Monotypic epithelioid angiomyolipoma of the liver

AIMS: Monotypic epithelioid angiomyolipoma is a recently recognized renal tumour, which is composed purely of epithelioid cells coexpressing markers of both smooth muscle differentiation and melanogenesis (HMB45). We report here the first case of monotypic epithelioid angiomyolipoma arising in the liver. CASE DETAILS: A 30-year-old woman without tuberous sclerosis complex (TSC) was incidentally found to have a hepatic mass by ultrasonography. Grossly, the resected tumour showed a nodule-in-nodule appearance, with large areas of haemorrhagic necrosis. Microscopically, the tumour was composed of pleomorphic epithelioid cells with clear, eosinophilic cytoplasm. Neither adipocytes nor abnormal vessels were recognized in the tumour. Immunohistochemically, the tumour cells were strongly positive for HMB45 and S100 protein, focally positive for desmin, vimentin and smooth muscle actin, and negative for epithelial markers (cytokeratins, EMA). Ultrastructural analysis showed numerous dense granules with some striated ones resembling melanosomes, myofilaments and pinocytic vesicles in the cytoplasm. Molecular analysis showed no allelic loss of the TSC2 region or 12 other chromosomal regions. The patient is free of disease over 1 year after the operation. CONCLUSION: We consider that this hepatic tumour is closely related to angiomyolipoma, and a counterpart of renal monotypic epithelioid angiomyolipoma.     

Clinicopathologic features of renal epithelioid angiomyolipoma: report of one case and review of literatures

Epithelioid angiomyolipoma (EAML) is a rare renal mesenchymal tumor with malignant potential and is frequently associated with tuberous sclerosis complex (TSC). As metastasis of the tumor cells occur early, EAML is considered a potentially malignant tumor type and intrigues further research on it. Under the microscope, we could find the tumor was composed of atypical polygonal cells sheet mixed with classic angiomyolipoma (AML) components such as blood vessels with notable thick vascular walls, smooth muscle-like cells and adipocytes. Immunohistochemical studies showed that epithelioid cells were focally positive for vimentin, melanocytic markers (HMB-45), myoid markers (α-smooth muscle actin), CD34 and CD68; negative for cytokeratin, epithelial membrane antigen, CD10, and S-100. And the Ki67 index showed approximately 3%. Here, we report the morphological and immunohistochemical features of clinically or histologically malignant renal EAML and discuss its diagnosis, differential diagnosis and the prognosis.     

Primary perivascular epithelioid cell tumor of the bladder

The perivascular epithelioid cell family of tumors includes angiomyolipoma, clear cell “sugar” tumor of the lung, lymphangioleiomyomatosis, and clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres. Less frequently, perivascular epithelioid cell tumors arise in various other locations throughout the body including soft tissue, bone, and visceral organs. We report a case of a 23-year-old man who presented with 2-month history of frequent micturition and odynuria. Based on clinical examination, ultrasound computed tomography imaging, surgical operation, and histopathologic studies, a definitive diagnosis was made. Further characteristic images and pathology of this disease are discussed.     

Epithelioid angiomyolipoma of the liver: case report and review of the literature

Hepatic angiomyolipoma is a rare tumor. Here we describe a case and review the literature.     

C-Kit-positive metastatic malignant pigmented clear-cell epithelioid tumor arising from the kidney in a child without tuberous sclerosis

We report the first pediatric case of malignant pigmented epithelioid clear-cell tumor arising from kidney; the lesion occurred in a 12-year-old girl without tuberous sclerosis. The tumor was widely metastatic to the retroperitoneum and chest, and the patient died of the disease 9 months after diagnosis, despite active chemotherapy. Pigmented epithelioid clear-cell tumor of the kidney is a rare variant of epithelioid angiomyolipoma and a member of the family of perivascular epithelioid cell tumors (PEComas). The tumor demonstrated overlapping features between clear-cell sugar tumor and epithelioid variant of angiomyolipoma. Tumor cells were positive for HMB-45 expression, negative for any evidence of muscular differentiation, and contained melanin pigment and premelanosomes in the cytoplasm. Diffuse C-Kit (CD117) positivity was identified throughout the tumor. This is the first report of C-Kit–positive malignant PEComas.     

