Hepatic angiomyolipoma

Hepatic angiomyolipoma is a rare, benign, hepatic mesenchymal neoplasm found in both males and females, and most commonly in adult females. Angiomyolipoma occurs most commonly in the kidneys. The liver represents the second most frequent site of involvement. Hepatic angiomyolipomas are composed of varying amounts of smooth muscle cells, adipose tissue, and vessels. The smooth muscle cell component is the most specific to the diagnosis. The smooth muscle cells can have varying morphologies and are positive for homatropine methylbromide-45 but are negative for hepatocyte paraffin 1 and S100 protein. The definitive diagnostic study remains the histologic examination of the surgically resected lesion coupled with immunohistochemical stains. The differential diagnosis includes hepatocellular carcinoma, hepatic adenoma, leiomyoma, hepatoblastoma, melanoma, and gastrointestinal stromal tumor. The immunohistochemical staining pattern differentiates this lesion from other malignant and benign liver lesions. If the diagnosis of hepatic angiomyolipoma has been made, it can be followed conservatively or surgically resected.     

Angiomyolipoma of the large intestine: report of a case.

A case of an angiomyolipoma of the large intestine occurring in a 55-year-old man without evidence of tuberous sclerosis is reported. Endoscopically, the lesion resembled a sessile adenomatous polyp. The tumor measured 1 cm. Histologic examination revealed a lesion composed predominantly of spindle and epithelioid cells with significant nuclear atypia. Mitoses were rare. The tumor was strongly positive for HMB-45, CD68, vimentin, desmin, and smooth muscle actin. Rare scattered cells reacted with CD34. No residual tumor was found in the resected colon.     

Fat-predominant mixed epithelial stromal tumor (MEST): report of a unique case mimicking angiomyolipoma

A unique case of a mixed epithelial stromal tumor (MEST) that was predominantly composed of adipose tissue is reported here. Radiographically and grossly, the lesion was thought to be an angiomyolipoma, based upon its fatty appearance. Microscopically, the lesion was predominantly composed of mature adipose tissue but also contained clusters of bland tubules surrounded by smooth muscle bundles and collagen. By immunohistochemistry, the stroma labeled diffusely for estrogen and progesterone receptors, while the muscle bundles labeled for desmin. Melanocytic markers HMB45 and Melan A, typically positive in angiomyolipoma, were nonreactive. This case expands the morphologic spectrum of MEST to include mimics of angiomyolipoma.     

Angiomyolipoma of the anterior mediastinum

Angiomyolipoma is a benign tumor composed of varying proportions of smooth muscle cells, blood vessels, and adipose tissue that most commonly occurs in the kidney. Sporadic lesions and lesions arising in the setting of the tuberous sclerosis complex have been reported in extrarenal sites. We present the case of an incidentally discovered angiomyolipoma in the anterior mediastinum. Thymoma was suspected clinically, and the lesion was composed mainly of spindled-to-epithelioid cells arranged in a histologic pattern reminiscent of hemangiopericytoma, a pattern that has been described in thymoma. Immunohistochemical stains revealed positivity for smooth muscle actin and HMB-45, revealing the expression of smooth muscle and melanocytic markers characteristic of angiomyolipoma and other lesions in the PEComa family.     

肾上皮样血管平滑肌脂肪瘤肺转移1例报告并文献复习

目的：探讨肾上皮样血管平滑肌脂肪瘤病理特点及生物学行为。方法：对1例低热患者行肺肿块穿刺活检,然后行HE染色和免疫组织化学染色。复习肾肿瘤病理切片并进行文献复习。结果：穿刺活检病理分析：密集分布的上皮样细胞,细胞体积大,呈圆形、多边形;异型明显;无血管平滑肌脂肪瘤结构;免疫组织化学：人黑色素瘤蛋白阳性,平滑肌肌动蛋白阳性,上皮膜抗原阴性。病理诊断：左肺上皮样血管平滑肌脂肪瘤;考虑来源于肾。结论：上皮样血管平滑肌脂肪瘤是一种有恶性潜能的间叶性肿瘤,可以发生远处转移。     

