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

Angiomyolipoma Originating From the Nasal Vestibule: A Case Report

Angiomyolipoma is a benign, mesenchymal, hamartomatous lesion often described in the kidney and may be associated with tuberous sclerosis. Nasal angiomyolipoma is an extremely rare tumor with fewer than 20 cases reported in the literature. We report a case of angiomyolipoma arising in the right nasal vestibule in a 68-year-old male with mild, recurrent right-sided epistaxis, and nasal obstruction. With the exception of arterial hypertension, the patient did not have any comorbidities. Gross examination showed a well-circumscribed, lobulated mass. On the microscopic level, it was composed of mature smooth muscle cells, thick-walled blood vessels of varying sizes, and islands of mature adipose tissue. Angiomyolipoma should be considered as a differential diagnosis for unilateral nasal masses, especially those situated in the nasal vestibule.

Primary renal malignant epithelioid angiomyolipoma with distant metastasis: a case report and literature review

Epithelioid angiomyolipoma (EAML) is a rare type of mesenchymal angiomyolipoma with potential malignancy in the kidney that can cause lymph node metastases, local recurrence, and distant metastases. Herein, we describe a case of EAML in the right kidney of a 51-year-old man who was admitted to the hospital with a right abdominal mass. Computed tomography revealed a heterogeneously enhanced mass with blurred margins, which was considered a malignant tumor. A radical nephrectomy was then performed. Two years later, the patient developed liver metastases from EAML and was administered sintilimab combined with bevacizumab. The patient survived after 6 months of follow-up. Histologically, the tumors showed clear boundaries and no obvious capsules. The tumor tissue mainly consisted of epithelioid tumor cells, thick-walled blood vessels, and a small amount of adipose tissue. Tumor cells with lipid vacuoles and acinar areas were large, round, polygonal, eosinophilic, or transparent in the cytoplasm. The enlarged and hyperchromatic nuclei were accompanied by distinct nucleoli and pathological mitosis. These histopathological findings resembled those of renal cell carcinoma, and immunohistochemical analysis was performed. The tumor cells were diffusely positive for HMB45, Melan-A, CK20, vimentin antibodies, and TFE3, suggesting that the tumor originated from perivascular epithelioid cells, excluding renal cell carcinoma. The Ki-67 index was 10%. These histopathological features were observed in liver mass puncture tissues. We also summarized 46 cases of EAML with distant metastasis and explored the clinicopathological features of EAML to improve the treatment of the disease. EAML is often ignored in the clinical setting, leading to metastasis and recurrence. Therefore, EAMLs require long-term follow-up, and timely detection of recurrent disease can improve the prognosis.

Clinical challenges and management of primary renal epithelioid angiomyolipoma of duplex kidney with paraneoplastic syndrome

Giant renal epithelioid angiomyolipoma of a duplex kidney has rarely been reported, especially in patients with paraneoplastic syndrome. The present report describes a 33-year-old man of Miao nationality who presented with a 6-month history of intermittent dull pain in the left upper abdomen that occurred after eating. Ultrasonography, intravenous pyelography, and computed tomography revealed a mass lesion localized in the left kidney and connected to the left renal artery. Radical nephrectomy was successfully performed, and the postoperative histopathological examination verified the lesion as epithelioid angiomyolipoma. Inpatient treatment for paraneoplastic syndrome was also performed. The present case is discussed in the context of the patient’s clinical presentation and imaging findings, drawing attention to the challenges and management of this condition to assist clinicians in practice.

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.

Everolimus in Invasive Malignant Renal Epithelioid Angiomyolipoma

Background

To evaluate the efficacy and safety of everolimus, a mTOR inhibitor, on invasive malignant renal epithelioid angiomyolipoma (EAML).

Materials and Methods

From Oct 2014 to May 2019, we collected data from seven patients with a definite (clinical and pathological) diagnosis of EAML received everolimus in our hospital. Targeted sequence capture array technique with next-generation of high throughput sequencing (NGS) were performed to detect mutations of TSC1/2 genes. All patients had received surgery and everolimus. The clinical efficacy and safety of the therapy were evaluated.

Results

Mutations of TSC1 and TSC2 were detected in two and three patients though targeted sequence capture array technique with NGS, respectively. Among seven patients, three had missense mutations, one had nonsense mutation, and one had the large fragment deletion mutation. Five patients accompanied with tuberous sclerosis complex (TSC) were identified. All patients were administered 10mg everolimus once daily, the treatment duration lasted for 3 to 28 months. The objective response was assessed 3 months later, five partial response, two stable disease (SD), the mean greatest tumor diameter of all patients decreased from 9.6 to 5.2cm. Six patients stayed SD and one patient died during follow up. Patients accompanying with TSC had better responses to everolimus compared with non-TSC.

Conclusion

The mTOR inhibitor can be an effective treatment for patients with invasive malignant renal EAML. Patients with TSC may benefit more from the therapy.

Angiomyolipoma of the kidney: from simple hamartoma to complex tumour

Angiomyolipoma is the most common mesenchymal tumour of the kidney, even if for a long time it has been viewed as a hamartoma rather than a neoplasm. It belongs to a family of neoplasms, named PEComa, characterised by the constant presence of perivascular epithelioid cells that co-express smooth muscle and melanogenesis markers. Angiomyolipoma can occur in patients with tuberous sclerosis, a hereditary syndrome due to the alteration of TSC1 or TSC2 genes, or sporadically. Angiomyolipoma and its variants are indolent tumours; however, some epithelioid angiomyolipomas/pure epithelioid PEComas are aggressive, and criteria for malignancy have been proposed to identify those cases. Although typical angiomyolipoma is a straightforward diagnosis, pathologists should be aware of the wide morphological spectrum of its variants which could be tricky in routine clinical practice and could require immunohistochemical analysis for resolution. The differential diagnosis may range from an inflammatory process (for instance xanthogranulomatous pyelonephritis) to the most common renal cancers and sarcomas. The immunoexpression of melanogenesis markers (HMB45 and Melan-A) and cathepsin K is extremely helpful in the majority of cases. Recently, a subset of epithelioid angiomyolipoma/pure epithelioid PEComa harbouring TFE3 gene fusions has been described, raising questions about its relationship with the family of perivascular epithelioid cell tumour. The activation of the mTOR pathway due to genetic alterations of tuberous sclerosis complex in TSC1 or TSC2 genes in angiomyolipoma has also been reported as well as the subsequent therapeutic implications.

