[Hepatic epithelioid angiomyolipoma/PEComa and focal nodular hyperplasia in a patient with a previous history of cutaneous melanoma]. / Angiomiolipoma epitelioide/PEComa hepático e hiperplasia nodular focal en una paciente con antecedentes de melanoma cutáneo.

Hepatic perivascular epithelioid cell tumors (PEComas) are uncommon mesenchymal neoplasms. PEComas concurrent with other hepatic lesions is a very rare occurrence, with only two previously reported cases. We report a primary hepatic PEComa associated with focal nodular hyperplasia in a patient with a previous history of cutaneous melanoma. Diagnostic imaging studies suggested a hepatic adenoma and the patient underwent a segmentectomy. The tumor was mainly composed of epithelioid cells, adipose tissue and smooth muscle fibers intermixed with blood vessels. The neoplastic cells were diffusely immunoreactive for HMB-45, Melan-A and smooth muscle actin, but not for Hepatocyte, S100, MITF or BRAF. Molecular studies were negative for BRAFV600 mutation. The final diagnosis was hepatic epithelioid angiomyolipoma/PEComa. The differential diagnosis of hepatic PEComa is discussed.

t(6;11) renal cell carcinoma: a study of seven cases including two with aggressive behavior, and utility of CD68 (PG-M1) in the differential diagnosis with pure epithelioid PEComa/epithelioid angiomyolipoma.

Renal cell carcinomas with t(6;11) chromosome translocation involving the TFEB gene are indolent neoplasms which often occur in young patients. In this study, we report seven cases of renal cell carcinoma with TFEB rearrangement, two of whom had histologically proven metastasis. Patients (4F, 3M) ranged in age from 19 to 55 years (mean 37). One patient developed paratracheal and pleural metastases 24 months after surgery and died of disease after 46 months; another one recurred with neoplastic nodules in the perinephric fat and pelvic soft tissue. Histologically, either cytological or architectural appearance was peculiar in each case whereas one tumor displayed the typical biphasic morphology. By immunohistochemistry, all tumors labelled for cathepsin K, Melan-A and CD68 (KP1 clone). HMB45 and PAX8 staining were detected in six of seven tumors. All tumors were negative for CD68 (PG-M1 clone), CKAE1-AE3, CK7, CAIX, and AMACR. Seven pure epithelioid PEComa/epithelioid angiomyolipomas, used as control, were positive for cathepsin K, melanocytic markers, and CD68 (PG-M1 and KP1) and negative for PAX8. Fluorescence in situ hybridization results showed the presence of TFEB gene translocation in all t(6;11) renal cell carcinomas with a high frequency of split TFEB fluorescent signals (mean 74%). In the primary and metastatic samples of the two aggressive tumors, increased gene copy number was observed (3-5 fluorescent signals per neoplastic nuclei) with a concomitant increased number of CEP6. Review of the literature revealed older age and larger tumor size as correlating with aggressive behavior in these neoplasms. In conclusion, we present the clinical, morphological and molecular features of seven t(6;11) renal cell carcinomas, two with histologically demonstrated metastasis. We report the high frequency of split signals by FISH in tumors with t(6;11) chromosomal rearrangement and the occurrence of TFEB gene copy number gains in the aggressive cases, analyzing either the primary or metastatic tumor. Finally, we demonstrate the usefulness of CD68 (PG-M1) immunohistochemical staining in distinguishing t(6;11) renal cell carcinoma from pure epithelioid PEComa/epithelioid angiomyolipoma.

The Histopathological Features and CT/MRI Imaging Performances in Hepatic Angiomyolipoma Patients.

AIM: To evaluate the diagnostic value of dynamic contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) in the differential diagnosis of hepatic angiomyolipoma (HAML) and hepatocellular carcinoma (HCC) and to clarify the relationship between histopathological features and CT or MRI imaging performances in HAML. MATERIAL AND METHODS: Six HAML and 33 non-cirrhotic HCC patients confirmed by histopathology were retrospectively analyzed. The serum biomarkers, CT and MRI examinations were conventionally performed before the confirmatory histological diagnosis. The clinical data from their medical records was also analyzed. RESULTS: Six HAML patients were annotated as two types according to CT and MRI imaging characteristics, including hypovascular type (n = 1) and hypervascular type (n = 5). The imaging performances of the 33 HCC patients were hypervascular type. Moreover, all the 5 hypervascular type HAML patients were misdiagnosed as HCC by CT or MRI. We also found that the hypervascular type of HAML patients contained more vessels and less fatty tissues in histopathology than hypovascular type of HAML patients. However, the clinical features included HCC high risk factors (hepatitis B or C), non-specific symptoms, male and increased serum alpha fetoprotein (AFP) were more common in HCC patients than HAML patients (P < 0.05, respectively). CONCLUSIONS: The CT or MRI imaging performances of HAML patients containing more vessels and less fatty tissues in histopathology resemble the imaging performance of HCC patients. These clinical features may be of great help in the differential diagnosis in the current clinical practices.

