Perivascular Epithelioid Cell Differentiation Research Articles

Sclerosing PEComa: Clinicopathologic Analysis of a Distinctive Variant With a Predilection for the Retroperitoneum

PEComas (tumors showing perivascular epithelioid cell differentiation) are a family of mesenchymal neoplasms that include angiomyolipoma, clear cell "sugar" tumor of the lung, lymphangiomyomatosis, and a group of uncommon lesions that arise in soft tissue, visceral organs, and skin. We describe a distinctive variant of PEComa that shows extensive stromal hyalinization, a feature not previously described in these tumors. Thirteen PEComas with extensive stromal hyalinization were identified from a total of 70 cases of PEComa received between 1996 and 2006 (19%). All patients were women, with a mean age of 49 years (range, 34 to 73y). One patient had tuberous sclerosis. Ten tumors (77%) arose in the retroperitoneum (8 pararenal), and 1 each in the pelvis, uterus, and abdominal wall. Median tumor size was 9.5 cm (range, 4.5 to 28 cm). All except 2 were grossly well-circumscribed. The tumors were composed of cords and trabeculae of cytologically uniform bland epithelioid cells with palely eosinophilic, granular to clear cytoplasm and round nuclei with small nucleoli, embedded in abundant densely sclerotic stroma. Five tumors contained a spindle cell component, and 6 showed focally sheetlike areas. In all cases the tumor cells were focally arranged around blood vessels. All tumors lacked the delicate nesting vascular pattern typical of other PEComas. Mitoses ranged from 0 to 3/50 high-power field (mean 1) in all cases except 1. One tumor showed abrupt transition to areas with strikingly pleomorphic morphology, marked nuclear atypia, frequent mitoses (22/10 high-power field), and fascicular and nested architecture. This was the only case with necrosis. All tumors were immunopositive for desmin (usually diffusely) and HMB-45 (generally in scattered cells); 12/13 (92%) expressed smooth muscle actin, 11/12 (92%) caldesmon, 11/12 (92%) microphthalmia transcription factor (D5), and 3/13 (23%) melan-A. Only 1 (8%) was focally S-100 positive. All tumors were negative for epithelial membrane antigen, PAN-K, and KIT (CD117). Follow-up was available for 9 patients, ranging from 10 to 64 months (median, 33). One patient (whose tumor showed transition to high-grade malignant morphology) developed metastases to lung, liver, and abdominal wall. No other tumor has recurred or metastasized thus far. Sclerosing PEComa is a distinctive variant with a predilection for the pararenal retroperitoneum of middle-aged women. Sclerosing PEComas seem to pursue an indolent clinical course, unless associated with a frankly malignant component. Long-term follow-up will be required to confirm these findings.

CD1a expression in PEComas

According to the World Health Organization classification, neoplasms with perivascular epithelioid cell differentiation (PEComas) are mesenchymal tumors composed of histologically and immunohistochemically distinctive PEC. Generally, nearly all PEComas have immunoreactivity for both melanocytic (HMB-45 and/or melan A) and smooth muscle (actin (SMA) and/or desmin) markers. Recently the authors reported that benign clear cell sugar tumor of the lung, one of the PEComas, expressed CD1a. Therefore the purpose of the present study was to investigate the relationship between PEComas and CD1a expression. Nineteen PEComas were obtained, which included angiomyolipoma of the kidney or liver, lymphangiomyomatosis of the uterus or lung and clear cell sugar tumor of the lung. Eighteen tumors had alpha-SMA and HMB-45 expression and 16 had melan A expression. In contrast, all 19 tumors had CD1a expression. The present study confirms CD1a expression in many cases of PEComa. These data suggest that CD1a expression can be an additional new marker for PEComas and also supports the distinct and integrated disease entity of PEComas.