Renal Epithelioid Angiomyolipoma: A Case Report and Review of Literature

Epithelioid angiomyolipoma (EAML) is an uncommon renal neoplasm with malignant potential. It is classified under the group of perivascular epithelioid cell tumors and can be sporadic or as part of the tuberous sclerosis complex. On imaging, unlike classical AML that contains fat, EAML has a very low percentage of fat which can mimic the imaging findings of renal cell carcinoma. We reported a 31-year-old female who had a history of renal failure and bilateral renal masses. Magnetic resonance imaging of the abdomen revealed bilateral large renal masses replacing renal parenchyma with features suggestive of bilateral renal AML. The patient underwent left nephrectomy, and histopathology examination findings were consistent with the diagnosis of EAML.

[Malignant epithelioid angiomyolipoma of the kidney: a rare case]

Epitheloide angiomyolipoma (EAML) is a very rare type of benign mesenchymal angiomyolipoma. In contrast to classical angiomylipoma, lymph node metastases, local recurrence and distant metastases occur in one third of patients with EAML. We report the case of a 49-year-old patient with a large recurrence of EAML of the left kidney. According to the literature, this is the first case of a malignant EAML with local recurrence in Germany.

Angiomyolipoma of the Nasal Cavity: A Distinct Entity. A Case Report and Literature Review

Angiomyolipoma (AML) is a mesenchymal tumor commonly found in the kidneys. Extra-renal AML is uncommon and especially rare in the nasal cavity. To our knowledge, fewer than five cases of nasal AML are reported in the United States. We present a case of nasal AML in a 65-year-old man with a history of rhinosinusitis and obstruction of the left nasal cavity. The lesion comprised of admixed spindled smooth muscle cells, mature adipose tissue, and thick-walled blood vessels. Smooth muscle differentiation of the spindled cells was confirmed by expression of smooth muscle actin. Surprisingly, melanocytic markers, such as HMB45, were negative. The histologic features and immunoprofile suggest that nasal AML is pathologically distinct from neoplastic AMLs/perivascular epithelioid cell tumors (PEComas) that typically occur in the kidney. We propose that nasal AML is a hamartomatous lesion rather than neoplastic. Although AML is rare in the nasal cavity, it should be considered in the differential diagnosis of clinically benign nasal masses.

Metastatic epithelioid angiomyolipoma treated with everolimus in a patient receiving hemodialysis: A case report

Introduction

A patient undergoing hemodialysis and being treated with everolimus for metastatic epithelioid angiomyolipoma has never been described in the literature, to our knowledge.

Case presentation

A 53‐year‐old woman who had undergone trans‐arterial embolization for epithelioid angiomyolipoma was referred with a chief complaint about right knee pain. Hemodialysis had been started after the embolization. Needle biopsy specimens of tumors obtained from behind the right kidney and in the right femur were diagnosed as epithelioid angiomyolipoma metastases. The patient underwent treatment with everolimus and achieved a partial response after 6 months of treatment without serious adverse events.

Conclusion

Everolimus might be effective for patients with metastatic epithelioid angiomyolipoma who are undergoing hemodialysis.

Partial nephrectomy can be a successful treatment option for renal epithelioid angiomyolipoma: a case report and literature review

Background

Renal epithelioid angiomyolipoma is a rare tumour which involves kidneys in most cases. It is known for its aggressive behaviour as a significant number of cases have been associated with metastatic epithelioid angiomyolipoma. Usually, radical treatment with systemic therapy is recommended. Only a small number of cases of epithelioid angiomyolipomas have been reported with the standard treatment being radical or partial nephrectomy. We present a  case report showing that partial nephrectomy can be a successful treatment option for renal epithelioid angiomyolipoma. This is the first case of this nature in Lithuania.

Case presentation

In this case, a 40-year-old male with epithelioid angiomyolipoma of the left kidney is presented. In 2012, a cystic left renal mass 40 × 41 mm in size was diagnosed incidentally while performing ultrasound and later confirmed by MRI. Due to the size of the tumour and the possibility of renal cell carcinoma, surgery was scheduled. Left partial nephrectomy was performed successfully. Final pathology report came back with the diagnosis of renal epithelioid angiomyolipoma. The patient had yearly follow-up for six years by CT scan, and neither recurrence nor progression were observed.

Conclusions

Early detection and diagnosis are crucial for treatment as the tumour tends to have malignancy potential. With early diagnosis, partial nephrectomy can be performed with yearly follow-up and no systemic treatment required.

Huge renal epithelioid angiomyolipoma - A case report of a giant, benign renal mass

INTRODUCTION

Renal angiomyolipoma (also called renal hamartoma) is a benign Tumor, composed of adipose tissue, smooth muscle tissue, and blood vessels. Tumors more than 10 cm (referred to as "giant" AMLs) are infrequent and a very small number of reported cases were measured more than 20 cm. Epithelioid angiomyolipoma (EAML), is a rare variant of angiomyolipoma with malignant potential. There are less than 10 cases of huge EAML reported in English literature, that were all associated with recurrence and complications.

