Renal epithelioid angiomyolipoma: Histopathologic review,immunohistochemical evaluation and prognostic significance

Epithelioid angiomyolipoma (EAML) is considered to be a potentially malignant tumor and requires a differential diagnosis from renal cell carcinoma. In this study, we assessed the clinicopathologic features of renal EAML and evaluated the prognostic significance. Among 78 angiomyolipoma (AML) patients, a total of 5 EAMLs were identified, accounting for 6.4% of the total AML cases. The mean age was 41.4 years, and the average tumor size was 12.7 cm in diameter. Association of tuberous sclerosis complex was identified in two cases. One EAML case showed malignant behavior with local recurrence and distant metastasis. The malignant EAML had a larger tumor size, a higher percentage of epithelioid component and atypical epithelioid cells, ≥2 mitoses per 10 high power fields with atypical mitosis, necrosis, extrarenal extension, and carcinoma‐like growth pattern. Furthermore, the malignant case revealed p53 immunoreactivity and decreased membranous E‐cadherin expression. Pathologic evaluation of adverse prognostic factors will be helpful for risk stratification and prognosis estimation of EAML patients.     

Malignant angiomyolipoma in the liver: a case report with pathological and molecular analysis

Malignant angiomyolipoma (AML) of the liver is rare. We report a case of AML with malignant transformation and metastases. A 30-year-old man had developed giant hepatic masses. Microscopically, the periphery of the tumor showed components of classic hepatic AML, but the central region contained atypical epithelioid components with extremely pleomorphic and hyperchromatic nuclei with frequent mitotic figures. Immunohistochemical analysis revealed that the epithelioid cells were positive for HMB-45 and smooth muscle actin. Furthermore, the atypical epithelioid cells displayed P53 immunoreactivity and mutation at exon 7 for p53. The tumor showed a typical monoclonal pattern but no loss of heterozygosity or microsatellite instability. Markedly atypical epithelioid cells with vascular invasion, distant metastasis, and fatal outcome were interpreted as malignant characteristics of hepatic AML. It is suggested that large tumor size, pleomorphic nuclei with high proliferation activity, and P53 immunoreactivity may predict the existence of malignant transformation of hepatic AML.     

Retroperitoneal epithelioid angiomyolipoma leading to fatal outcome

Epithelioid angiomyolipoma (AML) is a newly established variant of AML, characterized by monomorphous epithelioid cells that show HMB-45 immunopositivity, and it often displays aggressive behavior. To date, they have mostly appeared in the kidneys; however, the present autopsy case of a 43-year-old female without the stigmata of tuberous sclerosis complex had a huge retroperitoneal mass, accompanied by involvement of the regional lymph nodes. Histopathologically, the tumor was composed of round, polygonal or short spindle-shaped monomorphous cells with abundant eosinophilic cytoplasm and large nuclei with frequent multinucleation. Mitotic figures were scattered. Mature fat cells and thick-walled abnormal blood vessels were totally absent. Immunohistochemically, the tumor cells were reactive with HMB-45 and alpha-smooth muscle actin antibodies. In spite of curative surgery and repeated radio- and chemotherapy, the tumor continued to grow and brought about the patient's death 4 years after the initial symptoms. At autopsy, the peritoneal cavity was filled with the tumor mass exceeding 5.5 kg. Histopathological features were essentially the same as those of biopsy samples, but the cellular pleomorphism and emperipolesis were more easily identified. This report calls attention to this unusual manifestation of AML in the retroperitoneum and the importance of distinguishing it from sarcomas and/or paragangliomas.     

Hepatic epithelioid angiomyolipoma with an unusual pathologic appearance: expanding the morphologic spectrum

Hepatic epithelioid angiomyolipoma (AML) is a rare lesion that is characteristically composed of a predominant or exclusive population of epithelioid cells coexpressing melanocytic and myogenic markers. The cystic variant of epithelioid AML is exceedingly uncommon. In this study, we present the clinicopathological features of a case of hepatic epithelioid AML with remarkable cystic degeneration in a 34-year-old female as well as with a literature review. A magnetic resonance imaging scan revealed a well-defined 30 cm × 25 cm hepatic mass. Sectioning of the well-defined mass revealed a non-encapsulated tumor that was multiloculated with amorphous necrotic tissue and hemorrhagic fluid. The inner cystic wall was rough and brownish-black in color. Microscopically, the tumor largely consisted of epithelioid cells that comprised approximately 95% of the total neoplastic components but also contained some spindle myoid cells, mature fat, and a thick-walled vasculature. Both intracellular and extracellular hyaline globules were frequently identified. Necrosis and invasive growth patterns were also present. By immunohistochemistry, spindle-epithelioid neoplastic cells were variably positive for Melan-A, HMB45, and SMA but were uniformly negative for epithelial and hepatocytic markers. This is the third report of a cystic AML in liver. The patient was followed for 71 months without any evidence of metastasis or recurrence.     

