISH) confirmed TFE3 gene rearrangement. The final pathological diagnosis was PEComa identified by the liquid-based cytology, cell block, cervical biopsy, IHC and FISH result. The patient underwent a total hysterectomy with bilateral salpingo-oophorectomy and was followed up for 2 years with no evidence of disease.

CONCLUSION

The cytologic characteristics of the tumor can provide sufficient clues for PEComa diagnosis, which includes loosely cohesive, epithelioid morphology with abundant clear or eosinophilic cytoplasm, low-grade nuclear atypia, cytoplasmic melanin pigments. This will help cytopathologists to recognize this rare tumor that occurred in the cervix, and the combination of predictive morphology evaluation, immunophenotype, and molecular testing can achieve the definitive diagnosis of PEComa.

Dermatologic Disease-Directed Targeted Therapy (D3T2): The Application of Biomarker-Based Precision Medicine for the Personalized Treatment of Skin Conditions-Precision Dermatology

Precision dermatology uses individualized dermatologic disease-directed targeted therapy (D³T²) for the management of dermatoses and for the evaluation and therapy of cutaneous malignancies. Personalized/precision strategies are based on biomarkers that are most frequently derived from tissue transcriptomic expression or genomic sequencing or from circulating cytokines. For instance, the pathologic diagnosis of a pigmented lesion and determining the prognosis of a malignant melanocytic neoplasm can be enhanced by genomic/transcriptomic analysis. In addition to biopsy, innovative techniques have been developed for obtaining transcriptomes in skin conditions; as an example, patches can be applied to a psoriasis plaque for a few minutes to capture the epidermis/upper dermis transcriptome. Atopic dermatitis and prurigo nodularis may also be candidate conditions for precision dermatology. Precision dermatology has a role in managing melanoma and nonmelanoma skin cancers and rare cutaneous tumors-such as perivascular epithelioid cell tumor (PEComa)-that can originate in or metastasize to the skin. For instance, advanced/metastatic basal cell carcinomas can be treated with Hedgehog inhibitors (vismodegib and sonidegib) targeting the smoothened (SMO) or patched 1 (PTCH1) gene alterations that are a hallmark of these cancers and activate the Hedgehog pathway. Advanced/metastatic basal and cutaneous squamous cell cancers often have a high tumor mutational burden (which predicts immunotherapy response); immune checkpoint blockade with cemiplimab, a programmed cell death protein 1 (PD1) inhibitor, is now approved for these malignancies. Gene expression profiling of primary cutaneous squamous cell carcinoma can identify those individuals at high risk for subsequent metastases. In the realm of rare neoplasms, PEComas-which can originate in the skin, albeit uncommonly-have tuberous sclerosis complex 1 (TSC1)/tuberous sclerosis complex 2 (TSC2) gene alterations, which activate mammalian target of rapamycin (mTOR) signaling, and can be suppressed by nab-sirolimus, now approved for this condition. In summary, precision dermatologic techniques/strategies are an important emerging approach for evaluation and management of skin disorders and cutaneous neoplasms, and may serve as a paradigm for the application of precision medicine beyond dermatology.

Pediatric case of colonic perivascular epithelioid cell tumor complicated with intussusception and anal incarceration: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) represents a group of rare mesenchymal tumors. PEComa can occur in many organs but is rare in the colorectum, especially in children. Furthermore, PEComa is a rare cause of intussusception, the telescoping of a segment of the gastrointestinal tract into an adjacent one. We describe a rare case of pediatric PEComa complicated with intussusception and anal incarceration, and conduct a review of the current literature.

CASE SUMMARY

A 12-year-old girl presented with abdominal pain and abdominal ultrasound suggested intussusception. Endoscopic direct-vision intussusception treatment and colonoscopy was performed. A spherical tumor was discovered in the transverse colon and removed by surgery. Postoperative pathologic analyses revealed that the tumor volume was 5.0 cm × 4.5 cm × 3.0 cm and the tumor tissue was located in the submucosa of the colon, arranged in an alveolar pattern. The cell morphology was regular, no neoplastic necrosis was observed, and nuclear fission was rare. The immunohistochemical staining results were as follows: Human melanoma black 45 (HMB 45) (+), cluster of differentiation 31 (CD31) (+), cytokeratin (-), melanoma-associated antigen recognized by T cells (-), smooth muscle actin (-), molleya (-), desmin (-), S-100 (-), CD117 (-), and Ki67 (positive rate in hot spot < 5%). Combined with the results of pathology and immunohistochemistry, we diagnosed the tumor as PEComa. Postoperative recovery was good at the 4 mo follow-up.

CONCLUSION

The diagnosis of PEComa mainly depends on pathology and immunohistochemistry. Radical resection is the preferred treatment method.

Hepatic perivascular epithelioid cell tumor: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor with histologic and immunophenotypic characteristics of perivascular epithelioid cells, has a low incidence, and can involve multiple organs. PEComa originating in the liver is extremely rare, with most cases being benign, and only a few cases are malignant. Good outcomes are achieved with radical surgical resection, but there is no effective treatment for some large tumors and specific locations that are contraindicated for surgery.

CASE SUMMARY

A 32-year-old woman was admitted to our hospital with a palpable abdominal mass and progressive deterioration since the previous month. An ultrasound-guided percutaneous liver aspiration biopsy was performed. Postoperative pathological immunohistochemical staining was HMB45, Melan-A, and smooth muscle actin positive. Perivascular epithelioid tumor was diagnosed. The tumor was large and could not be completely resected by surgery. Further digital subtraction angiography revealed a rich tumor blood supply, and interventional embolization followed by surgery was recommended. Finally, the patient underwent transarterial embolization (TAE) combined with sorafenib for four cycles. Angiography reexamination indicated no clear vascular staining of the tumor, and the tumor had shrunk. The patient was followed up for a short period of time, achieved a stable condition, and surgery was recommended.