CASE PRESENTATION

Here we report a rare case of renal EAML in a 48-year-old male patient that was not associated with tuberous sclerosis. He was admitted to our hospital with a complaint of severe abdominal pain. Computer Tomography Scan (CT-scan), revealed two masses attached to the left kidney with a size of 32 × 22 × 8 cm and 20 × 10 × 3 cm. The patient underwent a radical left nephrectomy. Postoperative histopathological examination confirmed the diagnosis of an EAML. The two-year follow-up CT-scan showed no recurrence.

CONCLUSION

Malignant EAML, although rare, does exist. Thus, besides evaluations required for ruling out the diagnosis of renal sarcomas, surgeons must follow patients after total nephrectomy for possible recurrence. Benign cases can be completely cured by surgery and do not show recurrence at the end of the follow-up period.

Intratesticular Angiolipoma: A Rare Case of Adipose Tissue Presence in the Testis

Introduction

Solid, fat-containing tumors of the testes are extremely rare with only a few cases having been reported so far, contrary to the more frequent occurrence of paratesticular lipomatosis. Testicular angiomyolipomas and gonadal involvement in Cowden's disease, although infrequently occurring, are known examples of fat-bearing testicular lesions. Hereby, we present an extremely rare case of intratesticular angiolipoma. Angiolipomas are benign tumors of the subcutaneous tissue commonly occurring in the trunk and the extremities. Histologically, they are characterized by ample vascularity and an excess of mature adipocytes. Definitive diagnosis is established by biopsy of the lesion.

Presentation of the Case

A 35-year-old patient presented to our andrology outpatient clinic for fertility assessment. Physical examination of external genitalia revealed no significant pathology. Testicular ultrasound however depicted an isoechoic lesion on the upper pole of the right testis measuring 1.8 cm × 0.8 cm × 1 cm and exhibiting intense arterial flow. After sonographic and MRI investigation, the patient was referred for semen analysis and cryopreservation. Subsequently, the patient underwent testicular biopsy (frozen section biopsy) and right partial orchiectomy. Final histology reported a noninfiltrating testicular angiolipoma. No recurrences have been observed in the follow-up period.

Discussion

Angiolipomas, which mainly occur in the trunk and extremities, are classified as infiltrating and noninfiltrating. The diagnosis is based on both clinical and histologic criteria, and the main method of treatment for both types is by surgical excision. The infiltrating type exhibits higher recurrence rates.

Conclusion

Angiolipomas commonly occur in the subcutaneous tissue and have been invariably treated by radical excision. Hereby, we report the first case of an intratesticular, noninfiltrating type angiolipoma which was treated by partial orchiectomy.

Two novel TSC2 mutations in renal epithelioid angiomyolipoma sensitive to everolimus

People who suffers renal angiomyolipoma (AML) has a low quality of life. It is widely known that genetic factors including TSC2 mutation contribute to certain populations of renal AML-bearing patients. In this study, we are the first to identify novel TSC2 mutations in one Chinese renal epithelioid AML patient: c.2652C>A; c.2688G>A based on sequencing result from biopsy tissue. These two somatic mutations cause a translational stop of TSC2, which leads to mTORC1 activation. Given the fact that activation of mTORC1 ensures cell growth and survival, we applied its inhibitor, FDA-approved everolimus, to this woman. After months of treatment with everolimus, Computer-Tomography (CT) scan results showed that everolimus successfully reduced tumor growth and distal metastasis and achieved partial response (PR) to everolimu according to Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Further Blood Routine Examination results showed the concentration of red cell mass, hemoglobin, white blood cell (WBC), platelets and hematocrit (HCT) significantly returned to normal levels indicating patients with these two TSC2 mutations could be effectively treated by everolimus.

Late local, peritoneal and systemic recurrence of renal angiomyolipoma: A case report

Renal angiomyolipoma (AML) is a relatively rare tumor that is generally considered as merely benign. However, epithelioid AML (EAML), an uncommon subtype, is associated with potentially malignant behavior. We herein present the case of a 60-year old male patient who had undergone left nephrectomy with left adrenalectomy and lymphadenectomy for a renal tumor 12 years earlier, and presented to our hospital with dull abdominal pain. The histology report after the previous surgery had revealed an AML of the left kidney with a maximal diameter of 17 cm. Imaging studies demonstrated a large tumor of 13 cm in diameter in the area of the resected kidney, as well as hepatic and peritoneal metastases. Computed tomography-guided core needle biopsy of the mass and revision of the histology of the nephrectomy revealed an EAML. Four years after a two-stage resection of the recurrences the patient is in excellent condition and free of disease. From this case report and the literature review on EAML, it appears that correct histological diagnosis of this subtype of renal AML is crucial. Erroneous diagnosis of simple renal AML instead of EAML may lead to insufficient postoperative management. Clinicians should be aware of the malignant potential of EAML and the need for long-term follow-up. As effective surgical and emerging medical treatment options are available, timely detection of recurrent disease may lead to improved outcome.

An unusual case of tuberous sclerosis incidentally discovered in adulthood: case report and review of the literature

Tuberous sclerosis (TS) is a relatively rare multi-organ disorder generally diagnosed in infancy and described as a clinical triad of sebaceous adenoma, mental retardation, and seizures. Angiomyolipoma (AML) is the most common benign renal tumor usually found incidentally as a solitary small echogenic lesion on grayscale ultrasound. Less commonly, it is part of the TS complex and is seen as multiple lesions in both kidneys. We describe an unusual case of TS incidentally diagnosed in a 37-year-old female patient with several and bilateral renal AMLs and a single cortical–subcortical tuber in the right parieto-occipital cerebral lobe.

Does epithelioid angiomyolipoma have poorer prognosis, compared with classic angiomyolipoma?

Purpose

Classic angiomyolipoma (AML) is common benign kidney tumor. However, some studies have claimed that epithelioid angiomyolipoma (EAML) has malignant potential. We compared the patient characteristics and prognosis of EAML and classic AML to demonstrate predicting factors and poorer prognosis of EAML.