Renal angiomyolipoma with a clear cell component

Case report of a 52-year-old woman with angiomyolipoma of the left kidney. The tumor had appearance of a typical angiomyolipoma predominantly composed of spindle cells, some epithelioid cells and few large hyalinized vessels. Adipose tissue was concentrated into small foci. Unusual presence of large cells with a clear fine granular cytoplasm closely resembled cells of the "sugar tumor" of the lung. Epithelioid cells and occasionally spindle cells were HMB45 positive. A minority of cells also coexpressed S100 protein. Clear cells were usually strongly positive for HMB45 too. Our findings supported consideration of a close relation between clear cell ("sugar") tumor of the lung and angiomyolipoma.     

Monotypic angiomyolipoma of the nasal cavity: a heretofore undescribed occurrence

A monotypic angiomyolipoma of the nasal cavity in a 34-year-old woman is described. Tumor cells were spindled or epithelioid and contained glycogen and diastase-resistant PAS-positive granules. There were few mitoses, and necrosis was absent, indicating a benign tumor. The stroma was markedly vascular, and a few adipocytes were seen in one area. Cells were positive for melanocyte and muscle markers. Electron microscopy revealed abundant dense granules. Although melanin was absent histochemically, it was present using a chemical assay, and the granules may, therefore, be atypical melanosomes. Fine actin filaments, attachment plaques and lamina were present. Initial assessment of the lesion indicated malignant melanoma, but the immunostaining and histologic features indicated monotypic angiomyolipoma. To the best of our knowledge, this is the first such case in the nasal cavity.     

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.     

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.     

Angiomyolipoma of the liver and lung: a case explained by the presence of perivascular epithelioid cells

We report a case of synchronous hepatic and pulmonary angiomyolipoma not associated with tuberous sclerosis or renal angiomyolipoma. The liver tumor contained tortuous vessels, smooth muscle tissue, and fat. It was partially necrotic and made up of pleomorphic epithelioid smooth muscle cells. Positivity for HMB-45 confirmed the diagnosis of angiomyolipoma. Lung biopsy showed multiple abnormal proliferation of smooth muscle cells exhibiting spindle-shaped or epithelioid morphology. The tumor grew around the vessels, and the cells were positive for HMB-45. The occurrence of this case could be explained by a simultaneous proliferation of perivascular epithelioid cells. To the best of our knowledge, this is the first case of hepatic angiomyolipoma associated with multiple pulmonary angiomyolipomas, mimicking hepatic tumor lung metastases on X-ray examination.     

Epithelioid angiomyolipoma: a morphologically distinct variant that mimics a variety of intra-abdominal neoplasms

This review examines the histopathologic, immunohistochemical, ultrastructural, and molecular biologic features of epithelioid angiomyolipoma (EAML), with an emphasis on the differential diagnosis of intra-abdominal EAML. Epithelioid angiomyolipoma is an uncommon mesenchymal tumor with malignant potential, frequently associated with tuberous sclerosis complex. Histologically, EAML is characterized by sheets or nests of large polygonal epithelioid cells with abundant eosinophilic or occasionally clear cytoplasm, often with prominent nucleoli, and EAML may include multinucleated and markedly pleomorphic forms. As these tumors share a distinctive perivascular epithelioid cell phenotype, they belong to the PEComa tumor family. Nearly all EAMLs show immunoreactivity for both melanocytic and myoid markers. Ultrastructurally, EAMLs show evidence of melanogenesis by the presence of premelanosomes. Epithelioid angiomyolipoma can pose significant diagnostic challenges as it mimics morphologically a variety of neoplasms including renal cell carcinoma, renal oncocytoma, adrenal cortical neoplasm, epithelioid smooth muscle tumor, epithelioid peripheral nerve sheath tumor, epithelioid gastrointestinal stromal tumor, epithelioid melanoma, hepatoblastoma, and hepatocellular carcinoma. The variation in immunophenotype in these tumors requires a prudent use of immunohistochemistry, which may occasionally need complementation by electron microscopy to establish the correct diagnosis.     