CONCLUSION

Adjuvant combination treatment with TAE and sorafenib is safe and feasible as it shrinks the tumor preoperatively and facilitates surgery.

A successful case of complete surgical resection via left upper and right lower lobectomy for bilateral lung metastases of a perivascular epithelioid cell tumor in the colon: a case report

Background

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms with malignant potential. No effective treatment other than surgical resection has been established for lung metastases of PEComas. We describe a patient who underwent complete surgical resection via bilateral lobectomy involving a two-step procedure for lung metastases 8 years after undergoing radical surgery for a colonic PEComa.

Case presentation

A 53-year-old woman underwent partial colectomy for a PEComa in the transverse colon 8 years ago. She presented with an abnormal chest shadow during a health examination. Chest computed tomography (CT) revealed a solid nodule 2 cm in diameter located centrally in the right lower lobe and a solid nodule 3 cm in diameter located centrally in the left upper lobe. Positron emission tomography revealed 18F-fluorodeoxyglucose uptake in these nodules. These nodules were suspected to be metastatic tumors of the colonic PEComa and were considered for complete surgical resection. Segmentectomy could not be performed because of the anatomical location of the tumors straddling the segments; therefore, bilateral lobectomy was required for complete surgical resection. Therefore, we performed two-step lobectomy safely with the expectation of pulmonary function recovery. Microscopically, the tumors were diagnosed as lung metastases of the PEComa. One year after the last surgery, no recurrence was detected, and the patient’s pulmonary function improved.

Conclusions

This case indicates that even if multiple lung metastases of a PEComa require bilateral lobectomy, complete resection with a two-step surgery may be considered.

Perivascular Epithelioid Cell Tumor of Urinary Bladder

OBJECTIVES

To review the clinicopathologic features of perivascular epithelioid cell tumor (PEComa) of the urinary bladder.

METHODS

Seven cases of bladder PEComa were studied by light microscopy, immunohistochemistry, and fluorescence in situ hybridization (FISH).

RESULTS

In our 7 cases, 5 patients were female and 2 were male, with ages between 26 and 78 years. Patients presented with hematuria and recurrent abdominal discomfort as the main clinical symptoms. Microscopically, the epithelioid and spindle-shaped tumor cells with clear to granular eosinophilic cytoplasm were arranged in fascicular, acinar, or nested patterns. The tumor cells were positive for HMB45, melan-A, and SMA, but no TFE3 gene rearrangement was detected in any of the 7 samples by FISH. The analysis of all 35 cases from the literature and ours showed a patient age range from 16 to 78 years (mean age, 39 years), a male-to-female ratio of 1:1.3, maximal tumor diameters from 0.6 to 18.8 cm (mean, 4.5 cm). With a mean follow-up of 27 months, the recurrence, metastasis, and mortality rates were 10.7%, 10.7%, and 7.1%, respectively.

CONCLUSIONS

Bladder PEComa is extremely rare, remains a diagnostic challenge, and needs more attention. Strengthening the understanding of this tumor will improve diagnostic accuracy.

Clinicopathological correlation and post-resection outcomes of hepatic angiomyolipoma

Backgrounds/Aims

Angiomyolipoma is a rare neoplasm of mesenchymal origin derived from perivascular epithelioid cells. Due to rarity, hepatic angiomyolipoma (HAML) has been often misdiagnosed as hepatocellular carcinoma (HCC) or other hypervascular liver tumors based on imaging studies. This study investigated the clinicopathological correlation and post-resection outcomes of HAML.

Methods

This retrospective observational study included 40 patients who underwent hepatic resection (HR) for HAML between 2008 and 2018.

Results

Mean age of the patients was 42.6±11.4 years and there were 30 (75.0%) females. Hepatitis B and C virus infection was present in 8 patients (20.0%) and 1 patient (2.5%), respectively. Preoperative diagnoses on imaging studies were HCC in 23 (57.5%) patients, HAML in 14 (35.0%) patients, focal nodular hyperplasia in 2 (5.0%) patients, and hepatic adenoma in 1 (2.5%) patient. Percutaneous liver biopsy was performed in 10 (25.0%) patients and HAML was diagnosed in all patients. Only 3 patients (7.5%) showed a slight elevation in the level of liver tumor markers. Major HR was performed in 10 (25.0%). Laparoscopic HR was performed in 9 (22.5%). The mean tumor size was 4.8±3.9 cm and single tumor was present in 38 (95.0%) patients. Currently, all the patients are alive without tumor recurrence during the follow-up observation period of 75.7±37.3 months.

Conclusions

HAML is a rare form of primary liver tumor and is often misdiagnosed as HCC or other hypervascular tumors. Although HAML is benign in nature, it has malignant potential, thus resection is indicated if the tumor grows or malignancy cannot be excluded.

Perivascular epithelioid cell tumor (PEComa) of the kidney: an overview of its management and outcomes

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor with unique histological and immunohistochemical characteristics. Malignant renal cell carcinoma is even rarer and its biological behavior is still not clear. We report here a case of malignant PEComa in a male patient. The first symptom of the patient was intermittent hematuria. Ultrasound and computed tomography scan showed a solid mass in the left kidney. Fibrosarcoma was initially diagnosed after radical resection of the tumor. Six years later, the patient had a tumor recurrence and underwent a second operation, through which the diagnosis of renal malignant PEComa was made. Since then, the patient received chemotherapy, a third operation, and interventional treatment because of recurrence and metastasis of the tumor, which prolonged the life of the patient for another 6 years. Malignant PEComa involving the kidney is very rare; it seems to develop slowly but will recur and metastasize. At present, surgical resection remains the best treatment.