Materials and Methods

The medical records of 231 patients who were diagnosed with EAML (n=27, 11.7%) or classic AML (n=204, 88.3%), were reviewed. All patients underwent computed tomography (CT) scans before operation or needle biopsy. We assessed the age, sex, tumor size, body mass index, comorbidities, and Hounsfield unit (HU) according to each CT phase. We defined the unfavorable group as patients with recurrence, metastasis and death due to tumor progression. Logistic regression analysis was used to predict EAML.

Results

EAML patients were younger (41.2 years vs. 49.1 years, p=0.001), predominantly male (55.6% vs. 28.4%, p=0.005), and had a larger tumor (7.5 cm vs. 4.2 cm, p<0.001). The median pre-contrast HU was not significantly different between EAML and classic AML (29.9±23.7 vs. 14.7±41.0, p=0.071). In multivariable analysis, younger age (odds ratio [OR], 0.96; p=0.032), male sex (OR, 3.33; p=0.013), and tumor larger than 4 cm (OR, 3.8; p=0.009) were significant predictive factors. Five patients (18.5%) had unfavorable outcomes, two patients had lymph node metastasis, and three patients had lung metastasis.

Conclusions

Patient and tumor characteristics can be helpful in determining the type of AML preoperatively. Younger age, male sex, and larger tumor mass may increase the possibility of diagnosing EAML. EAML has malignant potential and requires careful follow-up.

Durable response to anti-PD-1 immunotherapy in epithelioid angiomyolipoma: a report on the successful treatment of a rare malignancy

BACKGROUND

Malignant angiomyolipoma is an uncommon tumor of the class of perivasciular epithelioid cell neoplasms (PEComas). These tumors are characteristically driven by deleterious mutations in the tumor suppressors TSC1 and TSC2, whose gene products typically act to inhibit mTOR. There are several cases of malignant angiomyolipoma which exhibit transient responses to mTOR inhibitors, forming the basis of current practice guidelines in malignant PEComa. However the tumors ultimately acquire resistance, and there is no well-established second-line option. Despite the increasing prevalence of immunotherapy across a wide range of solid tumors, little is known about the immune infiltrate and PD-L1 expression of angiomyolipoma. Furthermore, there is no reported case on the treatment of malignant angiomyolipoma with an immune checkpoint inhibitor.

CASE PRESENTATION

A 38 year-old man presented with gross hematuria and was diagnosed with renal epithelioid angiomyolipoma. Despite surgical resection, the tumor recurred and metastasized. Targeted genomic sequencing revealed a deleterious mutation in TSC2, and the patient was treated with the mTOR inihbitor everolimus. The patient went on to have a partial response but ultimately progressed. He was then treated with the anti-PD-1 immune checkpoint inhibitor nivolumab, and achieved a durable near-complete response which is ongoing after two years of treatment. Immunohistochemical staining of tumor tissue revealed strong PD-L1 expression and a brisk T-cell infiltrate.

CONCLUSIONS

We report on the first durable systemic treatment of malignant epithelioid angiomyolipoima with the use of PD-1 antibody nivolumab. Given the absence of prospective clinical trials in this exceedingly rare disease, particularly in the second-line setting, immune checkpoint inhibitors like nivolumab should be considered.

Primary kidney malignant epithelioid angiomyolipoma: Two cases report and review of literature

RATIONALE

Epithelioid angiomyolipoma (EAML) is a subtype of angiomyolipoma with malignant potential. A diagnosis of malignant EAML of the kidney is based on extrarenal metastasis, and predicting early transformation is difficult. To propose criteria for indicators of malignant transformation, herein we report 2 cases and review 17 cases reported in the literature (2000-2017).

PATIENT CONCERNS

Tumor of the kidney was determined in 2 patients, and tissues after nephrectomy were pathologically, histologically, and immunochemically examined.

DIAGNOSIS

Malignant EAML.

INTERVENTION

The 2 present patients were treated with nephrectomy only.

OUTCOMES

Case 1 involved a 48-year-old woman with a 7.5-cm solid mass in the right kidney who underwent nephrectomy. CT detected a mass in the liver after 13 months, which was speculated to be metastasis from the kidney lesion. Case 2 involved a 62-year-old man with a 7-cm cystic solid mass in the left kidney who accepted nephrectomy and at 10 months post-surgery lived with no disease. Both cases presented a large tumor, atypical epithelioid cells, mitotic figures, and necrosis; tested positive for melanocytic markers (HMB45, MelanA).

LESSONS

The literature review of malignant EAML led to the identification of 8 malignant features: size ≥5 cm; metastasis; infiltration; necrosis; ≥50% atypical epithelioid cells; cytologic atypia; atypical mitosis; and vessel invasion. The co-existence of at least 5 of these is proposed to indicate malignant EAML. Features of our 2 new cases of primary malignant EAML of the kidney matched these criteria. Our proposal of criteria for predicting malignant feature, based on 2 new cases and 17 cases in the literature, should aid understanding and avoid misdiagnosis. Nephrectomy is currently the common treatment strategy for malignant EAML, but more effective treatment strategies are needed to provide a better prognosis for patients.

Malignant renal epithelioid angiomyolipoma with TFE3 gene amplification mimicking renal carcinoma

Malignant renal epithelioid angiomyolipoma (EAML) is an extremely rare disease with a poor prognosis, and currently there are no uniform criteria for its biological behavior. Here, we present a case of malignant renal EAML with TFE3 gene amplification in a 53-year-old woman. Four months after surgery, unenhanced computed tomography scans showed recurrence as well as metastasis in the abdomen and lung. The patient succumbed to rapid neoplastic progression of the disease 6 months later.