Hepatic angiomyolipoma: report of two cases with emphasis on smear cytomorphology and the use of cell block with immunohistochemical stains

Angiomyolipoma is a benign mesenchymal lesion that occurs most commonly in the kidney. Its occurrence in the liver is relatively rare. We report two cases of hepatic angiomyolipoma diagnosed by ultrasound-guided, needle aspiration biopsy. One of the patients was a previously healthy 62-yr-old woman who presented with a hepatic mass incidentally during a healthy examination. The other patient was a 67-yr-old man, a victim of chronic hepatitis C, who was found to have a hepatic tumor in the right lobe during regular follow-up. Cytologic preparations of the two hepatic masses showed some mature adipocytes admixed with clusters of variable-sized mesenchyme-like cells with fibrillar cytoplasm and indistinct cytoplasmic borders. Some of the cells were round to oval and others were spindle shaped with oval, cigar-shaped or elongated nuclei. The nuclear chromatin was fine and some cells showed round nucleoli. No thick-walled blood vessels were noted in the cytological smears. In the cell block preparations, a mixture of thick-walled blood vessels, mature adipose tissue, and bundles of variable-sized smooth muscle cells were noted. The spindle or epithelioid smooth muscle cells were positive for vimentin, alpha-smooth muscle actin, and human melanoma black (HMB)-45 but negative for desmin and S100 protein in immunohistochemical stains. The purpose of the current study is to describe cytological features of this lesion with differential diagnosis because pathologists may be called on to render a diagnosis on needle aspiration. HMB-45 has been proved to be a sensitive marker for the smooth muscle component of angiomyolipoma. Cell block preparations assisted with immunohistochemical staining should be emphasized for definite diagnosis. Although a surgical procedure may still be necessary once a diagnosis of angiomyolipoma is made, treatment may be tailored for a less aggressive procedure than for malignant hepatic nodules.     

Hepatic angiomyolipoma. A case report with review of the literature

Hepatic angiomyolipoma in a 59-year-old woman is reported. The tumor was located at the lower edge of the left lobe of the liver, measured 3 x 2 x 2 cm, and appeared solid. Histologically, it consisted of abundant blood vessels of varying caliber, mature fat cells, and round, spindle-shaped or epithelioid interstitial cells. The latter were considered to be of smooth muscle origin, because myofilamentous structures were demonstrated ultrastructurally in the cytoplasm and because they were positive for desmin by the PAP method. Based on these findings, the diagnosis of angiomyolipoma was confirmed. A review of the literature revealed only 15 cases of hepatic angiomyolipoma. From a clinicopathological viewpoint, a comparison was made between hepatic angiomyolipoma and its more frequent renal counterpart. The hepatic tumor is considered to be a kind of hamartoma.     

HEPATIC ANGIOMYOLIPOMA

Hepatic angiomyolipoma in a 59-year-old woman Is reported. The tumor was located at the lower edge of the left lobe of the liver, measured 3 × 2 × 2 cm, and appeared solid. Histologically, It consisted of abundant blood vessels of varying caliber, mature fat cells, and round, spindle-shaped or epithelioid interstitial cells. The latter were considered to be of smooth muscle origin, because myofilamentous structures were demonstrated ultrastructurally in the cytoplasm and because they were positive for desmin by the PAP method. Based on these findings, the diagnosis of angiomyolipoma was confirmed. A review of the literature revealed only 15 cases of hepatic angiomyolipoma. From a clinlcopathological viewpoint, a comparison was made between hepatic angiomyolipoma and its more frequent renal counterpart. The hepatic tumor is considered to be a kind of hamartoma.     