Intravascular epithelioid hemangioendothelioma of the inferior vena cava: case report of an unusual and unpredictable vascular tumor

Vascular neoplasms are uncommon and pose a diagnostic and treatment challenge to the pathologist and surgeon, respectively. Epithelioid hemangioendothelioma is a rare neoplasm of vascular origin with an unknown etiology. Its biologic behavior lies somewhere between that of a benign hemangioma and that of a malignant angiosarcoma; however, it is unpredictable at best. Intravascular epithelioid hemangioendotheliomas have been described more often in veins than arteries, and there are only about 30 reports in the English literature. We report here the case of an epithelioid hemangioendothelioma of the inferior vena cava, which presented with abdominal pain, ascites and pedal edema.     

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.     

Uterine angiomyolipoma: case report and review of the literature

Extrarenal angiomyolipomas (AML) have been reported at various anatomical sites, but infrequently in the gynecological region. In the uterus, only a few cases have been described. We describe a uterine angiomyolipoma occurring in a 40-year-old woman without evidence of tuberous sclerosis. The tumor arose on the right wall of the uterine body and was partially cystic, and it was associated with marked degeneration. It was composed of mature adipose tissue, anomalous blood vessels and non-vascular smooth muscle cells. Immunohistochemistry revealed that non- vascular smooth muscle cells were positive for alpha-smooth muscle actin (alpha-SMA), desmin, vimentin, antihuman muscle actin (HHF35) and progesterone receptor (PR), and negative for cytokeratin, antihuman melanoma (HMB45), CD34, S-100 and estrogen receptor (ER). It is of particular interest that non-vascular smooth muscle cells were negative for HMB45, in contrast to renal and other extrarenal AML in which HMB45 immunoreactivity has been demonstrated in these cells.     

Cysts in angiomyolipoma with epithelial cysts may be consisted of entrapped and dilated renal tubules: report of a case with additional immunohistochemical evidence to the pre-existing literature

Angiomyolipoma with epithelial cysts (AMLEC) is a distinctive variant of angiomyolipoma characterized by grossly apparent epithelial cysts and a cellular, müllerian-like subepithelial stroma. Some authors suspect that the epithelial cysts mainly represent dilated entrapped native renal collecting duct epithelium, while other authors think that they represented true epithelial differentiation of the AML. Recently, it has been reported that obvious immunolabeling of melanocytic markers such as Melan A and HMB45, which are often immunolabeled in classical angiomyolipoma, are present in epithelial cysts in cases of AMLEC. Here, we report the case of a 43-year-old Japanese woman with AMLEC, and attempt to elucidate the significance of melanocytic marker immunolabeling in the cyst’s epithelium. In the present case, Melan A was labeled in the cyst’s epithelium, and was thought to reflect its labeling in renal tubules existing in the renal parenchyma outside the tumor. This finding may indicate that the cyst epithelium is derived from entrapped renal tubules inside the AML. Non-immunolabeling of the estrogen and progesterone receptors in the cyst epithelium may also suggest that the cyst epithelium is not neoplastic, in contrast to their labeling in neoplastic cells existing in cyst wall. Further examination, such as molecular analysis, is needed to determine whether these epithelial cysts is neoplastic or non-neoplastic.     

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 with epithelial cysts of the kidney in a man

Angiomyolipoma (AML) is a well-characterized tumor composed of vascular, smooth muscle and adipose elements. Recently, AML with epithelial cysts (AMLEC) has been described as a cystic variant of AML. Herein is reported an AMLEC in a 55-year-old man, and to the authors' knowledge this is the first case report of AMLEC in Japan. He was referred to hospital because of microhematuria. A left renal tumor was noted and partial nephrectomy was performed. Histology indicated that the tumor was composed of epithelial cysts, compact subepithelial stroma and muscle-predominant AML. Immunohistochemically, the subepithelial compact stroma and muscle-predominant AML were positive for HMB-45, estrogen receptor (ER), progesterone receptor (PR), CD10, smooth-muscle actin and desmin. Epithelial cysts were positive for pancytokeratin but negative for HMB-45, ER and PR. This tumor was diagnosed as AMLEC, mainly based on the immunohistochemical result that subepithelial compact stroma and muscle-predominant AML were positive for HMB-45. The patient was alive with no evidence of recurrence at 2 years postoperatively. This case was very interesting because it suggests that AMLEC should enter into the differential diagnosis of adult renal neoplasms.     