Case Report of a Hepatic Angiomyolipoma

Angiomyolipoma (AML) is a benign mesenchymal tumor that has been frequently reported in the kidney but rarely in the liver. Hepatic AML may be clinically, radiologically and morphologically difficult to distinguish from hepatocellular carcinoma or other hepatic lesions, even though the number of cases has been increasing recently due to improved imaging techniques. Histologically it consists of smooth muscle cells, adipose cells and abnormal blood vessels. It is commonly diagnosed following abdominal pain but may also be asymptomatic, has a predominant female predilection, highly variable size and occurs in subjects with a wide age range. The right lobe is the most common site, and multicentricity has been reported. Here we report a case of the myomatous variant of AML, accidentally discovered in a young woman with no clear features on radiographic examination, which was diagnosed by means of fine needle aspiration biopsy (FNAB) and then surgically removed. Although careful observation with serial radiological follow-up is an option in these cases, we chose the surgical approach because of the risk of rupture due to the large size of the lesion and the risk of malignant behavior or transformation. In case of the myomatous variant composed of irregular cells with epithelioid appearance, hepatocellular carcinoma with fatty changes or the possibility of other malignant tumors must be ruled out by immunohistochemistry (HMB-45), even in biopsy specimens.

Peroxisome proliferator-activated receptor gamma (PPARγ) is central to the initiation and propagation of human angiomyolipoma, suggesting its potential as a therapeutic target

Angiomyolipoma (AML), the most common benign renal tumor, can result in severe morbidity from hemorrhage and renal failure. While mTORC1 activation is involved in its growth, mTORC1 inhibitors fail to eradicate AML, highlighting the need for new therapies. Moreover, the identity of the AML cell of origin is obscure. AML research, however, is hampered by the lack of in vivo models. Here, we establish a human AML‐xenograft (Xn) model in mice, recapitulating AML at the histological and molecular levels. Microarray analysis demonstrated tumor growth in vivo to involve robust PPARG‐pathway activation. Similarly, immunostaining revealed strong PPARG expression in human AML specimens. Accordingly, we demonstrate that while PPARG agonism accelerates AML growth, PPARG antagonism is inhibitory, strongly suppressing AML proliferation and tumor‐initiating capacity, via a TGFB‐mediated inhibition of PDGFB and CTGF. Finally, we show striking similarity between AML cell lines and mesenchymal stem cells (MSCs) in terms of antigen and gene expression and differentiation potential. Altogether, we establish the first in vivo human AML model, which provides evidence that AML may originate in a PPARG‐activated renal MSC lineage that is skewed toward adipocytes and smooth muscle and away from osteoblasts, and uncover PPARG as a regulator of AML growth, which could serve as an attractive therapeutic target.

[Epithelioid angiomyolipoma of the kidney: About one case and malignant features evaluation]

Renal epithelioid angiomyolipoma (E-AML) is a rare mesenchymal tumor of the kidney included in the family of tumor with perivascular epithelioid cell differentiation (PEComas) and is frequently associated with tuberous sclerosis complex. Since its clinical and radiological features are not specific, the diagnosis remained mostly pathological. Microscopically, E-AML demonstrate proliferation of more than 80% of epithelioid cells with atypia, often associated with necrosis, hemorrhage, mitotic activity and vascular invasion. Tumor's cells are immunohistochemically positive for melanocytic and smooth muscle markers. The pathologic prognostic predictors are not well known and the malignancy remained based on the identification of distant metastasis. We herein report a case of E-AML diagnosed in a 58-year-old woman and review analysis in the literature to discuss the prognostic indicators of malignancy useful for risk stratification of E-AML and to manage the patients.

Malignant renal epithelioid angiomyolipoma: A case report and review of the literature

Malignant renal epithelioid angiomyolipoma (EAML) is rare, and currently there is no malignant criteria for its pathological diagnosis. In the present study, the case of a patient who suffered malignant renal EAML and underwent nephrectomy is reported. The histological patterns of the tumor were composed of sheets or nests of large polygonal epithelioid cells and thick-walled blood vessels, with clear mitoses. Immunohistochemistry demonstrated that the epithelioid and smooth muscle cells characteristically expressed human melanoma black-45, epithelial membrane antigen and actin. Pathological evaluation revealed malignant EAML with regional lymph node metastases. Magnetic resonance imaging and X-ray examination identified multiple liver and lung nodules at 16 months post-surgery. Since the patient did not respond to the initial treatment with doxorubicin and cisplatin, sorafenib was subsequently administered. However, the treatment was not effective, and the patient succumbed to multiple metastases six months later.

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 being surgically excised for presumed kidney carcinoma

OBJECTIVE

To explore the important factors involved in angiomyolipoma (AML) being preoperatively misclassified and surgically removed for presumed kidney carcinoma.

MATERIALS AND METHODS

From 2008 to 2014, AML was pathologically confirmed in 38 patients who underwent radical or partial nephrectomy for presumed malignant renal tumor. Control group 1 were patients with renal cell carcinoma (RCC) matched for age and tumor size; control group 2 were patients with typical AML matched for age and sex. Pertinent data of the studied group and its matched control groups were recorded and analyzed.

RESULTS

The mean age of the patients in study group was 48.11 ± 12.92 years, and the mean tumor size was 3.12 ± 1.68 cm (range 0.9-9.4). More than 84 % of the misclassified AMLs measured ≤4 cm, and over 21 % patients underwent radical nephrectomy. The only statistically significant feature between the misdiagnosed AML group and the matched RCC group is mean age (48.11 ± 12.92 vs. 56.92 ± 10.28, P = 0.002). Compared with the matched typical AML group, the misdiagnosed AML group has smaller mean tumor size (3.12 ± 1.68 vs. 5.85 ± 3.33, P < 0.001), but more patients undergoing radical nephrectomy (21.05 vs. 0 %, P = 0.003). Two main imaging features, which are hypoechoic on ultrasonography and fat density on computed tomography (CT), were statistically different between the two groups. The misdiagnosis of AML was significantly associated with no fat density on CT (OR 5.528, P = 0.004) and hypoechoic on ultrasonography (OR 3.845, P = 0.017).

