PEComas: the past, the present and the future

Immunophenotypic analysis of angiomyolipoma with epithelial cysts, comparison to mixed epithelial and stromal tumors and epithelial and stromal elements of normal kidney and ovaries

Angiomyolipoma with epithelial cysts (AMLEC) is a rare variant of renal angiomyolipoma (AML). It is characterized by a conventional AML component admixed with epithelial cysts within an "ovarian-like" stroma. Mixed epithelial and stromal tumor (MEST) is another renal neoplasm featuring epithelial cysts and "ovarian-like" stroma. While there is consensus that in MEST the epithelial and stromal components are neoplastic, in AMLEC it has been hypothesized that the epithelial component may represent renal tubular entrapment or ovarian-like transdifferentiation of tumor cells. The aim of this study was to compare the immunophenotypes of the epithelial-stromal components of AMLEC and MEST, with normal kidney and ovary to provide additional insights into the pathogenesis and relationships of these entities. In this study, we analyzed eight cases of AMLEC and 14 cases of MEST from 2003 to 2023. We used tissue microarrays, full sections, or unstained slides with an immunohistochemical panel including renal and ovarian markers: SF1, ER, PR, AR, PAX8, WT1, GATA3, CA-IX, p16, inhibin A, and BCL2. We compared these cases with ten non-neoplastic ovary and kidney samples. Our findings indicate that the epithelial component of AMLEC and MEST resembles hormone receptor positive renal tubular epithelium (AR + /ER - /PR -). AMLEC's stromal component resembled hormone receptor positive renal stroma, while MEST's resembled ovarian stroma, supporting mullerian transdifferentiation. Our study showed that the epithelial and stromal components of AMLEC and MEST are immunophenotypically different and also differ from normal tissues. Our findings suggest that in AMLEC, the epithelial-stromal component represents a hormonally driven proliferation of non-neoplastic renal elements within a dysregulated tumor microenvironment.

Primary omental smooth muscle tumor in an adult male: a diagnostic dilemma for leiomyoma: a case report

BACKGROUND

The greater omentum comprises peritoneal, adipose, vascular, and lymphoid tissues. Most omental malignancies are metastatic tumors, and the incidence of primary tumors is rare. We report on a prior omental smooth muscle tumor case in an adult male patient.

CASE PRESENTATION

A 54-year-old Japanese male patient with no relevant medical history was diagnosed with an abdominal mass during a routine medical checkup. Subsequent contrast-enhanced computed tomography revealed a mass of approximately 3 cm in size in the greater omentum, and a laparotomy was performed. A 27 × 25 × 20 mm raised lesion was found in the omentum. Microscopically, spindle cells were observed and arranged in whorls and fascicles. Individual tumor cells had short spindle-shaped nuclei with slightly increased chromatin and were characterized by a slightly eosinophilic, spindle-shaped cytoplasm. The mitotic count was less than 1 per 50 high-power fields. The tumor cells showed positive immunoreactivity for α smooth muscle actin, HHF35, and desmin on immunohistochemical examination. The Ki-67 labeling index using the average method was 1.76% (261/14806). No immunoreactivity was observed for any of the other tested markers. We considered leiomyoma owing to a lack of malignant findings. However, primary omental leiomyoma has rarely been reported, and it can be difficult to completely rule out the malignant potential of smooth muscle tumors in soft tissues. Our patient was decisively diagnosed with a primary omental smooth muscle tumor considering leiomyoma. Consequently, the patient did not undergo additional adjuvant therapy and was followed up. The patient was satisfied with treatment and showed neither recurrence nor metastasis at the 13-month postoperative follow-up.

DISCUSSION AND CONCLUSION

We encountered a primary smooth muscle tumor of the greater omentum with no histological findings suggestive of malignancy in an adult male patient. However, omental smooth muscle tumors are extremely difficult to define as benign, requiring careful diagnosis. Further case reports with long-term follow-up and case series are required to determine whether a true omental benign smooth muscle tumor (leiomyoma) exists. In addition, proper interpretation of the Ki-67 labeling index should be established. This case study is a foundation for future research.

Hepatic perivascular epithelioid cell tumors: The importance of preoperative diagnosis

Accurate preoperative diagnosis is highly important for the treatment of perivascular epithelioid cell tumors (PEComas) because PEComas are mainly benign tumors and may not require surgical intervention. By analyzing the causes, properties and clinical manifestations of PEComas, we summarize the challenges and solutions in the diagnosis of PEComas.

Epithelioid angiomyolipoma of the liver in a patient with Li-Fraumeni syndrome: a case report

BACKGROUND

Epithelioid angiomyolipoma (EAML) is a rare variant of angiomyolipoma that predominantly consists of epithelioid cells and belongs to the perivascular epithelioid cell neoplasm (PEComa) family. The majority of EAMLs arise in the kidneys, and primary hepatic EAML appears to be much less common than renal EAML. Most PEComas arise sporadically, but may be associated with tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder characterized by germline mutations in the TSC1 or TSC2 genes. However, PEComas have previously been reported in five patients with Li-Fraumeni syndrome (LFS), which is an inherited cancer susceptibility disorder resulting from germline mutations in the TP53 tumor suppressor gene.

CASE PRESENTATION

We report a 49-year-old female patient with hepatic EAML and pancreatic cancer. Because she had previously been diagnosed with bilateral breast cancer at the age of 30, we performed a comprehensive genetic analysis to identify genetic alterations associated with any cancer predisposition syndrome. Whole-exome sequencing of a blood sample identified a heterozygous germline variant of TP53 (NM_000546.5):c.708C>A, and targeted next-generation sequencing of liver EAML and pancreatic cancer tissue samples demonstrated the same TP53 (NM_000546.5):c.708C>A variant in both. This, plus the patient's history of early-onset breast cancer, met the 2015 version of the Chompret criteria for diagnosis of LFS.