Angiomyolipoma mimicking true lipoma of the liver: report of two cases

Hepatic angiomyolipoma (AML) is very rare and only about 80 cases have been reported. The tumor is fundamentally heterogeneously composed of the three tissue components of blood vessels, smooth muscle cells (SMC), and fat cells. Two cases of hepatic AML are reported here, both of which are histologically composed predominantly of a fat cell element and resembled true lipoma (lipomatous AML). However, careful examination of both tumors revealed the presence of a small amount of epithelioid SMC, especially around blood vessels. Immunohistochemical study using monoclonal antibody for melanoma (HMB-45) clearly revealed a small amount of HMB-45-positive SMC around the blood vessels and scattered in the diffuse fat cell growth in both tumors. Since no liver tissue components or primary liver tumors are reactive with HMB-45 except AML cells, the presence of HMB-45-positive cells within the tumor clearly established the diagnosis of hepatic AML. Any fatty tumor or focal fatty lesion of the liver that superficially resemble true lipomas should be tested for the presence of HMB-45-positive SMC in the tumor to differentiate it from AML.     

Gastrointestinal stromal tumor (GIST) in southern Taiwan: a clinicopathologic study of 93 resected cases

The purpose of this study was to determine the clinicopathologic features of gastrointestinal stromal tumor (GIST) in southern Taiwan. The pathology files from a medical center in southern Taiwan (1993 to 2003) were searched for primary mesenchymal tumors of the gastrointestinal tract. Hematoxylin/eosin sections and history were reviewed, and immunohistochemistry was performed using anti-CD 117, CD34, smooth muscle actin (SMA), and S-100 protein. Only primary resected GISTs were included in this study. Univariate and multivariate analyses were carried out using the T-test to evaluate the significance of primary tumor size and mitotic activity for the prediction of recurrence and metastasis. A total of 121 surgically resected primary mesenchymal tumors were identified, and 93 of these were GISTs. These 93 patients showed a slight female predominance (male: female = 1:1.2). The clinical presentations were variable and site-dependent. The most common tumor locations were the stomach (57%) and the small intestine (39%). Microscopically, 88 tumors (95%) were composed of spindle cells, the remaining five (5%) consisted of mixed epithelioid and spindle cells. No pure epithelioid type GIST was found. In addition to CD117, 66 cases (71%) were positive for CD34, 23 cases (25%) were positive for SMA, and 19 cases (21%) were positive for S-100. In a mean follow-up time of 27.3 months (median: 26 months), 19 cases (20.6%) were clinically malignant and mainly manifested as liver metastases (seven cases, 37% of malignant GISTs). Univariate analysis revealed that both primary tumor size and mitotic activity were significantly increased in the group affected by recurrence and/or metastasis (p = 0.001 and 0.035, respectively). Compared to GISTs in the western countries, those in southern Taiwan are characterized by a slight female predominance, a relatively higher frequency of small intestinal localization, a higher rate of S-100 protein expression, and a less aggressive behavior. Tumor size and mitotic activity were useful predictors of malignancy.     

上皮样血管平滑肌脂肪瘤的临床病理特征

目的:探讨上皮样血管平滑肌脂肪瘤(epithelioid angiomyolipoma,EAML)的临床病理学特征.方法:回顾性分析17例病理诊断为EAML的组织学形态、免疫组织化学特点、临床及随访资料.结果:男5例,女12例,年龄21~62(平均31.2)岁,其中14例发生于肾脏(3例伴有子宫平滑肌瘤,2例伴有宫内孕);2例发生于肝脏,1例发生于腹腔;肿瘤最大径3~15 cm,镜下瘤细胞呈上皮样巢、片状分布,可见围绕血管呈放射状排列的结构;细胞体积大,卵圆形、梭形,胞质丰富,异型明显,核分裂少见,其中2例伴有出血、坏死.免疫组织化学HMB-45,Melan-A,SMA阳性,vimentin,ER和PR表达率分别为41%(7/17),23%(4/17)以及35%(6/17).17例EAML均行肿瘤根治或肿瘤切除术,术后随访5~52个月,1例2年后肝肺转移死亡,其余16例均健在,无复发及转移.结论:EAML多发生于女性,可能与激素水平有关;肾脏最常见,其次为肝、腹腔;病理形态多样,免疫组织化学对其诊断有重要价值,手术效果好,有转移可能.     