CONCLUSIONS

A number of AMLs were misdiagnosed as RCCs, causing a large number of unnecessary surgeries. No fat density on CT and no hyperechoic on ultrasonography resulting from small tumor size were the two most important factors causing AML being excised for presumed kidney carcinoma. Ultrasonography and CT cannot differentiate atypical AML from kidney carcinoma effectively, so improved renal biopsy and noninvasive biomarkers are urgently warranted to prevent us from excising benign renal tumor aggressively.

A Four-Year Follow-up Study of Renal Epithelioid Angiomyolipoma: A Multi-Center Experience and Literature Review

In this study, we systematically explored the clinical manifestations, diagnosis, treatment, and prognosis of renal epithelioid angiomyolipoma (EAML) retrospectively by analyzing data of 52 patients diagnosed with EAML at four centers. Our results showed that the onset of EAML was usually inconspicuous, and so no obvious symptoms or signs had occurred in most patients at diagnosis. Its diagnoses always depended on postoperative pathological examination. The immunohistochemical (IHC) results [HMB45 ( + ), cytokeratin (-), and S100 (-)] could be used to differentiate EAML from other malignancies such as renal cell cancer (RCC) and sarcomas. For treatment, surgery resulted in satisfactory short-term prognosis. The long-term prognosis of patients with EAML was poor, particularly when a large size, a high percentage of epithelioid component, tumor thrombus formation, and necrosis were present. In conclusion, EAML is a tumor with malignant potential. Once diagnosed, integrated approaches, including surgery, chemotherapy, and targeted therapy, should be considered; a close follow-up regimen is necessary for cases that met: 1) tumor size >9 cm, 2) tumor thrombus formation in the vein, 3) epithelioid cells >70% or atypia cells >60%, and 4) necrosis.

Renal epithelioid angiomyolipoma with malignant features: Histological evaluation and novel immunohistochemical findings

Renal epithelioid angiomyolipoma (EAML) is a potentially malignant tumor type whose characteristics and biomarkers predictive of malignant behavior have not been elucidated. Here, we report three cases of renal EAML with malignant features but without histories of tuberous sclerosis complex. Case 1 involved a 29-year-old man with a 12-cm solid mass in the right kidney who underwent radical right nephrectomy. Case 2 involved a 22-year-old woman with a retroperitoneal mass who underwent radical right nephrectomy and retroperitoneal tumorectomy. Local recurrence was detected 7 years post-surgery. Case 3 involved a 23-year-old man with a 14-cm solid mass in the left kidney who underwent radical left nephrectomy. Microscopically, the tumors in all cases demonstrated proliferation of epithelioid cells with atypia, mitotic activity, necrosis, hemorrhage, and vascular invasion. Epithelioid cells in all cases were immunohistochemically positive for melanocytic and myoid markers and weakly positive for E-cadherin and β-catenin. Immunohistochemistry revealed activation of the mammalian target of rapamycin pathway. Here, we report the morphological and immunohistochemical features of clinically or histologically malignant renal EAML.

The analysis of mutations and exon deletions at TSC2 gene in angiomyolipomas associated with tuberous sclerosis complex

Angiomyolipomas (AMLs) are relatively rare hamartomatous or benign tumors that occasionally occur as part of tuberous sclerosis complex (TSC). Mutations in either of the two genes, TSC1 and TSC2, have been attributed to the development of TSC. Between 1994 and January 2009, 83 patients were diagnosed with AML at the Samsung Medical Center. In that group of patients, 5 (6%) had AML with TSC (AML-TSC). Mutational analysis of the TSC2 gene was performed using 7 samples from the 5 AML-TSC patients and 14 samples from 14 patients with sporadic AML without TSC (AML-non-TSC). From this analysis, mutations in TSC genes were identified in 5 samples from the AML-TSC patients (mutation detection rate=71%) and 3 samples from AML-non-TSC patients (mutation detection rate=21%). In the case of AML-TSC, 6 mutations were found including 3 recurrent mutations and 3 novel mutations, while in the case of AML-non-TSC, 4 mutations were identified once, including 1 novel mutation. Also MLPA analysis of the TSC2 gene showed that TSC2 exon deletion is more frequently observed in AML-TSC patients than in AML-non-TSC patients. This is the first mutation and multiplex ligation-dependent probe amplification (MLPA) analyses of TSC2 in Korean AMLs that focus on TSC. This study provides data that are representative of the distribution of mutations and exon deletions at TSC genes in clinically diagnosed AML-TSC cases of the Korean population.

Comprehensive clinical and pathological analysis of aggressive renal epithelioid angiomyolipoma: report of three cases

Renal angiomyolipoma (AML) is recognized as a benign hamartomatous lesion arising in the kidney with no obvious malignant potential. However, epithelioid AML (EAML), a rare variant of AML, is potentially malignant, with aggressive clinical features. It can occur in patients with or without tuberous sclerosis. Because EAML may mimic renal cell carcinoma in imaging studies, differentiation of this tumor from renal cell carcinoma preoperatively is difficult. At times, the lesions may extend into the renal vein and inferior vena cava or metastasize to other organs such as the lung and liver. To clarify the biological nature of EAML, three specific cases that we encountered in clinical practice are analyzed and reported in detail.