A subset of fat-predominant angiomyolipomas label for MDM2: a potential diagnostic pitfall.

Angiomyolipomas (AMLs) are typically benign mesenchymal tumors with variable histologic composition. Fat-predominant AMLs can mimic well-differentiated liposarcomas (WDLSs) both radiographically and histologically because of the abundance of fat with admixed atypical cells resembling lipoblasts. However, the treatment and prognosis of AMLs and WDLSs are vastly different. Immunohistochemistry for murine double minute 2 (MDM2) has been used to support a diagnosis of WDLS; however, MDM2 labeling has not been specifically evaluated in fat-predominant AMLs. Here, we evaluated MDM2 immunohistochemistry in 36 AMLs (including 14 conventional AMLs, 13 fat-predominant AMLs, 6 fat-rich AMLs, 3 epithelioid AMLs) and 10 WDLSs. In addition, we labeled cases for HMB45, calponin, or actin, which are immunostains traditionally used to label AML. We performed fluorescence in situ hybridization (FISH) for MDM2 amplification on selected cases. By immunohistochemistry, 14% (5/36) of AMLs were MDM2+, including 23% (3/13) of fat-predominant AMLs. All MDM2+ AMLs evaluated by FISH (n=4) were negative for MDM2 amplification. By immunohistochemistry, 90% of WDLSs were MDM2+, and both MDM2+ WDLSs evaluated by FISH (n=2) were MDM2 amplified. All 36 AMLs labeled with HMB45 and calponin or actin. No WDLS labeled with HMB45; however, 80% of WDLSs labeled with calponin or actin. Although uncommon, MDM2 labeling is seen in a subset of fat-predominant AMLs and is a potential diagnostic pitfall in the evaluation of fatty tumors of the retroperitoneum. HMB45 is more sensitive and specific for AML than calponin or actin, and an immunopanel containing both HMB45 and MDM2 may be warranted to distinguish between fat-predominant AML and WDLS in histologically ambiguous cases.

Liver transplantation for recurrent posthepatectomy malignant hepatic angiomyolipoma: a case report.

Hepatic angiomyolipomas (AMLs) are typically benign tumors containing varying amounts of smooth muscle cells, adipose tissue, and vessels, and are commonly found in the kidney and occasionally in the liver. The preoperative diagnosis of hepatic AML is primarily made from imaging and fine-needle aspiration biopsy results, though limited experience for such diagnoses can result in misdiagnosis. Some uncommon features of hepatic AML have been reported in the literature without an objective or qualitative consensus. As the majority of cases are benign, conservative treatment of AMLs is recommended. However, in rare cases, liver transplantation has been implemented. Only five cases of malignant hepatic AML have been reported. We report a rare case of recurrent posthepatectomy malignant hepatic AML that was misdiagnosed as liver cancer in a 37-year-old woman, which was treated by liver transplantation. The imaging and pathologic findings are presented in order to provide a more concise description to aid in future diagnoses.

Hepatocellular carcinoma with concomitant hepatic angiomyolipoma and cavernous hemangioma in one patient.

The risk of developing hepatocellular carcinoma (HCC) is strongly associated with hepatitis B virus infection. Hepatic angiomyolipoma (AML), a rare benign tumor, is composed of a heterogeneous mixture of adipose cells, smooth muscle cells and blood vessels. Here, we report the case of a 44-year-old man who developed HCC with a concomitant hepatic AML and a cavernous hemangioma, in the absence of cirrhosis. To our knowledge, based on an extensive literature search using the www.pubmed.gov website, this is the first report of an HCC case with both concomitant AML and cavernous hemangioma at the same position in the liver. The presence of the hepatitis B surface antigen was detected, but the liver function was normal. Clinical and pathological data were collected before and during the treatment. Hepatic AML was diagnosed based on the typical histological characteristics and immunohistochemical staining, which revealed, a positive staining with a melanocytic cell-specific monoclonal antibody. There was no evidence of tuberous sclerosis complex in this patient. Although the HCC was poor- to moderately-differentiated, the characteristics of the AML and the cavernous hemangioma in this patient did not match any criteria for malignancy. Hepatectomy followed by transarterial chemoembolization treatment were effective therapeutic methods for the adjacent lesions in this patient. This case is an interesting coincidence.