Pleomorphic Angiomyolipoma of Digestive Tract: A Heretofore Unrecognized Entity

Two cases of pleomorphic angiomyolipoma (AML) composed of bizarre epithelioid smooth muscle cells located in the gastrointestinal tract are reported. One involved the appendix of a 6-year-old girl, and the second the cecum of a 22-year-old woman. In both instances the tumor cells were immunoreactive for HMB-45 and A103. To the best of our knowledge, this peculiar variant of an AML has not previously been recognized in this location. Int J Surg Pathol 8(1):67-72, 2000     

Fat-forming solitary fibrous tumor of the kidney: a case report and literature review

Fat-forming solitary fibrous tumor (SFT) is a rare soft tissue tumor. Herein, we reported a 30-year-old woman was found to have a solid mass measuring 60×45 mm in the right kidney on an abdominal computed tomography scan. The tumor was well-circumscribed and composed of cellular nodules with the classic SFT admixed with clusters and lobules of mature adipocytes. Immunohistochemistry staining showed that the tumor cells were diffusely and strongly positive for CD34 and Bcl-2, focally and weakly positive for CD99 and EMA. Mature adipocytes were positive for S-100 protein. Ki-67 expression was found in approximately 2% of tumor cells. However, tumor cells were negative for cytokeratin, S-100 protein, HMB-45, Melan-A, SMA, and CD117. We made the pathological diagnosis of fat-forming SFT of the right kidney. The differential diagnosis includes angiomyolipoma, liposarcoma, spindle cell lipoma, sarcomatoid renal cell carcinoma, synovial sarcoma, and gastrointestinal stromal tumor. The patient was alive and well without evidence of recurrence or metastasis at 19 months after tumor resection.     

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.     

Retroperitoneal lipomatous angiomyolipoma associated with amyloid deposition masquerading as well-differentiated liposarcoma

Reported herein is a case of retroperitoneal angiomyolipoma associated with amyloid deposition, masquerading as well-differentiated liposarcoma. A 16 x 13 cm lipomatous tumor was resected from the perirenal retroperitoneum of a 71-year-old woman. Microscopically, the tumor was exclusively composed of mature adipose tissue and abnormal thick blood vessels, but bundles of smooth muscle were lacking. In addition, amyloid was deposited between fat cells. Initially, well-differentiated liposarcoma was highly suspected. However, there were a few epithelioid cells with clear vacuolated cytoplasm within the vessel walls, which were immunoreactive for smooth muscle markers and HMB-45. Real-time polymerase chain reaction failed to demonstrate the amplification of the murine double-minute type 2 gene and cyclin-dependent kinase 4 gene in this tumor. Therefore, the tumor was diagnosed as lipomatous angiomyolipoma. After the diagnosis, it was found that the patient had multiple myeloma and cardiac amyloidosis, suggesting that the amyloid deposition within the tumor was a complication of the myeloma. Lipomatous angiomyolipoma may be a diagnostic pitfall of retroperitoneal lipomatous tumors.     

Angiomyolipom der Lunge

We present a case of a 48 year old man who complained of progressive dyspnoea. Radiograph revealed a large tumor in the left lung. Biopsy was performed and revealed beneath a normal bronchial epithelium polymorph tumor cells admixed with some histiocytes. These tumor cells were strongly pigmented and expressed HMB-45 and protein S-100 immunohistochemically. Malignant melanoma of the bronchus was included in the differential diagnosis. A thoracotomy and left lower lobe resection was performed. Histology revealed an angiomyolipoma. The lung is an uncommon localisation of angiomyolipoma with so far three reported cases. Lipoma, leiomyoma and lymphangioleiomyomatosis have to be included in the differential diagnosis. The peculiarity of this case is the presence of multiple pigmented tumor cells that express HMB-45. This has not been reported yet.     

肾血管平滑肌脂肪瘤31例临床病理分析

目的：探讨肾血管平滑肌脂肪瘤（angiomyolipoma，AML）的临床病理特征。方法：对31例肾AML的临床病理特征进行分析，并做免疫组化检测，其中4例做电镜观察。结果：31例肾AML按其组织形态可分为典型型（67.7%）、非典型型(6.5%)、平滑肌瘤样型（9.7%）、脂肪瘤样型（9.7%）、炎症型（6.5%）5型。免疫表型：肿瘤细胞特征性表达HMB45、Melan-A、gp-100、HHF35、SMA、CD68。其中1例电镜下肿细胞内可见黑色素小体。结论：肾AML的组织形态多样，特征性免疫级化标记为诊断提供依据。掌握形态特征及其鉴别诊断要点有助于临床的正确治疗。