Malignant transformation of renal angiomyolipoma

Epithelioid angiomyolipoma of the pancreas: A case report and review of the literature

BACKGROUND

Angiomyolipomas (AMLs), belonging to the family of mesenchymal tumors, are considered benign lesions that occur mostly in the kidney or as a part of tuberous sclerosis. Epithelioid AML (EAML) is a rare type of AML that appears to have malignant potential. Extrarenal AMLs usually occur in the liver according to the retrieved literature reports. There have been only two previous reports of monofocal primary AML of the pancreas; however, no cases of primary monotypic EAML of the pancreas have been reported.

CASE SUMMARY

An asymptomatic 59-year-old woman incidentally revealed a tumor during abdominal ultrasound examination. Routine blood tests and physical examination were within normal limits. Abdominal ultrasound revealed a 1.9-cm hypoechogenic mass in the tail of the pancreas, clearly visualized by endoscopic ultrasound. However, contrast-enhanced abdominal computed tomography scans did not demonstrate the lesion. A subsequent gadolinium-enhanced magnetic resonance imaging scan showed that the lesion had some characteristic manifestations. The lesion was initially thought to be a neuroendocrine tumor (asymptomatic PanNET). After surgical resection, histopathology and immunohistochemistry confirmed the diagnosis of EAML. At the 6-mo follow-up, no recurrence, spread, or metastasis was identified on computed tomography or magnetic resonance imaging.

CONCLUSION

The preoperative diagnosis of pancreatic AML is extremely difficult. Imaging techniques are essential for providing valuable morphological features for differential diagnosis.

A large bi-lobed classic renal angiomyolipoma with vena caval extension

Renal angiomyolipomas (AMLs) are the most common benign renal tumors encountered, and composed of 3 components: mature adipose tissues, smooth muscles, and blood vessels. Mostly asymptomatic and discovered incidentally, the classic type of AMLs rarely extend to involve great vessels. Radiological confirmation of such lesions is paramount for diagnosis and planned intervention. Management of AMLs is based on clinical presentation and varies from active surveillance to invasive surgical interventions. A case of sizeable classic AML with extension to inferior vena cava is presented here, with successful tumor resection performed after complete liver mobilization. A literature review and a summary of similar cases are also presented. A multidisciplinary approach is required for proper and precise radiological diagnosis to achieve an adequate surgical resection, which might sometimes be complicated and complex, as in this current case.

Update on the Diagnosis and Management of Renal Angiomyolipoma

PURPOSE

Advances in minimally invasive therapies and novel targeted chemotherapeutics have provided a breadth of options for the management of renal masses. Management of renal angiomyolipoma has not been reviewed in a comprehensive fashion in more than a decade. We provide an updated review of the current diagnosis and management strategies for renal angiomyolipoma.

MATERIALS AND METHODS

We conducted a PubMed(®) search of all available literature for renal or kidney angiomyolipoma. Further sources were identified in the reference lists of identified articles. We specifically reviewed case series of partial nephrectomy, selective arterial embolization and ablative therapies as well as trials of mTOR inhibitors for angiomyolipoma from 1999 to 2014.

RESULTS

Renal angiomyolipoma is an uncommon benign renal tumor. Although associated with tuberous sclerosis complex, these tumors occur sporadically. Risk of life threatening hemorrhage is the main clinical concern. Due to the fat content, angiomyolipomas are generally readily identifiable on computerized tomography and magnetic resonance imaging. However, fat poor angiomyolipoma can present a diagnostic challenge. Novel research suggests that various strategies using magnetic resonance imaging, including chemical shift magnetic resonance imaging, have the potential to differentiate fat poor angiomyolipoma from renal cell carcinoma. Active surveillance is the accepted management for small asymptomatic masses. Generally, symptomatic masses and masses greater than 4 cm should be treated. However, other relative indications may apply. Options for treatment have traditionally included radical and partial nephrectomy, selective arterial embolization and ablative therapies, including cryoablation and radio frequency ablation, all of which we review and update. We also review recent advances in the medical treatment of patients with tuberous sclerosis complex associated angiomyolipomas with mTOR inhibitors. Specifically trials of everolimus for patients with tuberous sclerosis complex suggest that this agent may be safe and effective in treating angiomyolipoma tumor burden. A schema for the suggested management of renal angiomyolipoma is provided.