Tumors showing perivascular epithelioid cell differentiation: a clinicopathologic study of 39 cases

To investigate the clinicopathologic features of tumors showing perivascular epithelioid cell differentiation (PEComas). The clinicopathologic data of 39 cases pf angiomyolipoma (AML), 17 males and 22 females, with the primary focus in the kidney on 30 cases, in the liver in 4 cases, in the lung, uterus and broad ligament, abdominal wall, retroperitoneum, and nasal cavity in 1 case respectively, were analyzed. Immunohistochemistry (HIC) was used to detect the expression of pan-cytokeratin (CK), S-100 protein, smooth muscle actin (SMA), desmin, vimentin, HMB45, Melan-A, microphthalmia transcription factor (MiTF), CD117, and CD34 in the specimens of the tumors obtained during operation. Twenty patients were followed up. Pathological examination showed branched capillaries or arterioles, often thick-walled similar to those in the renal cell carcinoma, and the cancerous cells consisting of the mixture of epithelial cells and spindle cells. HIC showed that the expression rates of Melan-A, HMB45, MITF, SMA, desmin, S-100 protein, vimentin, CD117, CK, and CD34 were 95% (37/39), 72% (32/39), 46% (18/39), 82% (32/39), 27% (10/39), 15% (6/39), 82% (32/39), 10% (4/39), 0, and 0 respectively. Clinical follow-up showed 1 patient alive with tumor, and 19 alive free from disease. PEComas have distinctive morphological and immunohistochemical features.

Pecoma of the lung: a benign tumor with extensive 18F-2-deoxy-D-glucose uptake

A case of lung pecoma (i.e. tumors showing perivascular epithelioid cell differentiation) with extensive 18F-2-deoxy-D-glucose (FDG) uptake in PET/CT study is reported. Pecomas of the lung--which include the better known clear cell 'sugar' tumor--are a subset of extremely rare lung tumors which usually react positively to both melanocytic and smooth muscle markers. Although widely presumed as benign in computed tomography (CT) and positron emission tomography (PET)/CT studies they depict as malignant, thus complicating the preoperative diagnosis. A subset of pecomas could conceal a malignant potential.

Benign clear (sugar) cell tumor of the lung with CD1a expression

Reported herein is a case of benign clear cell tumor of the lung in a 60-year-old man. Chest X-ray and CT examination revealed an abnormal nodule with homogenous density and a clear margin in the lower lobe of the left lung. The resected tumor was 13 mm in size, well-circumscribed and was graysh-white on cut surface. Histological examination showed a diffuse growth pattern of polygonal tumor cells with indented and pleomorphic nuclei, and clear abundant cytoplasm with a distinct cell border surrounded by thin-walled vascular spaces and sinusoid-type vessels. The clear cytoplasm contained numerous glycogen granules as demonstrated by PAS staining. In the present case there was focal immunoreactivity for S-100 protein, HMB-45, neuron-specific enolase, cathepsin B and melan A, which are consistent with reported immunohistochemical staining patterns of benign clear cell tumor. Based on these findings, the tumor was diagnosed as a benign clear cell tumor of the lung. Although most clear cell tumors are considered to belong to the family of neoplasms with perivascular epithelioid cell differentiation (PEComas), histogenesis of benign clear cell tumor of the lung has remained unclear. This first report of CD1a expression in this tumor might provide a new insight into its histogenesis and diagnosis.

Multicentric Aggressive Angiomyolipomas: A Rare Form of PEComas

4School of Medicine, China Medical University, Taichung, Taiwan. eoplasms with perivascular epithelioid cell differentiation (PEComas) are mesenchymal tumors composed of distinctive perivascular epithelioid cells [1]. PEComas can be found in various organs [2]. Angiomyolipoma (AML) is one of the PEComa family, which is benign in entity and the most common mesenchymal tumor of the kidney [1, 2]. Malignant AML is extremely rare and most of them are found to be epithelioid AML histopathologically [1, 3]. Imaging features of multifoci AMLs have rarely been reported in the literature [3–5]. We describe the case of a 60-year-old woman with a huge left renal AML who subsequently developed multiple malignant AMLs in the lungs, lymph nodes, mediastinum, and cervical and thoracic spine. The imaging and pathologic features are presented. The pathogenesis of multicentric AMLs is discussed.

PEComa: what do we know so far?