Angiomyolipoma of the liver: a reappraisal of morphological features and delineation of new characteristic histological features from the clinicopathological findings of 55 tumours in 47 patients

Nonomura A, Enomoto Y, Takeda M, Takano M, Morita K & Kasai T
(2012) Histopathology  61, 863–880 Angiomyolipoma of the liver: a reappraisal of morphological features and delineation of new characteristic histological features from the clinicopathological findings of 55 tumours in 47 patients Aims: The aim of this study was to characterize and delineate the broad histological spectrum of hepatic angiomyolipoma (AML) and to obtain a better understanding of its clinicopathological diagnosis by reviewing a large series of AMLs. Methods and results: According to the proportions of three histological components, AML could be classified into 10 types; 36 of 55 tumours (65%) were classified as myomatous, eight as myoangiomatous, six as mixed (conventional), two as lipomatous, two as myolipomatous, and one as lipomyomatous. The morphology of smooth muscle cells (SMCs) in AML was quite variable, giving a wide variety of growth patterns. Fourteen (25%) of 55 tumours showed severe cellular atypia, and invasive growth of tumour cells was found in 69% of the tumours. However, except for two autopsy cases, all of the patients were in good health at follow‐up, without metastases. Immunostaining for HMB‐45 was positive in all cases. We found frequent lymphocyte infiltration, and the occasional presence of abnormally large blood vessels around the tumour at the tumour–background liver interface, features which have not been reported previously. Conclusions: The majority of hepatic AMLs were myomatous in type, showing variable cellular morphology and growth patterns. Cellular atypia and invasive growth were frequent, indicating that hepatic AMLs often show malignancy‐like histological features. Although the majority of cases behave as benign tumours, AML should be considered to have uncertain malignant potential, and careful follow‐up of patients is recommended. Immunostaining for HMB‐45 is specific for AML, and establishes the diagnosis. The occasional presence of abnormally large blood vessels around the tumour may give new insights into the evaluation of findings from imaging.     

Perivascular epithelioid cell tumor of the uterus: immunohistochemical, ultrastructural and molecular study

A case of perivascular epithelioid cell tumor of the uterus is reported, occurring in a 32-year-old woman. The tumor (8.0 cm in dimension) showed exophytic growth from the outer half of the myometrium. Histopathologically, the tumor was composed of thick blood vessels and perivascular epithelioid cells. The neoplastic cells were strongly immunoreactive for HMB45 antigen, CD117 (c-kit), vimentin and the progesterone receptor, but completely negative for S-100 protein, smooth muscle actin, desmin, CD34, the estrogen receptor and p16. The Ki-67 labeling index was low (1.25%). Ultrastructurally, the neoplastic cells had numerous premelanosomes with some glycogen deposits. Single-stranded DNA conformational polymorphism of p53 and methylation-specific polymerase chain reaction of p16 revealed negative results. Definite melanosomes on electron microscopic analysis and coexpression of HMB45 antigen and stem cell factor receptor (CD117) may provide the clue to understanding perivascular epithelioid cell tumor because angiomyolipoma also coexpresses HMB45 antigen and CD117.     