Hepatic angiomyolipoma: a series of six cases with emphasis on pathological-radiological correlations and unusual variants diagnosed by core needle biopsy

Hepatic angiomyolipoma is rare and may pose differential diagnostic difficulty, particularly if encountered in core needle biopsy. We studied 6 cases from 5 males and one female (median age, 48.6 yrs). All presented with non-specific symptoms or an incidentally discovered tumor mass. Two patients had a remote history of chemotherapy for hematological neoplasms (acute lymphoblastic leukemia and Hodgkin lymphoma respectively) and another had clear cell renal cell carcinoma and anaplastic pancreatic carcinoma diagnosed at autopsy without definable syndrome. None of the patients had evidence of the tuberous sclerosis complex or renal or other extra-renal angiomyolipoma. Three tumors were resected completely and three have been only biopsied and followed up. None of the resected cases recurred at a mean follow-up of 35 months. Histologically, tumors were classified as classical triphasic (1), lipomatous (2), epithelioid/oncocytoid (1), epithelioid trabecular (1) and myelolipoma-like (1). The adjacent liver parenchyma was normal in 3 cases, showed pigment cirrhosis in one case and mild fatty change in another case. One case had clinically diagnosed but histologically unverified cirrhosis. The initial diagnostic impression/frozen section was misleading in 5 of the cases and included vascular lesion, focal fatty change, myelolipoma, hepatocellular tumor and oncocytic neoplasm. All tumors expressed HMB45 and variably desmin. One epithelioid lesion expressed HMB45 and TFE3, but lacked desmin expression. In conclusion, hepatic angiomyolipomas are increasingly recognized as incidental findings during surveillance for cirrhosis or investigations for unrelated conditions. Awareness of their diverse morphological spectrum in liver biopsy is necessary to avoid misdiagnosis as hepatocellular carcinoma, metastatic melanoma or other malignant neoplasms.     

Angiomyolipoma of the kidney: expanding disease spectrum demonstrated by 3 cases.

We report 3 recent cases of angiomyolipoma of the kidney. Although generally regarded as a benign neoplasm, angiomyolipoma rarely behaves in an aggressive manner, producing complicated clinical courses leading to metastasis and death. The presence of epithelioid elements within the tumor can result in difficulty differentiating benign from malignant angiomyolipoma and differentiating this tumor from renal adenocarcinoma. The presence of lymph node involvement can cause difficulty in differentiating multicentric disease in lymph nodes from metastasis to lymph nodes. The presence of cytologic abnormalities in the primary tumor can result in difficulty in differentiating atypia in benign angiomyolipoma from malignant sarcomatous transformation of a benign lesion. The 3 cases reported show many of these problems. Criteria for predicting malignancy in epithelioid tumors and sarcomatous transformation are not well recognized because of the rarity of this entity. The typical immunophenotype of all types of angiomyolipoma (cytokeratin-negative and melanomarkers-positive) is very useful in diagnosis but does not help in the differentiation from renal adenocarcinoma at frozen section. We report the empiric use of Ki67 and p53 in these cases as adjuncts to clinical and histologic assessment in predicting behavior. High Ki67 expression was a feature of malignant epithelioid angiomyolipoma. Low levels of p53 expression were seen in the angiomyolipoma with sarcomatous transformation. Benign angiomyolipomas were consistently negative for both Ki67 and p53.     