CONCLUSIONS

Appropriately selected cases of renal angiomyolipoma can be managed by active surveillance. For those patients requiring treatment nephron sparing approaches, including partial nephrectomy and selective arterial embolization, are preferred options. For those with tuberous sclerosis complex mTOR inhibitors may represent a viable approach to control tumor burden while conserving renal parenchyma.

PEComa: morphology and genetics of a complex tumor family

Perivascular epithelioid cell tumors, or PEComas, are mesenchymal neoplasms composed of histologically and immunohistochemically distinctive epithelioid or spindle cells, which are immunoreactive for both smooth muscle and melanocytic markers. The cells in PEComas are typically arranged around blood vessels and appear to form the vessel wall, often infiltrating the smooth muscle of small- to medium-sized vessels. Periluminal cells are usually epithelioid and the more peripheral cells are spindle shaped. The cells have small, round to oval nuclei, sometimes with focal nuclear atypia, and clear to eosinophilic cytoplasm, and no counterpart normal cell has been identified. The PEComa "family" now includes angiomyolipoma, pulmonary clear cell "sugar" tumor and lymphangioleiomyomatosis, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, abdominopelvic sarcoma of perivascular epithelioid cells, and other tumors with similar features at various sites that are simply termed PEComa. Some PEComas occur in patients with tuberous sclerosis complex and share the genetic abnormalities. There is a behavioral spectrum from benign to frankly malignant, and histologic criteria have been proposed for assessing malignant potential. The differential diagnosis can include carcinomas, smooth muscle tumors, other clear cell neoplasms, and adipocytic tumors. PEComas constitute a genetically diverse group that includes neoplasms harboring TFE3 gene rearrangements and those with TSC2 mutations, indicating alternative tumorigenic pathways. Recent advances in therapy of malignant PEComas relate to increased knowledge of specific genetic changes and their effects on metabolic pathways that are susceptible to specific interventions. We review PEComas, emphasizing the diagnostic spectrum and recent immunohistochemical and genetic findings.

Angiomyolipoma

Angiomyolipomas are the most common benign tumor of the kidney and can be found in up to 1% of the general population.

Aggressive renal angiomyolipoma with vena cava extension: A case report and literature review

Renal angiomyolipoma (AML) is the most common type of benign mesenchymal tumor of the kidney. AMLs typically present as benign lesions without local invasion. However, the tumor may exhibit aggressive behavior. Intravascular extension into the inferior vena cava (IVC) and hemorrhagic aneurysm formation associated with AML has rarely been reported in the past. In the current study, the novel case of a 77-year-old female is described who presented with a tumor thrombus extending to the IVC. The patient subsequently underwent a radical nephrectomy and an IVC tumor thrombectomy. In addition, the available literature regarding this unusual complication of a common renal neoplasm has been reviewed. It is essential for radiologists and clinicians to be aware that AMLs may exhibit these types of aggressive behaviors.

Nephron sparing surgery for renal angiomyolipoma with inferior vena cava thrombus in tuberous sclerosis

Introduction. Angiomyolipoma is a common benign renal tumor. It is associated with Tuberous Sclerosis Complex (TSC) in 20% of patients. Angiomyolipomas are classically multiple, bilateral, and growing; they may lead to complications such as Wunderlich syndrome or, in rare cases, to venous extension. Observation. a 74-year-old woman with TSC presented with an angiomyolipoma of the right kidney with inferior vena cava (IVC) fatty thrombus. She underwent partial nephrectomy and thrombectomy. After a 7-year follow-up there was no evidence of recurrence or metastasis and her renal function was preserved. Review of Literature. It is the 44th reported angiomyolipoma associated with IVC thrombus. The mean size of angiomyolipomas was 86.1 mm and 67.4% of patients were symptomatic. Pulmonary embolism was found in 6 patients. There were 2 cases of recurrence/metastatic outcome after radical nephrectomy and thrombectomy. They were associated with epithelioid form. The mean size of epithelioid tumors was significantly bigger than in classical angiomyolipomas (127.1 mm versus 82.6 mm, P = 0.037). With a median follow-up of 12 months, 91.3% of patients were recurrence and metastasis free, with 3 cases of nephron sparing surgery. Conclusion. Nephron sparing surgery for angiomyolipoma with IVC fatty thrombus can be safely performed in TSC, even in sporadic angiomyolipoma.

