Perivascular epithelioid cell tumors (PEComas) are a family of benign neoplasms characterized by smooth muscle and melanocytic differentiation. Orbital cases are rare. A 9-year-old male presented with a slowly growing orbital mass. Magnetic resonance imaging (MRI) revealed a well-defined orbital mass without intracranial extension. The microscopic appearance of the complete resection specimen showed large nests of epithelioid cells with wide cytoplasm containing melanin pigment and round to oval nuclei with mild cytonuclear atypia and low mitotic activity. Immunohistochemistry was positive for HMB45 and negative for melanA, smooth muscle actin, desmin and S-100 protein. Pangenomic RNA-sequencing identified an in-frame NONO-TFE3 rearrangement, and clustering data showed that the tumor\'s gene expression profile was grouped with other previously studied PEComas. A diagnosis of orbital pigmented PEComa with uncertain malignant potential associated with a NONO-TFE3 rearrangement was made. There was no recurrence after 1 year of follow-up.

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

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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.
METHODS: 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.

A 77-year-old female presented with a 6-month history of a 2-cm pink exophytic tumor on the right anterior shin, which had grown rapidly and began to bleed over the last 4 weeks. A shave biopsy showed a dermal proliferation of epithelioid spindled cells, arranged in nests and trabeculae associated with thin-walled capillary vessels. The cells showed pleomorphic nuclei with vacuolated nuclear chromatin and occasional prominent nucleoli. Mitotic figures (7/10 high-power fields [HPFs]), including atypical forms, were present in the specimen. Immunohistochemical staining was negative for SOX10 and stained positive for MiTF. The histopathologic findings were consistent with a malignant perivascular epithelioid cell tumor (PEComa). A malignant PEComa is a rare entity of mesenchymal-derived cells with both melanocytic and myocytic differentiation. A PEComa is considered to be malignant by fulfilling two of the following criteria: size greater than 5 cm, vascular invasion, necrosis, mitotic figures greater than 1 per 50 HPF, infiltrative growth pattern, high nuclear grade, and hypercellularity. PEComas show immunohistochemical positivity to myocytic markers such as SMA, pan-muscle actin, muscle myosin, calponin, and h-caldesmon as well as melanocytic markers such as HMB-45, Melan-A, tyrosinase, and MiTF.

The perivascular epithelioid cell tumor (PEComa) is a rare tumor of interstitial origin characterized by several immunological and muscle cell markers. The clear cell sugar tumor (CCST) of the lung is a type of PEComa defined by thin cell walls and high levels of glycogen in the cytoplasm. We herein reported the case of a 48-year-old male with a recurrence of lung CCST. The preoperative diagnosis of the lung mass was performed by percutaneous needle biopsy. During the thoracoscopic resection, multiple adhesions in the thoracic cavity were described. The tumor invaded the chest wall, and the boundaries between the tumor and surrounding normal tissues were unclear. The mediastinal lymph nodes were significantly enlarged. No relevant gene mutations were detected. After concomitant chemoradiotherapy, the patient\'s condition was stable. We also conducted a literature review and discussed the overall findings.

Perivascular epithelioid cell tumor (PEComa) is a rare type of mesenchymal neoplasm, which occurs most commonly in uterus and gastrointestinal tract. PEComa with perirenal manifestation is an extremely rare entity. To the best of our knowledge, only four cases have been reported up to now. In this case, we reported a patient with both a pulmonary mass and a perirenal mass. Two resections were performed successively and postoperative pathology suggested pulmonary micro invasive adenocarcinoma (MIA) and perirenal PEComa. This is the first case of perirenal PEComa with pulmonary MIA. Combining the present case and prior literature, we summarized the crucial role of immunohistochemistry in the diagnosis and consider that complete operation might be conducive to patients with perirenal PEComa that presents a benign phenotype, regardless of complications with other tumors.

Neoplasms with perivascular epithelioid cell differentiation (PEComas) of the pancreas are rare, and only 22 cases have been reported globally. Therefore, clinician and pathologist knowledge of this tumor\'s biologic behavior and molecular genetics has been limited. A 40-year-old female patient presented with a space-occupying mass in the pancreas found by abdominal B-mode ultrasonography upon physical examination. Laparoscopic resection of the pancreatic body and tail was performed, and a cystic-solid tumor of about 2 × 2 cm was identified. PEComa is a type of mesenchymal tumor with uncertain biologic behavior, more frequently found in females. PEComa features a unique histomorphology and immunophenotype. We summarize the characteristics and research progress of the pancreatic PEComa, which will be convenient for physicians and pathologists to fully understand the disease to avoid misdiagnosis and to provide a reference for treatment and prognosis.

Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor rarely described in the liver. Sonazoid is a new ultrasound contrast with both vascular and post-vascular phases due to the uptake of Kupffer cell. CD68 is a defined immunohistorical staining marker for macrophage including Kupffer cell. No previous cases have been reported to reveal Kupffer images in the post-vascular phase by using Sonazoid and pathologic characters of CD68 positive cell in PEComa. Herein, we describe the first case to present Sonazoid contrast-enhanced ultrasonography (CEUS) findings in Kupffer images and CD68 positive cell in hepatic PEComa which may lead to rethink of the phagocytic properties of macrophages.

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal tumors with malignant potential that arise from gynecological organs in up to 25% of cases. The lack of data regarding the preoperative US features of uterine PEComas is reflected by the frequent misdiagnosis with leiomyomas. We describe the sonographic appearance of a richly vascularized cervical PEComa mimicking a myoma and report the analysis of six additional cases in the literature with a description of their ultrasound features. Most cases involved a single lesion arising from the uterine cervix with a rapid growth pattern, regular margins, heterogeneous echogenicity, absence of shadowing, and moderate-to-rich vascularity.