CONCLUSIONS

There have been very few case reports regarding the presence of PEComa in LFS, and to the best of our knowledge, this is the first report of EAML of the liver in a patient with LFS.

Very Rare Liver Tumor: PEComa Case Report with and a Review of Literature

Perivascular epithelioid cell tumors (PEComas) are very rare mesenchymal tumors. In addition to being rare in general, they are even rarer in the liver. There are various subtypes and there is only one case of liver PEComa reported in the clear cell type in the literature to date. We present the second clear cell type liver PEComa in this case by reviewing the literature data. The hypodense, smooth-edged, ovoid lesion was detected on computed tomography (CT) for performing abdominal pain in a 41-year-old female patient. Magnetic resonance imaging (MRI) was then performed for lesion characterization. The lesion was hypointense on T1-weighted imaging (T1WI), hyperintense on T2-weighted imaging (T2WI). In dynamic phases, it showed marked enhancement on the arterial phase and capsular enhancement with central washout on the portal and late venous phases. The posterior branch of the right portal vein extended into the mass. The lesion was excised and the pathological result was epithelioid clear cell subtype of PEComa. Although the imaging findings are generally nonspecific and certain diagnosis is made histopathologically, radiologists should consider PEComa in the differential diagnosis in the presence of intensely enhanced lesion on the right lobe in female patients. Also, the "large vessel sign" may help in the diagnosis.

Pancreatic PEComa, a not so uncommon neoplasm? Systematic review and therapeutic update

Pancreatic PEComas are extremely rare neoplasms with malignant potential, which mostly affect middle-aged women and are characterized by presenting melanocytic and myogenic markers in immunohistochemical analysis. There are no symptoms or pathognomonic imaging tests, so the diagnosis is established with the analysis of the surgical specimen or the FNA obtained with preoperative endoscopic ultrasound. The mean treatment consists on radical excision, adapting the intervention to the location of the tumor. To date, 34 cases have been described; however, more than 80% of them have been reported in the last decade, which suggests that it is a more frequent pathology than expected. A new case of pancreatic PEComa is reported and a systematic review of the literature is carried out according to the PRISMA guidelines with the aim of divulge this pathology, deepening its knowledge and updating its management.

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.

Perivascular Epitheloid Cell Tumor (PEComa) of the Neck

Perivascular epitheloid cell tumors (PEComas) are a family of neoplasms with distinctive perivascular epitheloid cells. 36 year old female patient admitted to our clinic with a mass on neck. Biopsy was reported as PEComa. PEComas are very rare, especially in neck region. Here, we present the second case in literature.

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

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

Recurrence of Pigmented Epithelioid Angiomyolipoma of the Kidney With Xp11 Translocation: A Case Report

This case report pertains to a 70-year-old male patient with a medical history marked by atrial fibrillation, ankylosing spondylitis, and Crohn's disease. Eight years prior, the patient underwent a left radical nephrectomy due to the presence of a pigmented epithelioid angiomyolipoma (PEComa) in the kidney. Notably, pathological examination revealed an unusual subtype of PEComa characterized by Xp11 gene translocation, indicating a more aggressive clinical profile. Following a five-year observation period without recurrence, the patient was discharged. However, eight years after initial treatment, he presented with vague symptoms of left loin discomfort and fullness, which had persisted for several weeks. Subsequent evaluation via computed tomography (CT) scanning showed a small lesion at the site of the renal bed. Surgical resection confirmed the return of the identical tumour. Key clinical points elucidated by this case include the varied behaviour of PEComas, the essential need for prolonged surveillance, and a recognition that recurrences can transpire even after extended disease-free intervals. Prior studies suggest recurrence rates of up to 31.8% for this specific PEComa subtype, emphasising the requirement for prolonged follow-up protocols.

Malignant lung PEComa (clear cell tumor): rare case report and literature review

Clear cell tumors of the lung (CCTL), or "sugar tumors" of lung, are very uncommon lesions and are mostly benign perivascular epithelioid cell (PEC) tumors with no specific morphologic features. Fewer than 100 cases have been reported; the aggressive nature demonstrated in sporadic reports has rarely been described in the literature. Although the course is generally described as benign, eight reported cases showed malignant behavior. We report a case of a PEC with a malignant presentation in a young man, correlating the main characteristics of the tumor with other cases reported in the literature to better elucidate this rare presentation. We also performed a literature review of reports on benign and malignant CCTL cases, with a focus on clinical, imaging, and immunohistochemical differentiation. CCTLs are rare tumors that require histopathological and immunohistochemical confirmation; to date, criteria that can predict malignant evolution are lacking.

Renal angiomyolipoma with tumor thrombi: Clinical analysis of 18 cases in a single-center experience

PURPOSE

To improve understanding of the clinical features of renal angiomyolipoma (AML) accompanied by tumor thrombus (TT).

METHODS

From January 2017 to February 2022, 18 patients with AML and TT were enrolled. We retrospectively analyzed them and there were 6 cases of epithelial AML (EAML) and 12 of classical AML (CAML). We compared the key variables between the two cohorts.

RESULTS

The mean age of the 18 cases was 42.0 (standard deviation [SD] 13.4) years and 14 (77.8%) were female. Eleven (61.1%) tumors were on the right side. Only two (11.1%) cases presented with flank pain. The mean follow-up time was 33.6 (IQR: 20.1-48.5) months. All participants were alive at the end of follow-up. One case developed lung metastases 21 months after operation but entered remission after 2 years of everolimus treatment. The imaging diagnoses of all CAML cases were consistent with the pathology, while all imaged EAML cases were diagnosed with carcinomas. Five EAML cases, but only one CAML case, exhibited necrosis (83.3 vs. 8.3%, P = 0.001). The Ki-67 index of the EAML group was significantly higher than that of the CAML group (7 vs. 2, P = 0.004).