Malignant renal angiomyolipoma with metastases in a child

The biological character of epithelioid angiomyolipoma (EAML) remains controversial and little is known about EAML in children. We present a case of a 7-year-old boy with abdominal distention, diagnosed as EAML. Under microscopy, epithelioid cells were observed, with eosinophilic or slightly eosinophilic cytoplasm and nuclear pleomorphism, thick-walled blood vessels, and some cells that were differentiated to smooth muscle cells or fat cells were easily observed. Immunochemical staining showed that Melan-A and HMB45 were positive. The tumor presented highly aggressive biobehavior. Furthermore, we reviewed and analyzed cases of diagnosed EAML in our hospital and those reported in the literature. Renal EAML (10/17) was most common, and the EAML of 3 of 17 patients metastasized to other organs.

[Renal angiomyolipoma with inferior vena cava extension]

Angiomyolipoma is generally a benign and noninvasive tumor. We report a case of angiomyolipoma with tumor thrombus from the renal vein into the inferior vena cava suggesting a malignant disease.

Malignant epithelioid angiomyolipoma in the kidney and liver of a patient with pulmonary lymphangioleiomyomatosis: lack of response to sirolimus

A 26-year-old woman with lymphangioleiomyomatosis (LAM) was hospitalized for the surgical excision of a giant abdominal tumor of right kidney origin. The pathological diagnosis of the tumor was conventional angiomyolipoma (AML). After 8 months, 2 liver tumors appeared and grew rapidly. The tumors were resected, and the pathological finding of these tumors was epithelioid AML. Thereafter, metastatic multiple lung tumors appeared, and there was local recurrence of the liver tumors. Sirolimus, an mTOR protein inhibitor, was used to treat epithelioid AML. However, the drug did not inhibit the rapid growth of the tumor at all. This finding suggests that sirolimus might not be effective against epithelioid AML, and in such cases, complete surgical resection should be the treatment of choice.

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.

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.

PEComas: the past, the present and the future

The perivascular epithelioid cell (PEC) is a cell type constantly present in a group of tumors called PEComas. PEC expresses myogenic and melanocytic markers, such as HMB45 and actin. Recently, recurrent chromosomal alterations have been demonstrated in PEC. At present, PEComa is a widely accepted entity. In the past 10 years, the use of this term has allowed to report and describe numerous cases permitting to start highlighting the biology of this group of lesions. PEComas are related to the genetic alterations of tuberous sclerosis complex (TSC), an autosomal dominant genetic disease due to losses of TSC1 (9q34) or TSC2 (16p13.3) genes which seem to have a role in the regulation of the Rheb/mTOR/p70S6K pathway. There are some open questions about PEComas regarding its histogenesis, the definition of epithelioid angiomyolipoma and the identification of the histological criteria of malignancy. An innovative therapeutic trial using rapamycin is under way for tumors occurring in TSC such as renal angiomyolipoma and lymphangioleiomyomatosis. Its success could provide the rationale for the use of the same drug in other lesions composed of PECs, especially in the malignant ones.

Clinical presentation of epithelioid angiomyolipoma

OBJECTIVE

Epithelioid angiomyolipomas (AML) of the kidney are malignant tumors with aggressive clinical behavior.

METHODS

We reviewed cases of epithelioid AML recently diagnosed at our institution to highlight the spectrum of clinical presentations.

RESULTS

In all cases, renal lesions seen on computed tomography were suspicious for renal cell carcinoma (RCC). Histologically, these tumors can resemble RCC. The diagnosis of epithelioid AML was established by positive staining for melanoma and smooth muscle cell markers, and presence of perivascular epithelioid cells. One patient presented with a renal tumor extending into the inferior vena cava to the level of the hepatic veins. Two patients developed recurrent, metastatic disease following nephrectomy. One patient with tuberous sclerosis and multiple, bilateral AML developed an enhancing renal tumor that did not contain any fat densities. A partial nephrectomy was performed and pathology revealed epithelioid AML adjacent to conventional AML.