Perirenal perivascular epithelioid cell tumor (PEComa)

A 52-year-old woman, who is a carrier of MLH-1 mutation (HNPCC-type Lynch syndrome) with a history of colon adenocarcinoma, was diagnosed with a 26 mm lobulated contrast-capturing mass located caudally of the pancreas tail, anteromedial of the spleen and medial of the splenic colon angle. She underwent an exploratory laparotomy with resection of the tumor. Initially, this mass was presumed to be metastasis in a patient with a history of colon adenocarcinoma. However, after further histopathological and immunohistochemical examination, the mass appeared to be a rare PEComa. Only a few cases of a PEComa in this retroperitoneal perirenal location have been described.

Simultaneous diagnosis of liver PEComa in a family with known Li-Fraumeni syndrome: a case report

Background

Li–Fraumeni syndrome (LFS) is an autosomal dominant hereditary disease. It is associated with the loss of function of the p53 protein and an increased risk of malignant tumor development at early age. The most frequently detected tumors include breast cancer, sarcomas, leukemia, brain tumors, and adrenocortical carcinomas. While sarcomas account for only 1% of solid tumors, they are more frequently detected in these families.

Case presentation

We report a simultaneous diagnosis of hepatic perivascular epithelioid cell tumor (PEComa), a very rare subtype of sarcoma, in two siblings with a LFS.

Conclusions

The simultaneous diagnosis of PEComa in two siblings presented in this case allowed us to review the frequency of PEComa in this genetic syndrome previously reported, which was very little. Despite its rarity, PEComa must be considered in the differential diagnosis of new-onset liver lesions in patients who were previously diagnosed with LFS.

TFE3-expressing malignant perivascular epithelioid cell tumor of the mesentery: A case report and review of literature

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor that exhibits an epithelioid and spindle cell morphology. The tumor is characterized by immunoreactivity for melanocytic and myogenic markers but can be misdiagnosed as more common tumors with similar characteristics, including gastrointestinal stroma tumors or leiomyosarcomas. Recently, a subset of PEComas has been reported to harbor a transcription factor binding to TFE3 fusion. Herein, we report a rare case of TFE3-expressing malignant PEComa arising from the mesentery.

CASE SUMMARY

A 50-year-old woman presented with abdominal discomfort for 3 months. Results of laboratory tests were all within the normal ranges, and the patient had no notable medical history. Magnetic resonance imaging revealed a large tumor on the right side of the pelvic floor, which was originally suspected to be a primary ovarian tumor. However, during surgery, the tumor was revealed to have originated from the mesentery. Histologically, the tumor was composed of bundles of spindle cells and sheets of epithelioid cells. Extensive coagulative necrosis and numerous mitotic figures were observed. Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin, HMB-45, and TFE3 expression. Tumor involvement of the rectal serosa was identified, leading to a final diagnosis of malignant PEComa of the mesentery. Surgical resection was followed by adjuvant chemotherapy. No recurrence or metastasis was observed over a 6-month follow-up period.

CONCLUSION

Malignant PEComa of the mesentery is extremely rare and should be distinguished from morphological mimics through differential diagnosis and immunohistochemistry.

Cytopathology of extra-renal perivascular epithelioid cell tumor (PEComa): a series of 7 cases and review of the literature

INTRODUCTION

Perivascular epithelioid cell tumor (PEComa) is a family of rare mesenchymal tumors consisting of histologically and immunohistochemically distinctive perivascular epithelioid cells. Relatively little is known about the cytopathology of extra-renal PEComas. Because of a considerable range of morphology and their rarity, accurate cytologic classification can be challenging. We evaluated cytologic characteristics and diagnostic pitfalls of extra-renal PEComas on fine-needle aspiration (FNA).

MATERIALS AND METHODS

We performed a retrospective search in our cytopathology and surgical pathology database for cases diagnosed as PEComa that had corresponding cytology specimens from 3 medical institutions. All available cytopathology specimens were reviewed. We evaluated cytologic characteristics and recorded histologic diagnoses and immunohistochemical stains.

RESULTS

Seven FNA specimens from 6 patients were identified, and cytologic diagnoses were made in all cases as follows: PEComa (4 cases), most consistent with PEComa (1 case), malignant neoplasm (1 case), and hepatocellular carcinoma (1 case). Most specimens were moderately to highly cellular. Cell distribution occurred as tissue fragments with background proliferating capillaries. Most smears were composed of epithelioid cells showing mild to moderate anisonucleosis, abundant eosinophilic cytoplasm, well-defined borders, intranuclear pseudoinclusions, and prominent nucleoli. A combination of myoid and melanocytic markers was expressed in 6 cases except 1 case, which was called hepatocellular carcinoma.

CONCLUSIONS

This was the largest FNA series for extra-renal PEComas to date. Our study highlights some common cytomorphologic characteristics of PEComa with which cytopathologists should be familiar. In the right clinical and radiologic context, and with the aid of immunohistochemistry, a definitive diagnosis can be achieved.

Angiomyolipoma of the Nasal Cavity: A Distinct Entity. A Case Report and Literature Review

Angiomyolipoma (AML) is a mesenchymal tumor commonly found in the kidneys. Extra-renal AML is uncommon and especially rare in the nasal cavity. To our knowledge, fewer than five cases of nasal AML are reported in the United States. We present a case of nasal AML in a 65-year-old man with a history of rhinosinusitis and obstruction of the left nasal cavity. The lesion comprised of admixed spindled smooth muscle cells, mature adipose tissue, and thick-walled blood vessels. Smooth muscle differentiation of the spindled cells was confirmed by expression of smooth muscle actin. Surprisingly, melanocytic markers, such as HMB45, were negative. The histologic features and immunoprofile suggest that nasal AML is pathologically distinct from neoplastic AMLs/perivascular epithelioid cell tumors (PEComas) that typically occur in the kidney. We propose that nasal AML is a hamartomatous lesion rather than neoplastic. Although AML is rare in the nasal cavity, it should be considered in the differential diagnosis of clinically benign nasal masses.