CONCLUSIONS

Compared to CAML, EAML tended to be associated with a higher imaging misdiagnosis rate, and was more commonly associated with necrosis and a higher Ki-67 index. Surgery remains the prime treatment for nonmetastatic AML with TT; such cases have a relatively good prognosis despite the malignant potential.

Contrasting Outcomes in Two Cases of Uterine PEComa

Perivascular epithelioid cell tumours of the uterus are rare neoplasms with only few cases described in the literature. Ongoing contribution to the literature is important in order to understand the natural history for the diagnosis and management challenges for PEComa. We present two contrasting cases of PEComa who presented with postmenopausal bleeding, were diagnosed on endometrial biopsy and had surgical treatment. The first patient following treatment has been disease free for four years while on regular follow-ups. The second patient had aggressive disease developed early recurrence requiring chemotherapy and died in 17 months from diagnosis.

PEComa is a rare tumour with usually good outcomes, where surgery itself is adequate treatment. There is not much evidence available currently on the use of chemotherapy in rare cases, such as our second case, where PEComa presents aggressively. In this article, we elaborate two cases of contrasting outcomes with one presentation being aggressive requiring chemotherapy. We evaluated the current evidence on use of chemotherapy in rare cases.

A rare metastatic mesenteric malignant PEComa with TSC2 mutation treated with palliative surgical resection and nab-sirolimus: a case report

BACKGROUND

Malignant perivascular epithelioid cell tumors (PEComas) are exceedingly rare malignant mesenchymal neoplasms with characteristic morphological and immunohistochemical (IHC) patterns. However, some malignant PEComas are poorly differentiated with atypical histopathological features, making a definitive diagnosis difficult. PEComas are most commonly found in females and often show either TSC1 or TSC2 alterations, which result in the activation of the mTOR pathway, or TFE3 fusions. Given these molecular characteristics, mTOR inhibitors have recently been approved by the FDA in the treatment of malignant PEComas, particularly in those with TSC1/2 alterations. Therefore, molecular analyses may be helpful for both the diagnostic workup of and predicting response to mTOR inhibitors in cases of malignant PEComas.

CASE PRESENTATION

Here, we report a case of an aggressive, 23 cm mesenteric malignant PEComa with multiple peritoneal metastases in a young male patient. Pathological examination of the initial biopsy showed a malignant epithelioid neoplasm with high-grade morphology and atypical immunoprofile, which precluded a definitive diagnosis. Because of the patient's excessive transfusion requirements due to intra-tumoral hemorrhage, a palliative R2 resection was performed. Histopathological examination of the tumor revealed focal immunoreactivity for Melan-A, HMB-45, desmin, and CD117. Although a diagnosis of malignant PEComa was favored, other entities such as epithelioid gastrointestinal stromal tumor (GIST) or melanoma could not be definitively ruled out. Given the favored diagnosis, the patient was started on sirolimus, an mTOR inhibitor, rather than chemotherapy. Molecular analyses were performed and the tumor was found to harbor mutations in TP53 and TSC2, supporting a definitive diagnosis of malignant PEComa. The patient was then switched to nab-sirolimus, with initial stabilization of the disease.

CONCLUSIONS

This report details a multidisciplinary approach for the diagnosis and management of a highly aggressive, metastatic malignant PEComa in a young male patient. The basis for the treatment of malignant PEComas with the recently FDA-approved mTOR inhibitor, nab-sirolimus, is also reviewed. In summary, this case highlights the importance of molecular analysis, particularly TSC1/2 alterations, for both the definitive diagnosis of malignant PEComas and predicting their response to nab-sirolimus.

Hepatic perivascular epithelioid cell tumor (PEComa): contrast-enhanced ultrasound (CEUS) characteristics-a case report and literature review

Perivascular epithelioid cell tumors (PEComa) are rare mesenchymal neoplasms that arise from soft tissue of various organs such as the stomach, intestines, and lungs. We report a rare case of a primary PEComa of the liver and its characteristics on contrast-enhanced ultrasound (CEUS) in a 51-year-old female patient with an incidental finding of a hypoechoic liver lesion with peripheral hypervascularization on Doppler ultrasound. CEUS showed homogenous hypervascularity in the arterial phase that was consistent in the portal phase. In the late phase, a central washout phenomenon was evident. Histopathologic findings on sonographic biopsy of the lesion revealed a mesenchymal tumor with positivity for melanocytic markers Human Melanin Black-45 (HMB45) and Melan-A consistent with a PEComa. Despite the absence of high-risk features for malignancy, surgical resection was recommended due to the uncertain malignant potential of PEComas. The patient refused the operation and preferred sonographic follow-up; the lesion was stable over a period of 2 years. CEUS can provide valuable information regarding PEComa. After histological confirmation, the choice between resection and a watchful waiting must be made on individual basis.

Targeted therapies for the treatment of soft tissue sarcoma

Soft tissue sarcomas are rare malignant tumors derived from mesenchymal cells that have a high morbidity and mortality related to frequent occurrence of advanced and metastatic disease. Over the past two decades there have been significant advances in the use of targeted therapies for the treatment of soft tissue sarcoma. The ability to study various cellular markers and pathways related to sarcomagenesis has led to the creation and approval of multiple novel therapies. Herein, we describe the current landscape of targeted medications used in the management of advanced or metastatic soft tissue sarcomas, excluding GIST. We distinguish three categories: targeted therapies that have current US Food and Drug Administration (FDA) approval for treatment of soft tissue sarcoma, non-FDA approved targeted therapies, and medications in development for treatment of patients with soft tissue sarcoma.