CONCLUSIONS

These tumors are distinguished from RCC by positive immunostaining for melanoma markers and smooth muscle cell markers. They resemble conventional RCC on imaging. Epithelioid AML may be locally aggressive and metastasize.

Fat poor renal angiomyolipoma: patient, computerized tomography and histological findings

PURPOSE

We reviewed our experience with fat poor cases of angiomyolipoma.

MATERIALS AND METHODS

The records of patients with angiomyolipoma, as determined by pathological study, from 1998 to 2004 were reviewed by recording patient demographics and outcomes. Fat poor cases were defined as the failure of imaging to demonstrate fat in a lesion. Computerized tomography and histological characteristics were assessed.

RESULTS

Histologically confirmed angiomyolipoma was found in 15 patients. Multiple lesions were found in 3 of 15 cases (20%). Of these 15 patients who underwent surgery 11 (73%) had unsuspected angiomyolipoma due to absent fat on computerized tomography and they underwent intervention for presumed renal cell carcinoma. Mean age +/- SD in this group was 54 +/- 15 years and 8 of 11 patients (73%) were female, of whom 4 (50%) had uterine fibroids. These lesions were found incidentally in 7 of 11 cases (64%). Operative complications developed in 2 of 11 patients (18%). Average maximal diameter on pathological evaluation was 3.2 +/- 1.3 cm (range 1.5 to 6). Nonenhanced computerized tomography was available in 7 of 11 cases, of which 3 of 7 (42%) showed hyperdense lesions and 4 of 7 (57%) showed isodense lesions. The percent of fat identified per high power field was less than 25% in 12 of 13 fat poor angiomyolipoma lesions (92%) compared to 2 of 4 classic lesions (50%) known to be angiomyolipoma before surgery (p = 0.04).

CONCLUSIONS

We suggest that a general definition of fat poor angiomyolipoma should be the failure of imaging to reveal fat within a lesion, thus, making it unsuspected at surgery. A pathological definition should be less than 25% fat per high power field, which to our knowledge is a formerly undefined quantity. Not all cases are hyperdense on nonenhanced computerized tomography. These lesions cannot be reliably identified by imaging and they should be managed like all enhancing renal masses.

[Bilateral renal angiomyolipomas with a thrombus in the inferior caval vein. Rare growth pattern of a benign tumor]

Renal angiomyolipomas are mesenchymal tumors that are composed of fat tissue, smooth muscle cells and vessels. These are benign tumors, but in rare cases they show a more aggressive growth pattern with invasion into the venous system but without revealing any signs of malignancy. We report a new case of bilateral renal angiomyolipomas with a caval thrombus in a 36 year old female patient with tuberous sclerosis, and give a brief review of the related literature.

Tubulocystic Carcinoma, Mucinous Tubular and Spindle Cell Carcinoma, and Other Recently Described Rare Renal Tumors

In the past 10 years, several new renal tumors have been identified. Some have been reviewed in this article, and others have been reviewed elsewhere in this issue. Most have been included in the 2004 edition of the WHO classification of tumors of the urinary system and male genital organs. Tubulocystic carcinoma needs to be studied and characterized more fully.

Loss of calponin h1 in renal angiomyolipoma correlates with aggressive clinical behavior

OBJECTIVES

To investigate whether any immunohistochemical differences exist between two types of renal angiomyolipomas (AMLs). Renal AMLs are generally considered to be benign in nature. However, a few of these tumors have been reported to involve other organs.

METHODS

Tissue specimens from 3 cases of clinically aggressive and 9 cases of clinically indolent renal AMLs were examined histologically and immunohistochemically using antibodies against calponin h1 and alpha-smooth muscle actin. Immunostaining was evaluated semiqualitatively as no staining to strong staining.

RESULTS

The tumor cells in the myomatous component of the aggressive type did not show any reaction to the antibody to calponin h1 protein, but they showed strong immunoreactions with the antibody to the alpha-smooth muscle actin antigen. All cases of the nonaggressive AMLs demonstrated strong immunoreactions with both antibodies used.

CONCLUSIONS

Our initial results in a small series of cases suggest a potential molecular difference between the aggressive and nonaggressive type of AMLs. Loss of calponin h1 from the tumor cells of the aggressive type might be related to their pathologically invasive features, and this aggressive type might be categorized into an intermediate type between the benign and malignant types.