Infrequent SMARCB1/INI1 gene alteration in epithelioid sarcoma: a useful tool in distinguishing epithelioid sarcoma from malignant rhabdoid tumor

Loss of SMARCB1/INI1 protein expression is considered useful for confirming a histologic diagnosis of malignant rhabdoid tumor. However, loss of SMARCB1/INI1 protein expression has recently been reported in other tumors as well, including a few cases of epithelioid sarcoma. In addition, the histopathologic differences between proximal-type epithelioid sarcoma and malignant rhabdoid tumor have not been conclusively defined. We analyzed SMARCB1/INI1 protein expression in 54 epithelioid sarcoma (proximal-type, 25; distal-type, 29) and examined alterations of the SMARCB1/INI1 gene in the cases lacking protein expression. We found that 19 (76.0%) proximal-type epithelioid sarcoma and 27 (93.1%) distal-type epithelioid sarcoma showed loss of SMARCB1/INI1 protein expression. Analysis of 39 cases with loss of protein expression revealed 4 cases (10.3%) with SMARCB1/INI1 gene alterations at the DNA level (homozygous deletion, 2; 1- or 2-bp deletion, 2) that could have induced the loss of gene products, and all 4 of these were proximal-type epithelioid sarcoma. Epithelioid sarcoma was thus associated with a high frequency of loss of SMARCB1/INI1 protein expression similar to that in malignant rhabdoid tumor. However, the frequency of SMARCB1/INI1 gene alteration at the DNA level in proximal-type epithelioid sarcoma was significantly lower than that in malignant rhabdoid tumor. In addition, the prognosis of patients with malignant rhabdoid tumor is significantly worse than that of patients with proximal-type epithelioid sarcoma (P = .001). Therefore, proximal-type epithelioid sarcoma and malignant rhabdoid tumor are suggested to be distinctive tumors with respect to the mechanism of the loss of SMARCB1/INI1 protein expression. Analysis of alterations in the SMARCB1/INI1 gene may thus be a useful diagnostic tool to distinguish proximal-type epithelioid sarcoma from malignant rhabdoid tumor.     

Renal epithelioid angiomyolipoma--a close mimic of renal cell carcinoma. Report of a case and review of the literature

The epithelioid variant of angiomyolipoma (EAML) is a rare tumor of unpredictable behavior that is composed of epithelioid, spindle, and giant cells and contains no or only a minimal amount of lipomatous tissue. The picture can lead to an erroneous diagnosis of renal cell carcinoma or sarcoma. We report on a case of EAML in the kidney of a 47-year-old female without any signs of tuberous sclerosis and review the literature. Grossly, a well-demarcated, spheroid, largely hemorrhagic tumor measuring 4.2 cm in diameter occupied the central third of the kidney. Histologically, it was solid, highly cellular, with occasional microcysts, composed of medium to large epithelioid cells with clear or oxyphilic cytoplasm, short spindle cells, and numerous giant multinucleated cells. After extensive sampling, adult-appearing fat tissue was found to present as rare foci of microscopic dimensions. Immunohistochemically, the tumor cells showed positive reactions with antibodies against HMB-45, melan A, CD-68, muscle-specific actin, and, rarely, smooth muscle actin. Cytokeratins and epithelial membrane antigen were negative. The EAML is a variant growing in a carcinoma-like pattern that can lead to an erroneous diagnosis of renal cell carcinoma. An extensive sampling and HMB-45 and CD-68 positivity combined with cytokeratin negativity are of paramount importance for the correct diagnosis. As a sporadic renal tumor it followed a benign course in most of the reported cases.     

Diffuse intra-abdominal clear cell myomelanocytic tumor: report of an unusual presentation of "PEComatosis" simulating peritoneal mesothelioma

We report a case of diffuse myomelanocytic tumor of the peritoneum that simulates, clinically and instrumentally, a malignant mesothelioma. The patient was a 70-year-old woman with a history of ancient hysterectomy for fibroids, who presented with abdominal discomfort. Exploratory laparotomy revealed diffuse encasing of the peritonealized organs by a thin, fleshy, gray-white tissue rind. Scattered tumor masses were present as well. A dominant lesion measuring 6 cm in larger size was resected from the pelvis. Histological examination revealed a tumor composed of epithelioid and spindle cells, exhibiting either a clear or slightly eosinophilic cytoplasm and a mild to moderate nuclear pleomorphism. Focal areas of necrosis could be documented. Immunohistochemically, tumor cells were positive for HMB45, melan-A, and smooth muscle actin, but negative for other antibodies, including epithelial markers, desmin, and S100 protein. We believe that this case represents an example of myomelanocytic tumor of uncertain biologic potential, a member of the recently devised perivascular epithelioid cell tumors (PEComa), with an unusual presentation simulating a diffuse mesothelial neoplasm. The origin of this particular lesion is briefly discussed in light of the recent literature published on the subject.     