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

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

Hepatic Perivascular Epithelioid Cell Tumor Mimicking Hepatocellular Carcinoma

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms, and liver PEComas are extremely rare. They are usually discovered incidentally, and diagnostic pitfalls are frequent owing to similar imaging characteristics to other liver neoplasms. We present a patient whose evaluation was consistent with a right-sided hepatocellular carcinoma for which right hepatectomy was performed. Based on the final histopathological examination and immunohistochemistry, a diagnosis of PEComa was made. Immunohistochemistry plays a crucial role in arriving at the diagnosis, and resection represents the standard of care. A long-term follow-up is recommended because the natural history of PEComas is unpredictable.

Case Report: Perivascular epithelioid tumors of the gastrointestinal tract

Background

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

Case presentation

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

Conclusion

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

Angiomyolipoma of the kidney-Clinicopathological analysis of 52 cases

The renal angiomyolipoma (AML) is a benign tumor characteristically composed of fat, smooth muscle tissue, and vessels. We collected AMLs from our nephrectomy database, reclassified them according to their histological appearance, recorded the demographic, clinical, and pathological parameters, and compared them with oncocytoma (RO) and renal cell carcinoma (RCC). Immunohistochemistry was ordered in 41 cases. In 2224 nephrectomies, we found 52 AMLs with a 53 mm median size. The mean age was 52.76. Forty-eight tumors were sporadic, while four were hereditary. The revision resulted in 31 classic, 13 leiomyoma-like, five lipoma-like, two epithelioid, and one AML with epithelial cysts. SMA was diffusely positive, except for the epithelioid type, while MelanA harbored stronger expression than HMB45. AML was more frequent in females and appeared ten and 7 years earlier than RO and RCC, respectively. The follow-up time was 7.42 years, and neither tumor-related death nor relapse occurred. AML is rare in nephrectomies and develops primarily in females in their 50s with an average size of 50-60 mm at the surgery. The histological appearance in order of frequency is classic, leiomyoma-like, lipoma-like, epithelioid, and cystic. The MelanA, HMB45, and SMA immunohistochemistry can support the light-microscopic findings.

Orbital Perivascular Epithelioid Cell Tumor in a Case of Tuberous Sclerosis

The aim of the study was to report a case of orbital perivascular epithelioid cell tumor (PEComa) in a known diagnosed patient of tuberous sclerosis and retinal astrocytic hamartoma. 43-year-old female presented with rapid progressive painful proptosis in the left eye, also reported new mass growing in her upper back. The patient past medical history is significant for left renal angiomyolipoma and multiple bilateral lung cysts of which she underwent right nephrectomy and lung biopsy, respectively. The lung biopsy turned diagnostic for lymphangiomyomatosis. On external examination, the left eye was grossly proptotic with hypoglobus. A typical butterfly distribution of sebaceous adenoma was noted across the patient cheeks and nose. Visual acuity in the right eye was 20/20 and the left eye, 20/25. Funduscopic examination identified type 1, 2, and 3 retinal astrocytic hamartomas. MRI brain and orbit was significant for a lesion arising from the lateral orbital wall with extensive bone destruction, displacing the left optic nerve medially. CT chest showed left extrathoracic mass had same radiological features as the orbital lesion; thus, an incisional biopsy performed on the former was diagnostic for PEComa with atypical features. This is the first observed case of PEComa in a known diagnosed patent with TS and retinal astrocytic hamartoma. The association of tuberous sclerosis complex and orbital PEComa is rarely and poorly reported in the literature compared to extraocular PEComa.

Rapidly Progressive Malignant Pelvic Perivascular Epithelioid Cell Neoplasm (PEComa) Associated with Eggerthella lenta Bloodstream Infection

Perivascular epithelioid cell tumors (PEComa) are rare mesenchymal neoplasms composed of cells that express melanocytic and myogenic markers and grow around small blood vessels. PEComa often show benign behaviors but can also be highly aggressive. In frail and more complex patients, many conditions can overlap, compounding the diagnostic and therapeutic difficulties inherent in rare diseases. Moreover, the complexity of modern patients introduces new and significant players in host-microbe interactions, and emerging pathogens represent a relevant challenge to modern healthcare. Among these pathogens is Eggerthella lenta, an anaerobic gram-positive bacterium of the normal gut microbiota associated with life-threatening infections. Here, we present a case of malignant pelvic PEComa with rapid metastatic progression in a 73-year-old man who presented with an E. lenta bloodstream infection. Approaching differential diagnosis with open-mindedness may assist in better imaging interpretation, surgery scheduling, and proper treatment planning. The non-specific clinical presentation might delay timely diagnosis, while the absence of well-consolidated guidelines undermines the accurate management of the disease, for which strict follow-up can favor better outcomes. Progress in diagnostic techniques, such as the implementation of MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) mass spectrometry for micro-organism identification, helps with a more accurate pathogen diagnosis and characterization. This allows the implementation of the most appropriate therapy, as well as better surveillance of antibiotic resistance, infection prevention, and control measures. Nevertheless, a good dose of wisdom is vital to avoid overlooking potentially harmful pathogens, particularly in frail individuals.

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

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

Case report: Kidney perivascular epithelioid cell tumor treated with anti-VEGFR tyrosine kinase inhibitor and MTOR inhibitor

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal tumors arising from perivascular epithelial cells. There was no standard treatment for unresectable PEComa before 2021. For a low incidence and a rarely curable disease, development of new therapy is essential. A 45-year-old female was diagnosed with malignant renal PEComa (likely with TFE3 rearrangement) that underwent rapid progression after 10 months of surgery. The patient then received the tyrosine kinase inhibitor (TKI) Apatinib, and the tumor remained stable for 15 months before another progression. The patient then received the MTOR inhibitor everolimus that alleviated her symptoms but the tumor went into remission again after another 15 months. This result suggests that antagonizing the vascular endothelial growth factor receptor (VEGFR) pathway be a useful strategy for malignant PEComas, along with the MTOR pathway inhibition that had recently been approved for the rare tumor.