Epithelioid angiomyolipoma of the kidney: pathological features and clinical outcome in a series of consecutively resected tumors

The 2004 World Health Organization classification of tumors defines epithelioid angiomyolipoma of kidney as a potentially malignant mesenchymal neoplasm with reported metastasis in approximately one-third of the cases. However, this conclusion was based primarily on individual case reports and small retrospective series. More recently reported larger series have shown varying results. We reviewed 437 consecutive renal angiomyolipomas with primary resection at three tertiary-care institutions with high nephrectomy volumes. Only tumors showing >80% epithelioid histology were included in this study. Tumors resected elsewhere and reviewed in consultation were not included. Twenty of these 437 (4.6%) were classified as epithelioid angiomyolipoma. The female to male ratio was 11:9, mean age 49.7 (range, 30-80) years, and mean tumor size 8.7 (range, 1-25) cm. Microscopic tumor necrosis was present in 10 (50%) tumors and mitotic activity (range, <1-5/10 high power fields) in 8 (40%); atypical mitoses were seen in only 1 (5%) tumor. Pleomorphic ganglion-like or multinucleated giant cells were seen in 18 (90%) tumors. With a mean follow-up of 82.5 (range, 1-356) months, seventeen patients were alive with no-evidence-of-disease at the time of last follow-up; two patients died of unrelated causes with no-evidence-of-disease, and one patient (5%) developed distant metastases. Our data, based on consecutively resected angiomyolipomas with long clinical follow-up, suggests that epithelioid angiomyolipomas constitute a small proportion of all angiomyolipomas, and the rate of aggressive behavior among epithelioid angiomyolipomas, even when showing morphologic features previously reported to portend aggressive clinical behavior, is very low.

Fatal malignant metastastic epithelioid angiomyolipoma presenting in a young woman: case report and review of the literature

Epithelioid angiomyolipomas (EAMLs) are rare mesenchymal tumors whose malignant variant is extremely uncommon and highly aggressive. Treatment strategies include chemo radiation, transcatheter arterial embolization and surgical resection, which has remained the mainstay treatment. Targeted therapies including mammalian target of rapamycin (mTOR) inhibitors such as Temsirolimus may offer some hope for progressive malignant EAMLs that are not amenable to other treatment modalities. We report a fatal case in a young female who presented with rapidly progressive metastatic EAML that did not respond to mTOR therapy. The literature has shown reduction in tumor burden with the use of mTOR inhibitors, but unfortunately due to the rarity of malignant EAML, a meaningful approach to treatment remains challenging.

A 22-year-old female with invasive epithelioid angiomyolipoma and tumor thrombus into the inferior vena cava: case report and literature review

A 22-year-old female presented with back pain and was discovered to have a right-sided abdominal mass. Computed tomography (CT) scan revealed a 9 cm enhancing right upper pole renal mass with suspicion for tumor thrombus into the right renal vein and possibly the inferior vena cava (IVC). Magnetic resonance imaging (MRI) confirmed tumor thrombus into the inferior vena cava approximately 3 cm below the hepatic venous confluence. Open right radical nephrectomy with inferior vena cava thrombectomy was performed with removal of right kidney and tumor thrombus en bloc. Pathology revealed malignant epithelioid angiomyolipoma (EAML or PEComa). Epithelioid angiomyolipoma is a rare tumor of mesenchymal tissue that has the potential for local invasion and disease progression. Diagnosis of EAML was confirmed by pathology and immunohistochemistry. She was referred to medical oncology for discussion of surveillance versus potential adjuvant therapy and ultimately opted for close surveillance.

Multiple perivascular epithelioid cell tumors: clear cell tumor of the lung accompanied by angiomyolipoma of the liver

Clear cell tumor (CCT) of the lung is very rare, and angiomyolipoma (AML) of the liver is also very rare. Both CCT and AML have been identified as a group of neoplasms with perivascular epithelioid cell differentiation (PEComa). We report a case with multiple PEComas of a combination of CCT of the lung and AML of the liver. The patient underwent surgical resection of an abnormal nodule of the lung 5 years after treatment of AML of the liver. The histological diagnosis of the pulmonary nodule was CCT. Neither lesion demonstrated malignant phenotypes, such as high mitotic activity, necrosis, or lymphovascular invasion. Each tumor of the lung and liver was solitary and differed from each other histologically. Therefore, these tumors were considered to be multifocal, not metastatic PEComas. This case is, to our knowledge, the first report of multiple PEComas of pulmonary CCT and hepatic AML. These findings suggest that patients with PEComas may require whole-body follow-up examinations because different subtypes of PEComas may occur multifocally.

Role of mammalian target of rapamycin inhibitor in the treatment of metastatic epithelioid angiomyolipoma: a case report

Epithelioid angiomyolipoma has malignant potential; however, no effective therapy has been established for advanced cases. A 50-year-old woman with a history of right nephrectomy for epithelioid angiomyolipoma was referred to our institution. Computed tomography and magnetic resonance imaging showed multiple tumors in her lung, liver and pelvic cavity. The liver and pelvic tumor specimens obtained by needle biopsy confirmed the diagnosis of epithelioid angiomyolipoma recurrence. The patient was treated with everolimus (10 mg/day). Three months later, pulmonary lesions disappeared; liver and pelvic tumors significantly shrank in size, but the pelvic tumor gradually enlarged again. We carried out surgical resection of the residual liver and pelvic cavity tumors. Although the mammalian target of rapamycin inhibitor seems to be effective for treating epithelioid angiomyolipoma, its long-term effects remain unknown. Thus, aggressive administration of a multidisciplinary treatment including molecular target therapy and surgical resection is required to improve the prognosis of epithelioid angiomyolipoma.

A proposal for creating a guideline for cancer registration of the fibromatosis, PEComa group, malignant lymphoma In Situ and dendritic cell tumors (III)

BACKGROUND

Understanding the biologic behavior of a tumor is a prerequisite for tumor registration code assignment. The aim of this report was to propose appropriate behavior codes of the International Classification of Disease Oncology 3 (ICD-O3) to rare, yet pathologically interesting hematopoietic and soft tissue tumors.

METHODS

The Study Group for Hematopathology, the Bone and Soft Tissue Pathology Study Group, and the Cancer Registration Committee prepared the questionnaire containing provisional behavior codes of selected diseases.