[Uterine malignant perivascular epithelioid cell tumor (PEComa): Two case reports]

Tumors of the perivascular epithelioid cells (PEComa) of the uterus are rare mesenchymal tumors that are characterized by the expression of both melanocyte and smooth muscle markers. It is often difficult to distinguish PEComas from other uterine tumors: endometrial stromal sarcoma, smooth muscle tumors including epithelioid tumors, melanoma and clear cell sarcoma. We report two cases of malignant PEComas of the uterus, treated in two different hospitals, found in women over 60, presenting a clinical picture of metrorrhagia in a context of myomatous uterus. In the first case, the histological examination of the hysterectomy specimen found a diffuse proliferation of epithelioid cells expressing HMB45. In the second case, the question of the differential diagnosis of the PEComa with a uterine epithelioid leiomyosarcoma arose, in front of the weak or even absent expression of the melanocytic immunohistochemical markers (melanA negative and focal HMB 45). The opinion requested from a network of experts (RRePS) had made it possible to validate the diagnosis of PEComa, notably by carrying out a complement of immunohistochemistry (expression of cathepsin K) by the tumor cells. In spite of its rarity, the diagnosis of PEComa should be considered before this type of epithelioid or clear cell uterine tumor because of the possibility of treatment by targeted therapies such as the mTOR (mammalian target of rapamycin) inhibitors.

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

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

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

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

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

Robotic wedge resection of a rare gastric perivascular epithelioid cell tumor: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that can arise in many different organs with a broad spectrum of biological behavior, from indolent to aggressive progression. Only ten cases of gastric PEComas have been reported in the English literature, which were treated with endoscopic, laparoscopic, or open resections. Due to its rarity, the optimal surgical management and prognosis of this tumor are still uncertain.

CASE SUMMARY

We present a case of robotic wedge resection of a 6.5 cm bleeding lesion of the gastric fundus located 3 cm below the esophago-gastric junction in a 55-year-old man. Biopsy revealed a malignant tumor with epithelioid cells focally positive for muscle markers desmin and smooth muscle actin. In addition, histology revealed that the tumor was positive for HMB-45, melan-A (MART-1), microphthalmia transcription factor and negative for pan-cytokeratin AE1/AE3, CD34, p40, DOG-1, CD117 (c-kit), S100, CD3, CD79a, caldesmon and myogenin. These markers suggested the possibility of a PEComa. The patient underwent a diagnostic laparoscopy via the da Vinci® Si™ system and robotic wedge resection. Final pathology confirmed a malignant gastric PEComa with negative margins. At his 11-mo follow-up visit, the patient remained disease-free.

CONCLUSION

Gastric PEComa can be treated with a robotic R0 resection with acceptable postoperative and short-term oncological outcomes.

Perivascular epitheliod cell tumors: Study of three gynecological cases

ANTECEDENTS

Perivascular epitheliod cell tumor (PEComa) is a rare mesenchymal tumor. They are rare in the field of gynecology, which makes them difficult to consider as a possible diagnostic. We aim to contribute with our experience to ease clinical practice to others gynecologists.

PATIENTS AND METHODS

We contribute to literature with three gynecological cases; uterine, vaginal and retroperitoneal PEComas.

RESULTS

The uterine and vaginal PEComa, have required surgical treatment, and are free of disease at 9 and 5 months respectively. The retroperitoneal PEComa has recurred at 72 months of follow-up in form of retroperitoneal mass and pulmonary lymphangioleomyomatosis, continues treatment with sirolimus with good tolerance and partial response.

DISCUSSION

Given the scarcity of cases, the literature consists of case reports and mini-reviews. Some authors have categorized the PEComas based on prognostic factors, but there is no agreement regarding the follow-up and treatment. ¹⁸F-FDG-PET/CT can help characterize these lesions. The surgery is the standard. In recurrent or malignant cases, there is a lack of evidence regarding chemotherapy and radiotherapy. New therapies with inhibitory m-TOR open a hopeful therapeutic window.

Malignant perivascular epithelioid cell tumor of the lung synchronous with a primary adenocarcinoma: one case report and review of the literature

BACKGROUND

Perivascular Epithelioid Cell Tumors (PEComa) is an extraordinarily rare mesenchymal neoplasm especially the malignant type originating from the lung. To date, only 8 cases of malignant or malignant potential pulmonary PEComa had been documented. Firm diagnostic criteria for malignant pulmonary PEComa need urgently to be established.

CASE PRESENTATION

We report a challenging case of malignant pulmonary PEComa combined with a primary adenocarcinoma in a 54-year-old man. The PEComa-like tumor showed strong Melan-A and weak transcription factor E3 (TFE3) protein expression but no TFE3 gene rearrangement. The carcinoma-like nodule was recognized as a poorly differentiated primary lung adenocarcinoma.

DISCUSSION AND CONCLUSIONS

Our case report was the first case of malignant pulmonary PEComa synchronous with a primary adenocarcinoma and studied the dilemma of diagnosing benign versus malignant criteria for this uncommon tumor.

Melanotic Xp11-associated tumor of the sigmoid colon: A case report

BACKGROUND

Melanotic Xp11-associated tumors are rare mesenchymal-derived tumors. So far, most primary melanotic Xp11-associated tumors have been reported in the kidney, and reports of this tumor in the gastrointestinal tract are rare.