Primary retroperitoneal PEComa: an incidental finding

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

Specific imaging features indicate the clinical features of patients with hepatic perivascular epithelioid cell tumor by comparative analysis of CT and ultrasound imaging

Objective

The objective of the study was to explore the CT and ultrasound features and clinical significance of perivascular epithelioid cell tumor (PEComa) of the liver.

Methods

Eleven hepatic PEComa patients treated in our hospital were retrospectively analyzed based on the characteristics of the imaging results of the patients, including conventional ultrasound, CDFI, contrast-enhanced ultrasound (CEUS), and contrast-enhanced CT (CECT).

Results

CT scans showed that all lesions were hypodense. Ultrasonography showed that lesions were either hyperechoic (4/11, 36.36%), hypoechoic (4/11, 36.36%), isoechoic (1/11, 9.09%), or heterogeneously echoic (2/11, 18.18%). CDFI showed that most of the lesions had an abundant blood supply (9/11, 81.82%). Whether on CT scan or ultrasonography, the margins of the lesions were dominated by clear margins. Ultrasonography revealed more features: hyperechoic patterns around lesions (3/11, 27.27%) and lateral shadow (5/11, 45.45%). The CDFI showed that large blood vessels were observed around the lesions (9/11, 81.82%). CECT shows two enhancement patterns: “fast in and fast out (FIFO)” (8/11, 72.72%) and “fast in and slow out (FISO)” (3/11, 27.27%). CEUS shows that all lesions had the enhancement pattern of “FISO,” which was different from CECT. All lesions displayed rapid enhancement during HAP in CEUS during 7–20 s. Four patients (36.36%) washed out at 60–180 s, another four (36.36%) washed out at 180–300 s, and the remaining three patients (27.27%) showed no signs of washout even at 360 s.

Conclusion

Some imaging features, such as clear margins, peripheral hyperechoic around the lesion, lateral shadow, the large blood vessels around lesions, and the “FISO” enhancement pattern, may indicate expansive growth of the tumor and be helpful in the diagnosis of PEComa. Ultrasound images may provide more details for clinical reference.

Cutaneous Angiomyolipoma-A Distinct Entity That Should Be Separated From Classic Angiomyolipoma: Complete Review of Existing Cases and Defining Fundamental Features

Cutaneous angiomyolipoma is a rare mesenchymal tumor that is demographically, clinically, and immunohistochemically distinct from its renal and extrarenal counterparts. We present a case of cutaneous angiomyolipoma in the right retroauricular area of a 35-year-old male patient and provide a broad systematic review of the literature and the largest compilation of cutaneous angiomyolipomas reported to date. According to the findings presented in this review, we conclude that cutaneous angiomyolipoma should be completely separated from renal and extrarenal angiomyolipomas and therefore be considered a distinct entity in the classification of skin tumors.

Perivascular Epithelioid Cell Tumor (PEComa) of the Lung in a 56-Year-Old Female Patient: A Case Report

Perivascular epithelioid cell tumors, best known as PEComas, are extremely uncommon mesenchymal tumors The etiology of PEComas remains unestablished and its clinical presentation is usually benign. PEComas lack a distinctive symptomatic presentation; thus, the diagnosis of these tumors relies mainly on pathological examinations. These neoplasms have a very distinct immunoreactivity for melanocytic markers critical for their identification. Due to the rarity of these tumors and lack of a distinct disease presentation, we discuss the diagnostic relevance of imaging and pathologic findings in a 56-year-old woman diagnosed with a PEComa in the right middle lobe of the lung.

Updates in Pathology for Retroperitoneal Soft Tissue Sarcoma

Retroperitoneal tumors are extremely rare. More than 70% of primary retroperitoneal soft tissue tumors are malignant. The most common sarcomas in the retroperitoneum include liposarcomas and leiomyosarcoma, however other sarcomas, along with benign mesenchymal tumors, can occur. Sarcomas are a heterogenous group of tumors with overlapping microscopic features, posing a diagnostic challenge for the pathologist. Correct tumor classification has become important for prognostication and the evolving targeted therapies for sarcoma subtypes. In this review, the pathology of retroperitoneal soft tissue sarcomas is discussed, which is important to the surgical oncologist. In addition, less common sarcomas and benign mesenchymal tumors of the retroperitoneum, which may mimic sarcoma clinically and pathologically, are also discussed.

Perivascular epithelioid cell tumour-mimicking retroperitoneal leiomyosarcoma

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

Pitfalls in the diagnosis and treatment of fat-poor angiomyolipoma of the renal pelvis mimicking urothelial carcinoma: report of three rare cases

Angiomyolipoma (AML) represents the most frequent benign neoplasm of the kidney. It arises mostly in the cortex and protrudes into the perirenal space. It is extremely rare for a fat-poor AML to originate from the renal sinus, invade the pelvis, and present with hematuria. Because of the rarity of this lesion, differentiating it from a urothelial carcinoma is difficult, thereby making a preoperative diagnosis and management complex and challenging. We report three cases of fat-poor AML centered within the renal pelvis mimicking a urothelial carcinoma that underwent radical nephroureterectomy. The clinical characteristics, surgical management, and prognosis are discussed to achieve better preoperative evaluation of these entities. This is the first report of fat-poor AMLs involving the renal pelvis and presenting with hematuria. Nephron-sparing treatment is crucial for patients with these entities. Accurate diagnosis may allow partial resection or kidney-preserving treatment.