Differentiation of lipid poor angiomyolipoma from hepatocellular carcinoma on gadoxetic acid-enhanced liver MR imaging.

PURPOSE: To investigate magnetic resonance (MR) findings of angiomyolipoma (AML) on gadoxetic acid-enhanced MR imaging, and to identify features that differentiate AML from hepatocellular carcinoma (HCC) in patients with a low risk of HCC development. METHODS: This retrospective study was institutional review board approved, and the requirement for informed consent was waived. Twelve patients with hepatic AML who underwent gadoxetic acid-enhanced MRI with no risk factors for HCC development were recruited. Twenty-seven patients with HCC under the same inclusion criteria were recruited as control. Two radiologists analyzed the images in consensus for morphologic features, enhancement patterns, and hepatobiliary phase (HBP) findings. All results were analyzed using the Mann-Whitney test, two-tailed Fisher exact test, and chi-square test. RESULTS: Patients with AML were younger than those with HCC (48.8 ± 15 years for AML vs. 62.7 ± 14.2 years for HCC, p = 0.008) with female predominance, while most HCC patients were male (75% (9/12) vs. 15% (4/27), p < 0.001). The most prevalent enhancement pattern was arterial enhancement followed by hypointensity at portal or transitional phases for both AMLs (58% (7/12)) and HCCs (74% (20/27)) (p = 0.455). However, during the HBP, AMLs frequently showed more homogeneous hypointensity than HCCs (83% (10/12) vs. 41% (11/27), p = 0.018). When compared with the signal intensity of the spleen, the mean relative signal intensity of the AML was 91.2 ± 15.4%, while in HCCs, it was 128.7 ± 40% (p < 0.001). CONCLUSIONS: Although AMLs showed similar enhancement patterns to HCCs during the dynamic phases of gadoxetic acid-enhanced MRI, using characteristic MR features of AML during the HBP and demographic differences, one can better differentiate AML from HCC.

Renal leiomyoma: a contemporary multi-institution study of an infrequent and frequently misclassified neoplasm.

Renal leiomyoma is an exceptionally rare benign mesenchymal tumor of the kidney predominantly arising in proximity of the renal capsule or pelvis. Its rarity and nonspecific clinical and imaging features may lead to radical or partial nephrectomy on the basis of preoperative suspicion of renal cell carcinoma. The diagnosis of renal leiomyoma is challenging because of the histologic overlap with lipid-poor angiomyolipoma (AML). We conducted a multi-institution study to characterize renal leiomyoma in greater detail. We collected and reviewed 24 cases diagnosed initially as renal leiomyoma in 10 institutions from North America, Canada, and Europe. Immunohistochemical expression of desmin, HMB-45, estrogen receptor (ER), progesterone receptor (PR), and cathepsin K was evaluated. Upon central review, 9 tumors were classified as renal leiomyoma, whereas the remaining were reclassified as AML (n=13), myolipoma (n=1), and medullary fibroma (n=1). All renal leiomyomas were solitary and occurred in female patients (mean age 63 y; range, 44 to 74 y). Tumor size ranged from 0.6 to 7.0 cm (mean 2.9 cm); 7 originated from the renal capsule or the subcapsular area and 1 from a large vessel in the renal sinus. All leiomyomas were diffusely positive for desmin and negative for HMB-45 and cathepsin K; 6/9 (67%) showed diffuse ER and PR expression, and 1 case showed focal ER positivity only. Renal leiomyoma should be included in the histologic differential diagnosis of solid renal masses, particularly in perimenopausal women. The main differential diagnosis is with lipid-poor AML, and cathepsin K plays a key role in distinguishing these 2 lesions.

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

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

Renal angiomyolipoma, fat-poor variant--a clinicopathologic mimicker of malignancy.