PEComas (tumours showing perivascular epithelioid cell differentiation) are a family of related mesenchymal neoplasms that include angiomyolipoma, lymphangiomyomatosis, clear cell "sugar" tumour of the lung, and a group of rare, morphologically and immunophenotypically similar lesions arising at a variety of visceral and soft tissue sites. These tumours all share a distinctive cell type, the perivascular epithelioid cell or "PEC' (which has no known normal tissue counterpart). PEComas show a marked female predominance and are composed of nests and sheets of usually epithelioid but occasionally spindled cells with clear to granular eosinophilic cytoplasm and a focal association with blood vessel walls. PEComas appear to arise most commonly at visceral (especially gastrointestinal and uterine), retroperitoneal, and abdominopelvic sites, with a subset occurring in somatic soft tissue and skin. Nearly all PEComas show immunoreactivity for both melanocytic (HMB-45 and/or melan-A) and smooth muscle (actin and/or desmin) markers. A subset of PEComas behave in a malignant fashion. This review examines the members of the PEComa family, with an emphasis on lesions arising outside of the kidney, lung and liver, and discusses preliminary evidence for pathological features that might predict malignant behaviour.

Erratum to: Perivascular epithelioid cell tumor (PEComa) of the uterine cervix associated with intraabdominal "PEComatosis": A clinicopathological study with comparative genomic hybridization analysis

Background The World Health Organization recently recognized a family of neoplasms showing at least partial morphological or immunohistochemical evidence of a putative perivascular epithelioid cell (PEC) differentiation. These tumors include angiomyolipoma (AML), clear cell "sugar" tumors of the lung (CCST), lymphangioleiomyomatosis (LAM), clear cell myomelanocytic tumors of the falciform ligament and distinctive clear cell tumors at various other anatomic sites.

Malignant Perivascular Epithelioid Cell Tumour ("PEComa") of Soft Tissue

Tumours of perivascular epithelioid cells (PEComas) are being increasingly reported at visceral and somatic sites. Both benign and malignant variants have been identified, although clinical follow-up is often limited, which prevents meaningful predictions of behavior. We report the case of a malignant soft tissue PEComa with histologically confirmed regional lymph node metastases and radiologically confirmed pulmonary metastases. The light microscopic appearance and immunohistochemical profile (HMB-45, smooth muscle actin positive) and electron microscopic appearance support perivascular epithelioid cell differentiation.

Perivascular epithelioid cell tumor (PEComa) of the uterine cervix associated with intraabdominal "PEComatosis": A clinicopathological study with comparative genomic hybridization analysis

BackgroundThe World Health Organization recently recognized a family of neoplasms showing at least partial morphological or immunohistochemical evidence of a putative perivascular epithelioid cell (PEC) differentiation. These tumors include angiomyolipoma (AML), clear cell "sugar" tumors of the lung (CCST), lymphangioleiomyomatosis (LAM), clear cell myomelanocytic tumors of the falciform ligament and distinctive clear cell tumors at various other anatomic sites.Case presentation & methodsA 41-year old gravida-1 para-1 with tuberous sclerosis presented with an incidentally identified 2.2 cm mass. The morphology and immunohistochemical profile was consistent with PEComa. Distinct aggregates of HMB-45 epithelioid cells were present in an occasionally distinctive perivascular distribution in the myometrium, small bowel lamina propria and ovarian hila. These distinctive aggregates, for which we propose the designation "PEComatosis" based on their intraabdominal distribution, did not display cytological atypia, mitotic activity or necrosis. CGH and DNA ploidy analysis showed a balanced chromosomal profile and diploid nuclei, respectively. There was no recurrence or metastases at 35 months' follow-up. Fifty-one previously reported cases of non-AML, LAM and CCST PEComas [perivascular epithelioid cell tumors- not otherwise specified (PEComa-NOS)] are reviewed.ConclusionsThe lesions may be a reflection of tumor multicentricity, in which each may be a potential nidus for the development of future more well-developed tumors. Alternatively, they may be a manifestation of a poorly understood "field effect", in which there is an increased propensity to develop tumors of this type throughout the abdomen. Finally, and least likely in our opinion, they may represent tumor spread from its primary site.