CASE SUMMARY

Here we describe the case of a 25-year-old woman who presented with a melanotic Xp11-associated tumor in the sigmoid colon. Colonoscopy revealed a large mucosal bulge in the sigmoid colon, approximately 32 cm inside the anus. The surface was rough with local erosion. The tumor was brittle on biopsy and bled easily. Computed tomography revealed thickening of the rectal wall with edema. Postoperative pathology indicated the likelihood of a perivascular epithelioid cell tumor. Histologically, the tumor comprised plump epithelioid cells with abundant clear to lightly eosinophilic cytoplasm and round nuclei arranged in an alveolar or trabecular pattern. The tumor cells were strongly positive for HMB-45, Melan-A, Cathepsin K, and TFE3 but negative for vimentin, smooth muscle actin, S100 protein, CD10, CK20, and desmin. The tumor cells had a low Ki-67 labeling index (approximately 2%). Fluorescence in situ hybridization revealed TFE3 fracture. Based on these histologic and immunohistochemical features, a diagnosis of melanotic Xp11-associated tumor of the sigmoid colon was made.

CONCLUSION

In summary, we report the clinicopathological features of a primary tumor that is extremely rare in the sigmoid colon and review the clinicopathological characteristics of melanotic Xp11-associated tumors, compatible with the very rare tumor termed “melanotic Xp11 translocation renal cancer” in all aspects.

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.

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

Background

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

Case presentation

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

Conclusions

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

Expanding the histomorphologic spectrum of TFE3-rearranged perivascular epithelioid cell tumors

Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal neoplasms that have smooth muscle and melanocytic differentiation. They can be sporadic or associated with tuberous sclerosis complex and commonly present in the kidney as angiomyolipoma or in the lung as pulmonary clear cell sugar tumors or lymphangioleiomyomatosis. However, they can present at any visceral or soft tissue site. They usually have a benign clinical course, but rarely can behave in a malignant fashion. Most PEComas demonstrate abnormalities of TSC2, but a recently described subset harbor TFE3 rearrangements that seem to be mutually exclusive of TSC2 alterations. TFE3-rearranged PEComas demonstrate a distinct alveolar morphology that lacks spindle cells and smooth muscle differentiation. Distinction between these may have important therapeutic consequences. Herein, we present a case of a TFE3-rearranged PEComa without the customary morphology that required ancillary investigation with TFE3 immunohistochemistry and break-apart fluorescence in situ hybridization for proper categorization.

Giant Perivascular Epithelioid Cell Tumor of the Orbit: A Clinicopathological Analysis and Review of the Literature

Aim

To describe and review the clinical, radiological, and histopathological characteristics of an orbital perivascular epithelioid cell tumor (PEComa).

Methods

A systematic review of clinical records, radiological investigations, microscopic features, and immunohistochemical characteristics was done.

Results

A 9-year-old female child presented with a year-long history of a large orbital mass associated with painless, progressive proptosis of the right eye. Radiologically, a well-defined orbital mass was seen with no intracranial extension. Excision was performed and histopathological examination showed uniform epithelioid cells in nests separated by thin fibrovascular septae. The tumor cells stained positively for Human Melanoma Black-45, but neg-atively for desmin, S-100, smooth muscle actin, MyoD1, microphthalmia-associated transcription factor, vimentin, CD10, CD31, and CD34 with a low proliferation index of 5-7%. Based on the tumor's morphological and immuno-histochemical characteristics, a diagnosis of giant orbital PEComa was made. No recurrence was seen at the last follow-up.

Conclusions

PEComas are uncommon mesenchymal neoplasms that have typical histological features, with an immunohistochemical profile of negativity for epithelial markers and positivity for melanocytic markers. For benign PEComas, complete excision is advised. However, since PEComas elsewhere in the body have been known to be malignant, a close follow-up of such cases is recommended.

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.

Ang-1 and Ang-2 expression in angiomyolipoma and PEComa family tumors

OBJECTIVE

Perivascular epithelioid cell tumors (PEComa) are an uncommon family of soft tissue tumors. Previously, we described that the presence of pericyte antigens among PEComa family tumors differs extensively by histologic appearance.

METHODS

Here, we extend our findings using the pericyte antigens Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2), using immunohistochemical detection in human tumor samples.

RESULTS

While Ang-1 showed no expression across any PEComa family tumor, Ang-2 showed expression that like other pericyte markers was largely determined by cytologic appearance.

CONCLUSION/IMPLICATIONS

Pericytic marker expression in PEComa may represent a true pericytic cell of origin, or alternatively aberrant pericyte marker adoption.

Perivascular epithelioid cell tumor of the descending colon mimicking a gastrointestinal stromal tumor: a case report

BACKGROUND

We present a case of perivascular epithelioid cell tumor (PEComa), which clinically and histologically mimics a gastrointestinal stromal tumor (GIST).

CASE PRESENTATION

A 42-year-old woman was found to have a mass in the left flank during her annual medical checkup. Computed tomography examination revealed a submucosal tumor of the descending colon. Surgeons and radiologists suspected that the lesion was a GIST, and left hemicolectomy was performed without biopsy. Microscopic examination showed that the lesion was composed of spindle and epithelioid cells, which were immunohistochemically negative for c-kit and positive for platelet-derived growth factor receptor (PDGFR) α. Initial diagnosis of PDGFRα-positive GIST was made. However, gene analysis did not reveal mutations in PDGFRα. Additional immunohistochemistry showed that tumor cells were positive for human melanin black 45 (HMB45), melanA, and the myogenic marker calponin. A final diagnosis of PEComa was made.

CONCLUSION

PEComa should be included in the differential diagnosis of PDGFRα-positive spindle cell tumors in the wall of the gastrointestinal tract.