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 review of 99mTc-sestamibi SPECT/CT for renal oncocytomas: A modified diagnostic algorithm

99mTc-sestamibi SPECT/CT is a promising nuclear medicine imaging investigation for benign renal lesions such as renal oncocytomas. The purpose of this article is to i) review the current literature on 99mTc-sestamibi SPECT/CT, ii) to review to current application of 99mTc-sestamibi SPECT/CT for indeterminate renal lesion imaging, and iii) to discuss present limitations and areas for future research. The literature has been reviewed up to April 2022 for articles relating to the application of 99mTc-sestamibi SPECT/CT for benign renal lesions including a recently published systematic review and meta-analysis performed by the authors. One study evaluating 99mTc-sestamibi SPECT alone and five studies evaluating 99mTc-sestamibi SPECT/CT have been performed to date. 99mTc-sestamibi SPECT/CT demonstrates high sensitivity and specificity for detecting benign renal lesions, particularly renal oncocytomas. 99mTc-sestamibi SPECT/CT demonstrates near-perfect specificity for benign and low-grade renal lesions. The optimal quantified threshold ratio for tumor-to-background renal parenchyma radiotracer uptake for a positive result is > 0.6. In this article, we propose a modified diagnostic algorithm for small enhancing renal masses measuring 1-4 cm in which suspected benign lesions after conventional imaging are considered for 99mTc-sestamibi SPECT-CT. In this algorithm, positive studies can be monitored with active surveillance rather than requiring invasive biopsy and/or targeted therapy.

Polycythemia Rubra Vera and Sporadic Bilateral Renal Angiomyolipomas: A Case Report

Polycythemia rubra vera (PRV) is a clonal myeloproliferative neoplasm characterized by autonomous production of erythrocytes, neutrophils, and platelets. Angiomyolipomas (AMLs) are benign renal perivascular epithelioid cell neoplasms of which approximately 80% are sporadic. Here, we report synchronous diagnoses of PRV and asymptomatic sporadic bilateral renal AMLs in a 71-year-old woman. We describe her treatment with phlebotomy and hydroxyurea for PRV and surveillance for renal AMLs. We compare the features and treatment of the present case with those of two previously reported women who also had PRV and sporadic renal AMLs. Finally, we discuss the management and acquired genetic basis of both neoplasms.

Fibroma-like PEComa: a newly recognized soft tissue neoplasm in tuberous sclerosis patients-imaging features and review of literature

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of spindled to epithelioid cells that co-express both melanocytic and myogenic markers. Recently, in 2018, a distinctive variant of PEComa has been described that arises in association with tuberous sclerosis complex (TSC) and resembles a fibroma by conventional morphology (called fibroma-like PEComa). Herein, we describe a case of a fibroma-like PEComa in a 4-year-old male child with a known diagnosis of tuberous sclerosis who presented with a firm mass along the anteromedial aspect of the right knee. The mass was excised, and microscopic examination showed bland spindled to stellate cells embedded in a dense collagenous stroma, morphologically resembling a fibroma. Immunohistochemistry analysis showed positivity for desmin (a myogenic marker) and HMB45 (a melanocytic marker), a hallmark for PEComas. To our knowledge, only six cases of fibroma-like PEComa have been described in the literature so far and this is the first report of such a tumor in the medial retinaculum of the knee joint with illustrations of conventional and diffusion imaging features. This case highlights the unique association of fibroma-like PEComa lesions with TSC. This should be considered a differential diagnosis for T2 hypointense masses in tuberous sclerosis patients. In addition, a diagnosis of fibroma-like PEComa should prompt further evaluation for associated TSC.

Tuberous sclerosis complex: a complex case

Tuberous sclerosis complex (TSC) is an inheritable disorder characterized by the formation of benign yet disorganized tumors in multiple organ systems. Germline mutations in the TSC1 (hamartin) or more frequently TSC2 (tuberin) genes are causative for TSC. The malignant manifestations of TSC, pulmonary lymphangioleiomyomatosis (LAM) and renal angiomyolipoma (AML), may also occur as independent sporadic perivascular epithelial cell tumor (PEComa) characterized by somatic TSC2 mutations. Thus, discerning TSC from the copresentation of sporadic LAM and sporadic AML may be obscured in TSC patients lacking additional features. In this report, we present a case study on a single patient initially reported to have sporadic LAM and a mucinous duodenal adenocarcinoma deficient in DNA mismatch repair proteins. Moreover, the patient had a history of Wilms' tumor, which was reclassified as AML following the LAM diagnosis. Therefore, we investigated the origins and relatedness of these tumors. Using germline whole-genome sequencing, we identified a premature truncation in one of the patient's TSC2 alleles. Using immunohistochemistry, loss of tuberin expression was observed in AML and LAM tissue. However, no evidence of a somatic loss of heterozygosity or DNA methylation epimutations was observed at the TSC2 locus, suggesting alternate mechanisms may contribute to loss of the tumor suppressor protein. In the mucinous duodenal adenocarcinoma, no causative mutations were found in the DNA mismatch repair genes MLH1, MSH2, MSH6, or PMS2 Rather, clonal deconvolution analyses were used to identify mutations contributing to pathogenesis. This report highlights both the utility of using multiple sequencing techniques and the complexity of interpreting the data in a clinical context.

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

BACKGROUND AND AIMS

Perivascular epithelioid cell neoplasms (PEComas) are a rare type of mesenchymal neoplasm and their preoperative diagnosis is challenging. In this study, we summarized the experience from a single medical center to study the examinations, clinical presentations, and pathological and histological characteristics of PEComas in the liver in order to optimize overall understanding of the diagnosis and treatment of these neoplasms.

METHODS

We conducted a retrospective analysis to investigate the clinical and pathological characteristics as well as imaging presentations of 75 patients diagnosed with hepatic PEComa in The First Affiliated Hospital of Zhejiang University between April 2010 and April 2020.