A hepatic tumor associated with bilateral renal angiomyolipomas: A variant of angiomyolipoma?

Angiomyolipoma is usually derived from the kidney and composed of well developed vessels, smooth muscle and fat tissue. The liver is the only extra-renal site of angiomyolipoma. A peculiar type of hepatic tumor accompanied by bilateral renal angiomyolipomas is reported here. The tumor was mostly composed of large epithelioid cells and a small part of hyalinized large vessels and foam cell infiltration. Mature adipose tissue was absolutely absent. Epithelioid tumor cells arranged in an alveolar pattern had abundant glycogen and some diastase-resistant periodic acid-Schiff granules without obvious crystals. Immunohistochemical studies revealed that the epithelioid cells were positive for melanoma specific antibody (HMB-45), S-100 protein, aromatic L-amino acid decarboxylase and focally a-smooth muscle actin. Many melanosome- or premelanosome-like, electron-dense granules were observed in these cells. Thus, these cells were characterized by differentiation to both immature melanocytes and smooth muscle ceils. These epithelioid cells were similar to some cells in the renal angiomyolipomas of the same patient. The hepatic tumor was considered to be a result of monotonous proliferation of the epithelioid cells seen in renal angiomyolipoma. Differential diagnosis of this tumor was discussed.     

Perivascular epithelioid cell tumor (PEComa) of the pancreas: Immunoelectron microscopy and review of the literature

A perivascular epithelioid tumor (PEComa) is a rare tumor probably arising from the perivascular epithelioid cells. Only three cases of pancreatic PEComa have been reported in the English-language literature. The present report describes an extremely rare case of pancreatic PEComa. A 47-year-old Japanese woman complained of lower abdominal pain and a well-demarcated solid tumor was found in the pancreatic head. There was no history of tuberous sclerosis complexes. Pylorus-preserving pancreaticoduodenectomy was thus performed. There was a well-demarcated, solid tumor measuring 17 mm in the pancreatic head. The tumor was composed of a diffuse proliferation of epithelioid tumor cells with many blood vessels but no adipose tissue. The tumor cells expressed HMB45 and α-smooth muscle actin. Ultrastructurally, the tumor cells possessed many membrane-bound granules that were positive for HMB45 on immunoelectron microscopy. The results of immunoelectron microscopy show that some PEComas possess not only typical melanosomes or premelanosomes but also aberrant melanosomes.     

Atypical pleomorphic epithelioid angiomyolipoma localized to the pelvis: a case report and review of the literature

AIMS: Angiomyolipoma is the most common mesenchymal tumour of the kidney. It has been reported in several other sites outside the kidney, mainly in the liver. We report the first case of atypical pleomorphic angiomyolipoma in a man, arising from the pouch of Douglas and extending to the entire abdominal cavity. METHODS: A 17-year-old man underwent a complete resection of a giant abdominopelvic mass. The tissue was formalin fixed and paraffin embedded and 4 micro m thick histological sections were stained with haematoxylin-eosin. Immunohistochemical stains for HMB-45, smooth muscle actin, vimentin, calponin, S100 and desmin were performed. Sections for electron microscopy were also prepared. RESULTS: Microscopic examination revealed a neoplasm composed of pleomorphic epithelioid cells with atypical features, immunoreactive for HMB-45, MART-1, actin, vimentin and calponin, while S100 protein and desmin stains were negative. Ultrastructurally, the tumour cells showed prominent nucleoli, vacuolated cytoplasm, and some premelanosomes. A diagnosis of atypical pleomorphic epithelioid angiomyolipoma was then made. CONCLUSIONS: To date five patients with abdominal epithelioid angiomyolipoma have been described in the literature. All were women. Three of the five patients reported developed metastasis, while our patient is still free of disease at 16 months of follow-up. Clear prognostic pathological features have not been identified.