Perivascular epithelial cell tumor (PEComa) of the pancreas: a case report and review of previous literatures

Perivascular epithelial cell tumors (PEComas), firstly described by Bonetti in 1992, are a family of mesenchymal tumor composed of perivascular epithelioid cells having epithelioid or spindle morphology and exhibiting melanocytic and myogenic immunoreactivities. We herein described a 61-year-old woman who presented with epigastric pain. Preoperative imaging studies showed that 7-cm-sized mass was located in pancreatic head and body, and pancreaticoduodenectomy was performed. Histological findings showed that the tumor was composed of clear epithelioid cells with abundant glycogen granules, which grew in a nested and alveolar pattern around blood vessels. The tumor cells showed immunoreactivities for HMB-45 but did not express epithelial or endocrine markers. These histological features indicated those of PEComa. This report underlines that we should recognize PEComa as a preoperative differential diagnosis of pancreatic tumors.

Pancreatic perivascular epithelioid cell tumor: A case report with clinicopathological features and a literature review

Perivascular epithelioid cell tumor (PEComa) of the pancreas is an unusual tumor deriving from mesenchyma. This paper described a case of pancreatic PEComa, which was initially suspected as neuroendocrine carcinoma by biopsy, and therefore surgical treatment was recommended due to undetermined diagnosis. Examination of the surgical specimen under a microscope showed that the tumor cell’s morphology was epithelioid or spindle-shaped, and ranged in a nested pattern. Additionally, these cells had a large extent of acidophilic cytoplasm, no mitotic figures, and expressed HMB-45, melan-p, and smooth muscle actin immunohistochemically. Pathological examination indicated that PEComa originated from the pancreas, but symptoms related to tuberous sclerosis were absent. Since PEComa is extremely rare in the pancreas, it is likely to be ignored in differential diagnosis. In conclusion, our article highlighted the clinicopathological features of PEComa, and we conducted a literature review focusing on PEComa so as to deepen the understanding of this tumor type.

Cutaneous perivascular epithelioid cell tumors: A review on an infrequent neoplasm

“Perivascular epithelioid cutaneous” cell tumors (PEComa) are a family of mesenchymal tumors with shared microscopic and immunohistochemical properties: They exhibit both smooth muscle cell and melanocytic differentiation. Non-neoplastic counterpart of PEComa’s cells are unknown, as well as the relationship between extracutaneous PEComa and primary cutaneous ones. We will review the clinical setting, histopathologic features, chromosomal abnormalities, differential diagnosis and treatment options for cutaneous PEComa.

Malignant Perivascular Epithelioid Cell Neoplasm (PEComa) of the Pelvis: A Case Report

Perivascular epithelioid cell neoplasms (PEComa) are rare mesenchymal tumors that can occur in any part of the body and have unpredictable pathological behavior. They are usually benign, but may be malignant. We present a case of malignant PEComa of the pelvic retroperitoneum treated with radical surgery.

Expression of CD44 and CD29 by PEComa cells suggests their possible origin of mesenchymal stem cells

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. The perivascular epithelioid cell (PEC) co-expresses melanocytic and muscle markers. Since no normal counterpart to the PEC has ever been identified in any normal tissue, the cell origin of these tumors is still uncertain. Although, several hypotheses have recently been advanced to explain the histogenesis of PEComa, it remains unclear.

METHODS

The aim of this study was to discuss whether differential expression of stem cell-associated proteins could be used to aid in determining the histogenesis of PEComa. For this purpose, we detected the immunoexpression of 5 kinds of stem cell markers on PEComas, including CD29, CD44, CD133, ALDH1, and nestin. In addition to observed histopathologic morphology, we also performed PEComa relevant clinical diagnostic markers (HMB-45, SMA, melan-A, Desmin, Ki-67, S-100 and TFE3) to identify whether they belonged to PEComas.

RESULTS

Our study included 13 PEComa samples, and we obtained positive immunoexpression results as follows: CD29 (13/13), CD44 (8/13), ALDH1 (10/13), nestin (1/13), and CD133 (0/13).

CONCLUSIONS

Since CD44 and CD29 are surface proteins associated with MSCs, these results suggest that PEComa might arise from MSCs. However, whether MSCs are the origin of PEComa needs to be further explored in the future.

Perivascular epithelioid cell tumor in the duodenum: challenge in differential diagnosis

Defined as a family of scarce mesenchymal neoplasm which distinctively co-express melanocytic markers and muscle markers, perivascular epithelioid cell tumors (PEComas) have been reported almost everybody site. Perivascular epithelioid cell tumors-not otherwise specified (PEComas-NOS) arising in the gastrointestinal (GI) tract are still restricted into sporadic case reports. Herein we present a case of GI PEComas-NOS which occurs in the duodenum of a 27-year-old male. Our initial diagnosis tended to gastrointestinal stromal tumor or smooth muscle tumor till the correct diagnosis of perivascular epithelioid cell tumor (PEComa) was established by postoperative pathological examination. We also make a literature review of GI PEComas-NOS and highlight the challenge it brings to the differential diagnosis.

Malignant hepatic perivascular epithelioid cell tumor (PEComa) - Case report and a brief review

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms which can arise from almost any location in the body. Diagnosing them pre-operatively is difficult as they mimic features of other hepatic neoplasms including hepatocellular carcinoma (HCC), fibrolamellar HCC, and focal nodular hyperplasia (FNH) among others. The unique feature of these tumors is the coexpression of muscle and melanocytic markers. These are identified immunohistochemically by the expression of Human Melanin Black-45 (HMB-45), Melan-A and Smooth Muscle Antigen (SMA) which are seen in the majority of tumors. The liver is uncommonly associated with a PEComa and the approach to a patient with hepatic PEComa is not well described. There is no consensus regarding the neo-adjuvant/adjuvant therapy in these patients. The natural history of this condition is not well documented making it an unpredictable disease. Here we have discussed a case and reviewed the literature concerning these rare tumors.