RESULTS

Among the 75 patients, 52 were women, and the median age was 48 years. Most patients had no specific symptoms, and two were admitted to the hospital for a second time owing to relapse. All patients underwent surgical resection. Histologically, 38 patients had classical angiomyolipoma (AML) and 37 had epithelioid AML. The PEComas were accompanied by positive immunohistochemical expression of HMB45, Melan-A, and smooth muscle actin. Follow-up data were obtained from 47 of the total 75 patients, through October 2020. Two patients had metastasis after surgery.

CONCLUSIONS

AML is the most common type of hepatic PEComa. There are no specific symptoms of hepatic PEComa, and serological examinations and imaging modalities for accurate preoperative diagnosis are lacking. Epithelioid AML should be considered a tumor of uncertain malignant potential; however, the prognosis of PEComa after resection is promising.

[CME-Sonography 104: Angiomyolipomas]

CME-Sonography 104: Angiomyolipomas Abstract. Angiomyolipomas are the most common benign kidney tumors. Approximately 80 % are spontaneously occurring tumors, the majority <1.0 cm (approximately 54 %). These tumors do not grow and are harmless. Tumors between 1.0 and 2.5 cm (approx. 44 %) also very rarely grow and remain harmless. Larger tumors are rarely found (about 2 %). These must be carefully monitored, as tumors >4.0 cm can spontaneously manifest dangerous bleeding. Apart from spontaneous occurrence, there are also angiomyolipomas in the context of the tuberous sclerosis complex (TCS). Such tumors are often larger and combined with renal cysts and renal cell carcinomas. Measuring the of echo intensity is important for diagnosis.

A case of caecal “PECOMA”: An uncommon entity

Introduction and importance

World Health Organization (WHO) defines PEComa as a mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. The symptoms and clinical signs of PEComa patients are nonspecific. Hence, diagnosis is usually difficult. Since it's a rare diagnosis, further research might help in understanding the disease better.

Case presentation

The patient in this study was an asymptomatic patient, who did colonoscopy as part of a regular check-up. A submucosal cecal tumor was detected in colonoscopy, and apart from that, all other investigative parameters were within normal limits.

Clinical discussion

Laparoscopic Ileocecectomy was performed, and the histopathology report was suggestive of Pecomatosis (PEComa – Perivascular epithelioid cell tumor). The PEComas, neoplasms with perivascular epithelioid cell differentiation, are mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells (PEC). The characteristic features of PEC are the positivity of melanocytic markers and smooth muscle markers.

Conclusion

Perivascular epithelioid tumors are mostly rare in the gastrointestinal tract, and even more unusual to be detected in Cecum. Surgery is the mainstay of the treatment, although, adjuvant therapy has been tried in recent times. The patients have to be kept in close follow-up, as there are reported cases of recurrences and distant metastasis.

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By WHO, PEComa is “mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells”

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The PEComas affecting GI tract are classified under PEComas-not otherwise specified (PEComa-NOS) type

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The PEComas can usually take both benign and malignant course

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Immunohistochemical stains of specimen showed positive in actin(SMA), HMB45, and vimentin S-100 showed negative.

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Surgical management and close follow-up are warranted in every case of PEComa.

Rare case of angiomyolipoma of the larynx

We report a rare case of angiomyolipoma (AML) of the larynx. AML belongs to the family of perivascular epithelioid cell tumors (PEComas). We review the literature on PEComas and describe differences in immunohistochemical findings between renal AML and AML in the head and neck region.

Epithelioid angiomyolipoma: a pathological entity discovered in Verona with the endorsement of Doctor Rosai

In this manuscript, we summarize the main features of angiomyolipoma highlighting the recognition of epithelioid angiomyolipoma and the discovery of immunohistochemical expression of HMB45 in a group of tumors that now are referred to as as PEComas. In this scenario, Dr. Rosai believed in our intuition, demonstrating his intellectual honesty and motivated us with his experience (“when a tumor seems malignant it is malignant”) and enthusiasm for the new entities (“in Verona, you use HMB45 instead of H&E”). He really pushed the improvement of the knowledge in this field.

nab-Sirolimus for Patients With Malignant Perivascular Epithelioid Cell Tumors

PURPOSE

Malignant perivascular epithelioid cell tumor (PEComa) is a rare aggressive sarcoma, with no approved treatment. To our knowledge, this phase II, single-arm, registration trial is the first prospective clinical trial in this disease, investigating the safety and efficacy of the mammalian target of rapamycin inhibitor nab-sirolimus (AMPECT, NCT02494570).

PATIENTS AND METHODS

Patients with malignant PEComa were treated with nab-sirolimus 100 mg/m2 intravenously once weekly for 2 weeks in 3-week cycles. The primary end point was objective response rate evaluated by independent radiology review. Key secondary end points included duration of response, progression-free survival, and safety. A key exploratory end point was tumor biomarker analysis.

RESULTS

Thirty-four patients were treated (safety evaluable), and 31 were evaluable for efficacy. The overall response rate was 39% (12 of 31; 95% CI, 22 to 58) with one complete and 11 partial responses, 52% (16 of 31) of patients had stable disease, and 10% (3 of 31) had progressive disease. Responses were of rapid onset (67% by week 6) and durable. Median duration of response was not reached after a median follow-up for response of 2.5 years, with 7 of 12 responders with treatment ongoing (range, 5.6-47.2+ months). Twenty-five of 31 patients had tumor mutation profiling: 8 of 9 (89%) patients with a TSC2 mutation achieved a confirmed response versus 2 of 16 (13%) without TSC2 mutation (P < .001). The median progression-free survival was 10.6 months (95% CI, 5.5 months to not reached), and the median overall survival was 40.8 months (95% CI, 22.2 months to not reached). Most treatment-related adverse events were grade 1 or 2 and were manageable for long-term treatment. No grade ≥ 4 treatment-related events occurred.