Recurrent renal epithelioid angiomyolipoma

Renal angiomyolipoma has traditionally been considered a benign tumor. Recently, a variety of epithelioid angiomyolipomas with malignant potential have been described. We report an adrenal recurrence in a patient who had a cellular angiomyolipoma removed 4 years earlier.

Contemporary diagnosis and management of renal angiomyolipoma

PURPOSE

We present a comprehensive resource that summarizes contemporary advances relevant to the clinical management of renal angiomyolipoma.

MATERIALS AND METHODS

A MEDLINE search was done using the key words angiomyolipoma, hemangioma or lipoma and kidney neoplasm, and therapeutic embolization. References from these articles were reviewed to identify additional relevant source material. We identified 13 series published since 1986 comprising 336 patients as well as 24 reports of therapeutic embolization for angiomyolipoma, comprising 76 patients. To our knowledge we report the largest compilation series to date.

RESULTS

Angiomyolipoma is generally benign, although an uncommon subtype (epithelioid angiomyolipoma) may behave more aggressively. Tuberous sclerosis associated angiomyolipoma tends to be larger, multiple and more likely to cause spontaneous hemorrhage than the sporadic entity. Tumors that hemorrhage tend to be larger. Computerized tomography or magnetic resonance is usually sufficient for diagnosis. Biopsy is rarely useful. Primary indications for intervention include symptoms such as pain or bleeding or suspicion of malignancy. Prophylactic intervention is justifiable for large tumors, in females of childbearing age or in patients in whom followup or access to emergency care may be inadequate. Recent advances that have affected management include improved understanding of tuberous sclerosis complex and angiomyolipoma genetics, the identification of molecular markers that facilitate histopathological diagnosis, and the refinement of embolization and partial nephrectomy techniques.

CONCLUSIONS

Although some cases of angiomyolipoma may require complete nephrectomy, most can be managed by conservative nephron sparing approaches. Ongoing research into the molecular biology and clinical behavior of angiomyolipoma may improve our ability to manage these lesions.

Malignant transformation of renal angiomyolipoma: a case report

We report a case of renal angiomyolipoma (AML) with malignant transformation. A 28-year-old woman developed large bilateral renal masses 5 months before admission to our hospital. She was diagnosed with tuberous sclerosis when she was 4 years old. Total nephrectomy of the left kidney was performed, but she died during the operation. Although the focal region of the resected tumor had the appearance of a classic AML, most of the lesion showed a diffuse proliferation of atypical epithelioid cells resembling that in renal cell carcinoma. The epithelioid cells had extremely pleomorphic and hyperchromatic nuclei with frequent mitotic figures, including atypical forms. Immunohistochemical analysis revealed that the atypical epithelioid cells and the typical AML lesions were both positive for HMB-45 but that the former were negative for epithelial and myogenic markers. The smooth muscle cells and thick-walled vessels were focally positive for muscle-specific actins. Furthermore, the atypical epithelioid cells were immunoreactive for p53, whereas the foci of the typical AML were negative. Examination of the microdissected paraffin-embedded tissues revealed p53 mutations in the malignant epithelioid areas in AML but not in the renal parenchyma or typical AML areas. In this case it is proposed that p53 mutation may play an important role in malignant transformation of renal AML.

Malignant epithelioid angiomyolipoma ('sarcoma ex angiomyolipoma') of the kidney: a case report and review of the literature

Malignant epithelioid angiomyolipoma is a recently described rare tumor of the kidney. Its existence has been questioned, however, on the basis of incomplete evidence of malignant behavior, the absence of an associated classic angiomyolipoma component, or the absence of immunoreactivity for HMB-45 in some cases. We describe a case that was HMB-45-positive and arose in association with a classic angiomyolipoma. The patient was treated with a partial nephrectomy. Three years later, she developed rapidly enlarging liver nodules. A fine-needle aspiration of the liver confirmed the presence of pleomorphic epithelioid cells morphologically and immunohistochemically identical to those comprising the primary renal tumor. After two cycles of treatment with doxorubicin, there was a 50% reduction in the size of the tumors with marked improvement in performance status. We believe this case confirms the existence of a malignant epithelioid angiomyolipoma.