PEComa: morphology and genetics of a complex tumor family. Ann Diagn Pathol. 2015;19:359-368. [PMID: 26144278 DOI: 10.1016/j.anndiagpath.2015.06.003]

Perivascular epithelioid cell tumors, or PEComas, are mesenchymal neoplasms composed of histologically and immunohistochemically distinctive epithelioid or spindle cells, which are immunoreactive for both smooth muscle and melanocytic markers. The cells in PEComas are typically arranged around blood vessels and appear to form the vessel wall, often infiltrating the smooth muscle of small- to medium-sized vessels. Periluminal cells are usually epithelioid and the more peripheral cells are spindle shaped. The cells have small, round to oval nuclei, sometimes with focal nuclear atypia, and clear to eosinophilic cytoplasm, and no counterpart normal cell has been identified. The PEComa "family" now includes angiomyolipoma, pulmonary clear cell "sugar" tumor and lymphangioleiomyomatosis, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, abdominopelvic sarcoma of perivascular epithelioid cells, and other tumors with similar features at various sites that are simply termed PEComa. Some PEComas occur in patients with tuberous sclerosis complex and share the genetic abnormalities. There is a behavioral spectrum from benign to frankly malignant, and histologic criteria have been proposed for assessing malignant potential. The differential diagnosis can include carcinomas, smooth muscle tumors, other clear cell neoplasms, and adipocytic tumors. PEComas constitute a genetically diverse group that includes neoplasms harboring TFE3 gene rearrangements and those with TSC2 mutations, indicating alternative tumorigenic pathways. Recent advances in therapy of malignant PEComas relate to increased knowledge of specific genetic changes and their effects on metabolic pathways that are susceptible to specific interventions. We review PEComas, emphasizing the diagnostic spectrum and recent immunohistochemical and genetic findings.

Improving recognition of hepatic perivascular epithelioid cell tumor: Case report and literature review

A 58-year-old man presented with the chief complaint of abdominal bloating and was incidentally found to have a liver tumor. As diagnostic imaging studies could not rule out malignancy, the patient underwent partial resection of segment 3 of the liver. The lesion pathologically showed eosinophilic proliferation, in addition to immunohistochemical positivity for human melanoma black 45 and Melan-A, thereby leading to the diagnosis of a hepatic perivascular epithelioid cell tumor (PEComa). A PEComa arising from the liver is relatively rare. Moreover, the name ‘PEComa’ has not yet been widely recognized, and the same disease entity has been called epithelioid angiomyolipoma (EAML), further diminishing the recognition of PEComa. In addition, PEComa imaging findings mimic those of malignant liver tumors, and clinically, this tumor tends to enlarge. Therefore, a PEComa is difficult to diagnose. We conducted a systematic review of PEComa and EAML cases and discuss the results, including findings useful for differentiating perivascular epithelioid cell tumors from malignant liver tumors.

Coincidence between malignant perivascular epithelioid cell tumor arising in the gastric serosa and lung adenocarcinoma

A 4-mo history of both epigastralgia and back pain was presented in a 39-year-old male. Computed tomography showed right lung nodule and abdominal mass attached to the gastric wall, measuring approximately 30 mm and 70 mm in diameter. Since biopsy samples from the lung and abdomen revealed poorly differentiated adenocarcinoma and malignant tumor, clinicians first interpreted the abdominal mass as metastatic carcinoma, and a right lower lobectomy with following resection of the mass was performed. Gross examination of both lesions displayed gray-whitish to yellow-whitish cut surfaces with hemorrhagic and necrotic foci, and the mass attached to the serosa of the lesser curvature on the gastric body. On microscopic examination, the lung tumor was composed of a proliferation of highly atypical epithelial cells having abundant eosinophilic cytoplasm, predominantly arranged in an acinar or solid growth pattern with vessel permeation, while the abdominal tumor consisted of sheets or nests with markedly atypical epithelioid cells having pleomorphic nuclei and abundant eosinophilic to clear cytoplasm focally in a radial perivascular or infiltrative growth pattern. Immunohistochemically, the latter cells were positive for HMB45 or α-smooth muscle actin, but the former ones not. Therefore, we finally made a diagnosis of malignant perivascular epithelioid cell tumor (PEComa) arising in the gastric serosa, combined with primary lung adenocarcinoma. Furthermore, small papillary carcinoma of the thyroid gland was identified. The current case describes the coincidence of malignant PEComa with other carcinomas, posing a challenge in distinction from metastatic tumor disease.

Perivascular Epithelioid Cell Tumor Arising from Ciliary Body Treated by Local Resection

AIMS

Perivascular epithelioid cell tumor (PEComa) is a mesenchymal neoplasm originating from perivascular myoid cells. We report a case of PEComa arising from the ciliary body.

METHODS

Case report.

RESULTS

A 13-year-old girl was referred to our department with a clinical diagnosis of ciliary body melanoma in her right eye. Her visual acuity was 20/600 OD. Slit-lamp examination revealed a brown tumor behind the iris. The ocular fundus could not be observed due to a cataract. Ultrasonography depicted an oval mass approximately 10 mm in diameter at the ciliary body. The tumor was successfully treated by local resection, and the patient's visual acuity improved to 20/20. Histopathological and immunohistochemical findings of the excised tumor were compatible with the diagnosis of PEComa of the ciliary body. No local recurrence of the tumor was observed for over 4 years after surgery.

CONCLUSION

A very rare case of PEComa of the ciliary body was successfully treated by local resection, with favorable visual outcome and no recurrence for several years. PEComa can be differentiated from other ciliary body tumors by immunohistochemical study.

Malignant perivascular epithelioid cell tumor of the kidney with rare pulmonary and ileum metastases

AIMS

To report one case of malignant perivascular epithelioid cell tumor (PEComa) of the kidney with rare pulmonary and ileum metastases and analyze its clinicopathological features.

METHODS

We analyzed the clinicopathological features of one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Immunohistochemistry staining was performed.