RESULTS

In situ lesions of mantle cell and follicular lymphomas, dendritic cell tumors, and neoplasms with perivascular epithelioid cell differentiation (PEComa), not otherwise specified were classified as malignant (-/3). The fibromatosis group, with the exception of lipofibromatosis, was proposed as benign (-/0). Lipofibromatosis and several diseases that belong to the PEComa group were proposed as uncertain malignant potential (-/1). For the hematologic and soft tissue tumors, 274 and 288 members of the Korean Society of Pathologists, respectively, provided opinions through questionnaire, and most responders showed agreement with the provisional behavior code proposed.

CONCLUSIONS

The determination of behavior codes for the rare diseases described in this study, especially those of the PEComa group or malignant lymphoma, could be viewed as impractical and premature, but this study provides the basis for future research on this topic.

Child abuse in medical setting presenting as gross hematuria: diagnosis by DNA short tandem repeats

Two sisters, aged 15 and 13 years, had previous epithelioid angiomyolipoma of the kidney and suspected thin basement membrane disease, respectively. They presented with 2 years of gross hematuria and new-onset heavy proteinuria. Extensive investigations failed to find an overt cause of their urinary manifestations. The diagnosis of child abuse in a medical setting was confirmed by DNA short tandem repeats analysis, which are the first documented cases in which factitious hematuria was thus diagnosed. Complex forms of child abuse in a medical setting may require forensic tests such as DNA short tandem repeats analysis for diagnosis.

[Guidelines for the management of tuberous sclerosis complex renal disease]

PURPOSE

To review existing literature and deduce guidelines for the management of renal disease in patients with tuberous sclerosis complex (TSC).

PATIENTS

After review of literature, a core panel of five physicians wrote a draft that was evaluated by 14 reviewers who used a 9-level scale (1: total disagreement; 9: total agreement). The guidelines were then reformulated until each item received a median score superior or equal to 8.

RESULTS

Forty-eight to 80 % of TSC patients have significant renal involvement including angiomyolipomas (AMLs), cysts, malignant tumors and renal insufficiency. It is recommended to perform an abdominal ultrasound (and serum creatinine if abnormal ultrasound) when TSC is diagnosed. This work-up will be repeated every 3-5years if normal. Associated autosomal dominant polycystic kidney disease must be suspected in case of numerous and large cysts. After the age of 20, follow-up should use computed tomography (CT) or MRI that are more precise than ultrasound for the measurement of AMLs. Biopsy of a renal mass should be discussed in case of calcifications, necrosis or rapid growth. Females with TSC should undergo screening for pulmonary lymphangioleiomyomatosis by CT at the age of 18, and, if negative at the age of 30-40. Acute bleeding should be treated with percutaneous embolization. Asymptomatic angiomyolipomas with several risk factors (size>80mm, predominant vascular component, micro-aneurysms) should undergo prophylactic treatment, if possible using embolization. The role of mTOR inhibitors in the management of angiomyolipomas needs to be defined.

CONCLUSION

Standardization of follow-up and treatment is necessary to improve the management of TSC renal involvement.

Cathepsin K expression in the spectrum of perivascular epithelioid cell (PEC) lesions of the kidney

The perivascular epithelioid cell (PEC) is a unique cell type coexpressing contractile proteins (mainly α-smooth muscle actin), melanocytic markers, including microphthalmia-associated transcription factor (MITF), and estrogen and progesterone receptors. It is constantly present in a group of tumors called PEComas. Renal PEComas include the common angiomyolipoma as well as less common lesions such as microscopic angiomyolipoma, intraglomerular lesions, angiomyolipoma with epithelial cysts, epithelioid angiomyolipoma, oncocytoma-like angiomyolipoma and lymphangioleiomyomatosis of the renal sinus. It has been demonstrated that most of these lesions are determined by mutations affecting genes of the tuberous sclerosis complex, tuberous sclerosis 1 (TSC1) and tuberous sclerosis 2 (TSC2), with eventual deregulation of the RHEB/MTOR/RPS6KB2 pathway, and it has been observed that some PEComas regressed during sirolimus therapy, an MTOR inhibitor. Recently, overexpression of MITF has been related to the expression of the papain-like cysteine protease cathepsin K in osteoclasts where it has inhibited MTOR. The aim of this study is to evaluate cathepsin K immunohistochemically in the entire spectrum of PEComa lesions in the kidney. The study population consisted of 84 renal PEComa lesions, including 5 composed predominantly of fat (lipoma-like angiomyolipoma), 15 almost exclusively composed of spindle-shaped smooth muscle cells (leiomyoma-like angiomyolipoma) and 31 common angiomyolipomas composed of a mixture of fat, spindle and epithelioid smooth muscle cells, and abnormal thick-walled blood vessels, 15 microscopic angiomyolipomas, 5 intraglomerular lesions, 2 oncocytoma-like angiomyolipomas, 8 epithelioid angiomyolipomas, 2 angiomyolipomas with epithelial cysts and 1 example of lymphangioleiomyomatosis of the renal sinus. In all of the renal PEComas, cathepsin K was found to be constantly and strongly expressed and seems to be a more powerful marker than other commonly used markers for their identification, especially to confirm the diagnosis on needle biopsies.

A massive renal epithelioid angiomyolipoma with multiple metastatic lymph nodes

A 47-year-old man presented with dull pain in the left upper abdomen for 1 year. Computed tomograph (CT) examination revealed a very large heterogeneously enhancing mass in the left kidney, measuring up to 28 cm. The mass was accompanied by several enlarged lymph nodes in the peri-aortic region. Radical nephrectomy was performed and pathologic evaluation revealed sheets of epithelioid cells and piecemeal necrosis consistent with malignant epithelioid angiomyolipoma (EAML) with regional lymph node metastases. The tumor cells were strongly positive for human melanosome-associated protein (HMB-45) on immunohistochemical staining. There was neither metastasis nor recurrence 2 years postoperatively. EAML is a rare tumor of mesenchymal tissue with potential for aggressive behavior. If this neoplasm is suspected based on CT features, EAML should be confirmed by pathology and immunohistochemistry.