Epithelioid angiomyolipoma of the kidney: case report

Renal angiomyolipoma is a benign tumour histologically characterized by a mixture of adipose tissue, smooth muscle cells and thick walled blood vessels. Long-believed to be a benign hamartoma, angiomyolipoma is now considered to arise from perivascular epithelioid cells. Epithelioid angiomyolipoma is a rare type of angiomyolipoma, composed partially or completely of epithelioid cells, with a potentially aggressive behaviour. Histologically it can mimic renal cell carcinoma. Positivity for HMB45, Melan A, CD68 and CD117 are useful for diagnosis. Herein, we report the clinicopathologic and immunohistochemical features of a renal tumour composed of large epithelioid mononucleated or multinucleated cells with abundant acidophilic cytoplasm and prominent nucleoli. Despite the morphologic resemblance of this tumour to renal cell carcinoma, its phenotype (HMB45, Melan A and CD68 positivity and keratin negativity) parallels the phenotypic profile of angiomyolipoma. Therefore, immunohistochemistry should be considered when diagnosing this variant of angiomyolipoma.     

Monotypic epithelioid angiomyolipoma of the adrenal gland: an unusual site for a rare extrarenal tumor

Epithelioid angiomyolipoma (AML) is an uncommon renal mesenchymal tumor with malignant potential and is frequently associated with tuberous sclerosis. Extrarenal AMLs are rare, and to the best of our knowledge, this is the first reported case of a primary monotypic epithelioid AML of adrenal gland in a patient without evidence of tuberous sclerosis. The patient is a 42-year old man who presented with retroperitoneal hemorrhage resulting from spontaneous rupture of adrenal mass. Histologically, the tumor showed a prominent component of epithelioid smooth muscle cells with slightly pleomorphic nuclei, sometimes with prominent nucleoli and eosinophilic cytoplasm resembling oncocytic tumors. Epithelioid cells were positive for melanoma (HMB45 and positive MelanA) and smooth muscle markers (α-smooth muscle–specific actin), but not for epithelial markers (cytokeratin, EMA). Differential diagnosis from renal cell carcinoma, adrenal gland carcinoma, and metastatic carcinoma is often challenging because of its epithelioid morphology. Because primary and secondary malignant tumors are much more common and aggressive neoplasms, establishing the correct diagnosis has important therapeutic and prognostic implications.     

Malignant epithelioid angiomyolipoma of the kidney in a patient with tuberous sclerosis: an autopsy case report with p53 gene mutation analysis

We report an autopsy case of malignant epithelioid angiomyolipoma in a 36-year-old male tuberous sclerosis patient. He had been diagnosed to have a bilateral renal tumor 20 years previously. The left kidney had been surgically resected at the age of 34, and the left renal tumor was pathologically diagnosed as classic angiomyolipoma and epithelioid angiomyolipoma. He suddenly died of cardiac arrest, and at autopsy the right kidney weighed 7120 g. The tumor presented with massive necrosis invading the inferior vena cava, but was not hemorrhagic. Microscopic examination revealed tumor cells varying in size with a predominantly solid proliferation pattern and marked atypical large cells with vesicular nuclei and abundant eosinophilic cytoplasm. Mitotic figures were often encountered, and atypical forms were also present. Metastatic lesions were identified in the right lung, liver, diaphragm, and mesentery. Immunohistochemical examination showed epithelioid angiomyolipoma cells that were focally reactive for HMB-45 and showed diffuse positive staining for Melan-A. No mutation was detected in the p53 gene by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis despite diffuse immunoreactivity for p53. This case was proven to be malignant because of the occurrence of distant metastases, and showed that p53 mutations are not always associated with malignant transformation in epithelioid angiomyolipoma.     

肝脏血管平滑肌脂肪瘤9例临床病理分析

目的探讨肝脏血管平滑肌脂肪瘤(hepatic angiomyolipoma,HAML)的临床病理特点、诊断及鉴别诊断。方法对9例HAML进行临床病理学观察与免疫组化标记及复习有关文献。结果 9例HAML年龄28～56岁,平均44.2岁,均无结节硬化症。术前影像诊断多数为肝癌。眼观:肿瘤直径1.2～14 cm。肝左叶4例、肝尾状叶3例和肝右叶2例。肿瘤境界清楚,无包膜,质地脆、易碎,可见出血、坏死。镜检:瘤组织由上皮样细胞、平滑肌样细胞、脂肪组织和厚壁血管组成。上皮样细胞体积大或巨大,呈多边形,胞质丰富,嗜酸性或空泡状,核仁明显,可见核内包涵体,偶见多核巨细胞。平滑肌样细胞呈梭形,9例中有4例几乎缺如脂肪组织。瘤细胞弥漫性或巢团状排列。瘤组织出血、坏死明显,呈浸润性边缘。免疫组化标记:瘤细胞HMB-45及Melan-A阳性,SMA和vimentin散在阳性,CK、EMA、AFP均阴性。结论 HAML是一种罕见的间叶组织源性肿瘤,多见于女性,组织学上以单一方向分化的大上皮样细胞为主,瘤细胞较为特异的表达HMB-45及Melan-A。免疫组化标记可与其它肝脏肿瘤鉴别。     