CONCLUSION

nab-Sirolimus is active in patients with malignant PEComa. The response rate, durability of response, disease control rate, and safety profile support that nab-sirolimus represents an important new treatment option for this disease.

Case Report: A Rare Case of a Ventricular Perivascular Epithelioid Cell Tumor With Histologic Characteristics That Resembled a Primary Cardiac Rhabdomyoma

We present the case of a young male patient with an initial diagnosis of a rhabdomyoma that was surgically treated at a different hospital when he was 17. After a 2-year disease-free period, the patient presented another intra-cardiac mass. He refused surgical treatment and died 5 years later. Post-mortem immunochemistry studies of both tumors led to the diagnosis of a primary malignant cardiac PEComa with histopathologic characteristics that resembled a rhabdomyoma with abundant “spider cells.”

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.

Malignant perivascular epithelioid cell neoplasm in the liver: report of a pediatric case

Background

Perivascular epithelioid cell neoplasm (PEComa) in a child is very rare. We herein report the first malignant case of PEComa developing in the liver of a pediatric patient.

Case presentation

A 10-year-old boy visited a private clinic with prolonged fever of unknown etiology. Abdominal ultrasonography was performed to evaluate the fever’s origin, revealing a large tumor in the liver. He was thus referred to a nearby hospital to investigate the tumor further. Enhanced computed tomography (CT) showed a 6.8 × 5.9 × 10.5-cm solid lesion on S4 and S5. On magnetic resonance imaging (MRI), the tumor had a low signal intensity on T1 imaging and high signal intensity on T2 imaging, with partial diffusion restriction. ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) showed a marked uptake in the mass lesion with no evidence of metastasis. The patient was negative for all tumor markers, including AFP, CEA and PIVKA-II. The results of a needle biopsy suggested hepatocellular carcinoma. The tumor’s rapid growth suggested malignancy. Hepatic segmentectomy (S4 + S5 + S8) was performed. The tumor was resected en bloc with a margin. Microscopically, the tumor showed atypical spindle, polygonal or oval-shaped cells with a high nuclear grade, and vascular invasion. Immunohistochemistry was positive for alpha-smooth muscle antigen (α-SMA), human melanin black-45 (HMB-45) and melan A. The pathological diagnosis was malignant PEComa. In the 6 months after surgery, the patient complained of shoulder pain. MRI showed a dumbbell-shaped tumor at the 2nd thoracic vertebrae, which was confirmed to be bone metastasis of PEComa. After chemotherapy, including ifosfamide and doxorubicin, vertebrectomy was performed. Two years later, thoracoabdominal CT showed a 10-cm solid mass occupying the pelvis and a 15-mm nodule in the middle lobe of the right lung. Under a diagnosis of peritoneal and lung metastases, they were surgically removed and metastasis of PEComa was pathologically confirmed. Four months after the 2nd relapse, pelvic metastasis appeared again and mTOR (mammalian target of rapamycin) inhibitor was initiated. To our knowledge, this is the first report of malignant hepatic PEComa in a pediatric patient.

Conclusion

Although extremely rare, malignant hepatic PEComa can develop in a child.

Tuberous Sclerosis: Current Update

Tuberous sclerosis complex (TSC) is a relatively rare autosomal dominant neurocutaneous disorder secondary to mutations in the TSC1 or TSC2 tumor suppressor genes. Although manifestation of the classic triad of seizures, intellectual disability, and facial angiofibromas may facilitate timely diagnosis of TSC, the multisystem features that may indicate TSC in the absence of these manifestations remain highly variable. In addition, patients with TSC are at risk of developing multiple benign and malignant tumors in various organ systems, resulting in increased morbidity and mortality. Thus, imaging plays a critical role in diagnosis, surveillance, and management of patients with TSC. It is crucial that radiologists be familiar with TSC and the various associated imaging features to avoid a delayed or incorrect diagnosis. Key manifestations include cortical dysplasias, subependymal nodules, subependymal giant cell astrocytomas, cardiac rhabdomyomas, lymphangioleiomyomatosis, and angiomyolipomas. Renal angiomyolipomas in particular can manifest with imaging features that mimic renal malignancy and pose a diagnostic dilemma. Other manifestations include dermatologic and ophthalmic manifestations, renal cysts, renal cell carcinomas, multifocal micronodular pneumocyte hyperplasia, splenic hamartomas, and other rare tumors such as perivascular epithelioid tumors. In addition to using imaging and clinical features to confirm the diagnosis, genetic testing can be performed. In this article, the molecular pathogenesis, clinical manifestations, and imaging features of TSC are reviewed. Current recommendations for management and surveillance of TSC are discussed as well. ^©RSNA, 2021.

Unusual paediatric sigmoid perivascular epithelioid cell tumour with regional lymph node metastasis treated using gemcitabine and docetaxel: a case report and literature review

Perivascular epithelioid cell tumour (PEComa) is an extremely rare neoplasm with distinctive morphology and specific expression of immunohistochemical markers. The lesion is typically diagnosed in middle-aged women, with few reports of paediatric cases, and there is no standardized treatment for the tumour type. Here, the case of a 17-year-old female, who presented with painless haematochezia for 2 days and was diagnosed with gastrointestinal PEComa of the sigmoid colon with regional lymph node metastasis after serial examination, is presented. She was treated by surgical resection of the tumour and cytotoxic chemotherapy comprising 900 mg/m² gemcitabine and 100 mg/m² docetaxel every 3 weeks for six cycles. Haematochezia did not recur, and complete response was achieved, with progression-free survival at the 24-month follow-up examination. Surgical resection with adjuvant conventional cytotoxic chemotherapy may be considered as an option for treating gastrointestinal PEComa.