RESULTS

The patient was a 48-year-old man with a renal mass approximately 14 cm × 11 cm × 8 cm in size. Microscopically, the tumor was mainly composed of polygonal epithelioid cells with dense eosinophilic cytoplasm and round nuclei with small nucleoli. Focal tumor cells showed pleomorphism with multinucleated giant cells and prominent nucleoli. The tumor cells nests were surrounded by thick-walled irregular blood vessels. Focal fat cells were found within the tumor. Hemorrhage and coagulative necrosis were also present. The tumor cells were positive for vimentin, HMB45, and Melan-A, and focally positive for SMA and S-100 protein. After 5 years and 5.6 years of nephrectomy, the tumor metastasized to the right lung and ileum, respectively.

CONCLUSION

We first reported one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Metastatic PEComa of the lung and ileum should differentiate from primary carcinoma, metastatic carcinoma, malignant melanoma, and gastrointestinal stromal tumor.

Targeted therapies in rare sarcomas: IMT, ASPS, SFT, PEComa, and CCS

This article highlights the data currently available on the activity of targeted medical treatment in a subgroup of rare entities within soft tissue sarcomas, including inflammatory myofibroblastic tumor, alveolar soft part sarcoma, solitary fibrous tumor, malignant perivascular epithelioid cell tumor (PEComa), and clear cell sarcoma.

Fertility sparing treatment of a malignant uterine perivascular epithelioid cell tumor: A case report

•Perivascular epithelioid cell tumors (PEComas) are a family of rare, poorly defined mesenchymal tumors of uncertain malignant potential.•Treatment for PEComas has most commonly involved excisional biopsy or surgical resection.•The use of mTOR inhibitors may provide the best medical treatment as well as a fertility-sparing treatment option.

PEComa of the colon resistant to sirolimus but responsive to doxorubicin/ifosfamide

A 23-year-old male presented with a three-week-history of crampy abdominal pain and melaena. Colonoscopy revealed a friable mass filling the entire lumen of the cecum; histologically, it was classified as perivascular epithelioid cell tumor (PEComa). An magnetic resonance imaging scan showed, in addition to the primary tumor, two large mesenteric lymph node metastases and four metastatic lesions in the liver. The patient underwent right hemicolectomy and left hemihepatectomy combined with wedge resections of metastases in the right lobe of the liver, the resection status was R0. Subsequently, the patient was treated with sirolimus. After 4 mo of adjuvant mammalian target of rapamycin inhibition he developed two new liver metastases and a local pelvic recurrence. The visible tumor formations were again excised surgically, this time the resection status was R2 with regard to the pelvic recurrence. The patient was treated with 12 cycles of doxorubicin and ifosfamide under which the disease was stable for 9 mo. The clinical course was then determined by rapid tumor growth in the pelvic cavity. Second line chemotherapy with gemcitabine and docetaxel was ineffective, and the patient died 23 mo after the onset of disease. This case report adds evidence that, in malignant PEComa, the mainstay of treatment is curative surgery. If not achievable, the effects of adjuvant or palliative chemotherapy are unpredictable.

Perivascular epithelioid cell tumor of male pelvic cavity: a case report and literature review

Perivascular epithelioid cell tumors (PEComas) are a family of rare mesenchymal neoplasms. The PEComas, composed of epithelioid and spindle cells, have the same cellular and immunohistochemical features but are found in different visceral and soft tissue sites. Here, we report the histological and immunohistochemical features of one case of PEComa restricted in the pelvic visceral peritoneum of a male patient. The patient was treated with radical surgery, and was well and on follow-up visits without tumor recurrence.

Hepatic epithelioid angiomyolipoma: an analysis of two cases

AIM: To investigate the clinicopathologic characteristics of hepatic epithelioid angiomyolipoma (EAML).

METHODS: Two cases of hepatic EAML treated at General Hospital of Wuhan Iron and Steel Corporation from 2007 to 2009 were analyzed in this study. The clinicopathologic and immunohistochemical characteristics of the disease were described and the related literature was reviewed.

RESULTS: Both patients are female. Both cases of hepatic EAML had clear boundaries. The tumors were characterized by diffused epithelioid neoplastic cells. The epithelioid cells were round with eosinophilic or clear cytoplasm, and few neoplastic cells showed cellular atypia. Immunohistochemically, the neoplastic cells were diffusely positive for HMB45, Melan-A and SMA.

CONCLUSION: Hepatic EAML is a rare mesenchymal neoplasm. The diagnosis and differentiatial diagnosis of EAML rely mainly on histopathology and immunohistochemistry.

Clinicopathologic features of perivascular epithelioid cell tumor of the pancreas

AIM: To investigate the clinicopathologic features, diagnosis, treatment and prognosis of perivascular epithelioid cell tumor (PEComa) of the pancreas.

METHODS: One case of PEComa of the pancreas was investigated by light microscopy and immunohistochemistry. A literature review was performed to summarize the characteristics of the disease.

RESULTS: The tumor was located in the head of the pancreas. Microscopically, the lesion was composed of thick or thin blood vessels and nest- or slice-shaped cells around the blood vessels. The tumor cells were huge, showed different polygons and had abundant clear to eosinophilic, granular cytoplasm. The nuclei were polymorphic and no mitoses were observed. Immunohistochemistrically, the tumor cells were strongly positive for HMB45, Melan-A, SMA, HHF35 and vimentin, weakly positive for D2-40 and S-100, and negative for Syn, CK (Pan), CD117, CD34, insuin, somatostatin, gastrin, calcitonin, α-hCG, ACTH, serotonin, PP, VIP and glucagon.

CONCLUSION: Pancreatic PEComa is a mesenchymal tumor with undetermined biological behavior and has unique histological, immunohistochemical and ultrastructural features. There are no definitely diagnostic criteria currently available to differentiate malignant and benign pancreatic PEComa. Current management has relied on surgery, and postoperative long-term close follow-up is needed.