Estrogen receptor is significantly associated with the epithelioid variants of renal angiomyolipoma: a clinicopathological and immunohistochemical study of 67 cases

Perivascular epithelioid cells (PEC) in angiomyolipoma (AML) were recently proposed to be its most common progenitor cells. Histologically, triphasic components were present in various proportions, but were overwhelmingly myogenic in epithelioid variants of AML. Despite histological discrimination, the immunophenotypic profiles between triphasic and epithelioid AML have never been compared. The aim of the present study was to clarify the identity of PEC by using immunoreactivity to estrogen receptor (ER), progesterone receptor (PR), bcl-2 and placenta alkaline phosphatase (PLAP), and to use this information to compare triphasic and epithelioid AML. A total of 33 out of 67 cases of renal angiomyolipoma that underwent surgery were reviewed over the period 1998-2003. Two cases were associated with tuberous sclerosis. Ten patients had other malignant tumors, and three patients had a nodal extension. Immunohistochemistry showed that bcl-2 (59.4%), PLAP (46.9%), HMB-45 (100%) was predominantly localized around vessels. The stem cell markers were absolutely negative in all AML types. The estrogen receptors were positive in 14 cases (42.4%) and the progesterone receptors were positive in five cases. Bcl-2 and both female sex hormone receptors were significantly more frequent in the epithelioid variant of AML than in the triphasic type. Perivascular epithelioid cells express bcl-2, ER, PR and PLAP, and ER could be partly associated with myogenic proliferation.     

Renal epithelioid angiomyolipoma with epithelial cysts: demonstration of Melan A and HMB45 positivity in the cystic epithelial lining

Renal angiomyolipoma (AML) may present as rare variants such as epithelioid and AML with epithelial cysts posing difficulties for the diagnosis to the surgical pathologist. We report a case of a 46-year-old male patient presenting a 5-cm solid tumor in the lower pole of the left kidney, with cystic changes at cut surface. The tumor exhibited 95% of epithelioid cells with atypical nuclei. A small focus of typical AML was observed. The immunoprofile of tumor cells was classical of AML including expression of melanocytic markers such as HMB45 and Melan A. We report the immunohistochemical study of the cystic component in an epithelioid AML. In contrast to the immunoreactivity reported in typical AML, the present case shows obvious expression of melanocytic markers in the cystic epithelial lining. This is strong evidence that these cysts are neoplastic and derived from AML, rather than entrapped native collecting duct epithelium.     

Multifocal angiomyolipoma affecting the liver and lung without tuberous sclerosis

The occurrence of angiomyolipoma (AML) in tissue other than the kidney is uncommon, as is multiple AML developing exclusively in organs other than the kidney. This report describes a case in which AML occurred multifocally in the liver and lung, but spared the kidney, and which might have been associated with tuberous sclerosis complex (TSC). A Japanese woman underwent a partial hepatectomy for a suspected malignant liver tumour at the age of 57. The tumour consisted predominantly of a trabecular arrangement of myoid cells with a sinusoidal pattern and inflammatory cell infiltration, and was diagnosed as a primary liver AML by HMB-45 immunoreactivity. Five years later, multiple nodules were found in both lungs, for which video assisted thoracic surgery was performed. The tumour showed a mixture of epithelioid cells containing HMB-45 positive material and mature lipocytes, and was subsequently diagnosed as AML. Molecular analysis of both lesions showed no allelic loss of the TSC1 and TSC2 regions. Molecular analysis of the tumours ruled out an association with TSC, and both liver and lung lesions displayed benign histological features, so that these were probably multifocal lesions of AML without TSC.     

Hepatic angiomyolipoma resembling an inflammatory pseudotumor of the liver. A case report

Hepatic angiomyolipoma (AML) may demonstrate a marked histologic diversity and is frequently misdiagnosed. HMB45 is a promising marker for this tumor and is expected to facilitate the recognition of some AMLs with unusual morphology. We report on a case of hepatic AML exhibiting histologic features that were similar to inflammatory pseudotumor (IPT) or to IPT-like follicular dendritic cell (FDC) tumor of the liver. The patient was a 21-year-old Japanese woman with a mass in the left lobe of the liver (70 x 73 mm). There were no clinical features of tuberous sclerosis. Histologically, numerous inflammatory cells, including small lymphocytes, plasma cells, and histiocytes, showed diffuse infiltration throughout the lesion. However, the present case also shared some of the morphologic findings of hepatic AML, including clusters of smooth muscle cells with clear cytoplasm, a few scattered adipose cells, and thick-walled blood vessels. Moreover, the smooth muscle cells consisted of spindle-shaped cells or larger, more rounded cells with either clear cytoplasm or eosinophilic epithelioid cell features positive for vimentin, muscle-specific actin, and smooth muscle actin. HMB45 immunostaining confirmed the diagnosis of AML. The present case indicates that IPT or IPT-like FDC tumor should be added to the list of differential diagnoses for AML of the liver.     

Mucocutaneous angiomyolipoma. A report of 2 cases arising in the nasal cavity.

OBJECTIVE: Angiomyolipoma (AML) is a distinctive tumor that usually occurs in the kidney and rarely in the liver. Angiomyolipoma of other sites is extremely rare, and, to our knowledge, only 2 cases have been described in the nasal cavity. We present 2 additional cases of AML of the nasal cavity and discuss the difference between them and renal AML. CASE REPORTS AND PATHOLOGIC FINDINGS: Two tumors in a 66-year-old man and an 88-year-old woman without tuberous sclerosis are described. They showed 20-mm, well-circumscribed, polypoid shapes. Histologically, they were composed of mature smooth muscle cells, fat cells, and various-sized blood vessels. In addition, aggregated small lymphocytes were noted. Neither epithelioid smooth muscle cells nor HMB45 immunoreactivity was seen in either case. CONCLUSIONS: The clinicopathologic features of AML of the nasal cavity are distinct from renal and hepatic AML and are common to those of AML arising in the skin and oral and pharyngeal mucosa. The term mucocutaneous angiomyolipoma is thought to be appropriate to express these characteristic tumors.     

Renal epithelioid angiomyolipoma: a case report and literature review

BACKGROUND: Renal epithelioid angiomyolipoma is a recently recognized variant of angiomyolipoma, closely simulating renal cell carcinoma both clinically and histologically. Only a relatively small number of cases of epithelioid angiomyolipoma of the kidney have been reported. AIM: To highlight clinicopathological features of this rare tumour. OBSERVATION: We report herein a new case of renal epithelioid angiomyolipoma in a 38-year-old male with no stigmata of tuberous sclerosis. The tumour was composed of diffuse sheets of epithelioid cells, small numbers of adipocytes and occasional blood vessels. Immunohistochemically, neoplastic cells were immunoreactive for HMB-45, but negative for cytokeratin. The patient showed no evidence of recurrence or metastatic disease one year after radical nephrectomy. CONCLUSIONS: Epithelioid angiomyolipoma may be locally aggressive and can metastasise; therefore, long-term post-operative follow-up is mandatory.     

15例具有血管周上皮样细胞分化的肿瘤临床病理分析

目的探讨具有血管周上皮样细胞分化的肿瘤(perivascular epithelioid cell tumor,PEComa)临床病理特征及免疫表型。方法对15例PEComa行EnVision两步法免疫组化及特殊染色,并分析其临床表现、病理学特征和免疫组化特点。结果 15例PEComa中13例为女性,且术后无复发。肿瘤可发生在身体任何部位,以肝脏和肾脏最多见,有包膜,多为实性,可有出血。特征性组织学改变是肿瘤细胞围绕血管生长。PAS染色显示该肿瘤细胞中有糖原物质沉积,弹力纤维染色显示该肿瘤中的血管壁缺乏弹力层。免疫组化显示所有PEComa病例均明显表达HMB-45、Melan-A、SMA,Ki-67阳性率不高。结论 PEComa是一组具有恶性潜能的肿瘤,多发于女性,来源于血管周上皮样细胞。大部分肿瘤呈良性过程,生物学分级极低,预后良好;极少部分病例可发生转移,预后不佳。免疫组化检测对其组织来源、生物学行为具有提示意义,并可辅助诊断。