Angiomyolipomas, composed of thick-walled blood vessels, smooth muscle, and adipose tissue, belong to the perivascular epithelioid cell neoplasms (PEComas), a family of tumors believed to be derived from perivascular epithelioid cells which co-express smooth muscle and melanocytic markers. Although most angiomyolipomas are benign, a subset of PEComas has metastatic potential. The pathologic and clinical spectrum of these tumors continues to evolve. We sought to evaluate a subset of renal angiomyolipomas with a minimal amount of fat. We studied 48 renal angiomyolipomas in 41 patients (33 females and 8 males). Based on the amount of adipose tissue, the lesions were categorized as fat-poor, fat-average, and fat-rich lesions (<25, 25-75, and >75 % of fat, respectively). Stains for smooth muscle actin, calponin, HMB-45, melanocyte-associated antigen PNL2, estrogen, and progesterone receptor were examined. Four patients (all females) had more than one lesion, four had coexistent uterine leiomyomata, two had coexistent renomedullary interstitial tumor, and males had only single lesions. Except for one woman, all lesions were sporadic. Twenty-nine were fat-poor (60 %) lesions; 8, fat-average (17 %) lesions; and 11, fat-rich (23 %) lesions. The fat content did not correlate with tumor size: the largest fat-poor and smallest fat-rich lesions were >6 and <2 cm, respectively. All lesions stained with smooth muscle actin and HMB-45; 41 % of tumors were positive for estrogen receptor (11 females and 1 male). No patient had metastases (follow-up 2-11 years). In our series, fat content in angiomyolipoma was not associated with tumor size. Fat-poor angiomyolipomas affected predominantly women and were morphologically and radiologically distinct as mimickers of malignancy. Whether they are biologically different from conventional tumors requires further studies.

A case of renal angiomyolipoma with intracardiac extension and asymptomatic pulmonary embolism.

Angiomyolipoma (AML) is the most common benign tumor of the kidney, which is composed of a mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Occasionally, AML may extend into the renal vein or the vena cava, but so far at least, intracardiac extension was rarely reported. We herein present one case of renal AML with intracardiac extension and pulmonary embolism simultaneously in a 52-year-old Chinese female patient. Contrast-enhanced computed tomography revealed a well-demarcated heterogeneous mass in the right kidney which extended into the right atrium through the right renal vein and inferior vena cava and resulted in embolization in the right pulmonary artery. The renal mass together with the thrombus was resected. The renal mass and thrombus in vena cava and right atrium shared the similar histological features: mature adipose tissue, smooth muscle and thick-walled vessels. The thrombus in the right pulmonary artery was mainly composed of mature adipose tissue. These histological features and the result of positive immunostaining for HMB-45, Melan-A, and smooth muscle actin supported the diagnosis of AML. The component of epithelioid cells was less than 5% and mitosis was rarely seen. Intracardiac extension is often observed in the malignant tumor and only seldom seen in benign tumors. Our case reminds the rare possibility of intracardiac extension in renal AML, which may potentially result in fatal complications if not appropriately managed.

Inflammatory angiomyolipoma of the liver: a rare hepatic tumor.

Angiomyolipoma (AML) is a rare mesenchymal neoplasm of the tumor, composed of a varying heterogeneous mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Hepatic AML may demonstrate a marked histological diversity. We herein present one case of hepatic AML exhibiting prominent inflammatory cells in the background, which happened in a 61-year-old Chinese female patient, without signs of tuberous sclerosis. Histologically, the striking feature was the infiltration of numerous inflammatory cells in the background, including small lymphocytes, plasma cells, and eosnophils. The tumor cells were spindled and histiocytoid in shape, with slightly eosinophilic cytoplasm, and arranged along the vessels or scattered among the inflammatory background. Sinusoid structure was obviously seen in the tumor. Mature adipocytes and thick-walled blood vessels were focally observed at the boundaries between the tumor and surrounding liver tissues. The tumor cells were positive immunostaining for HMB-45, Melan-A, and smooth muscle actin. The inflammatory AML should be distinguished from other tumors with inflammatory background such as inflammatory myofibroblastic tumor and follicular dendritic cell tumor and deserves wider recognition for its occurrence as a primary hepatic tumor. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1828633072762370.

Diffuse expression of PAX2 and PAX8 in the cystic epithelium of mixed epithelial stromal tumor, angiomyolipoma with epithelial cysts, and primary renal synovial sarcoma: evidence supporting renal tubular differentiation.

Over the past decade, 3 novel, typically cystic renal neoplasms have been described: angiomyolipoma with epithelial cysts (AMLEC), mixed epithelial stromal tumor (MEST), and primary renal synovial sarcoma (SS). In all 3 neoplasms, the nature of the cystic epithelium is not clear; some have postulated that the cysts represent cystically dilated, entrapped renal tubular epithelium, whereas an alternative interpretation is that the epithelium represents epithelial differentiation by the stromal component of the neoplasm. The latter is supported by the extrarenal location of the epithelium in some cases. PAX2 and PAX8 are tissue-specific transcription factors expressed primarily in the renal and Müllerian systems and also in Wolffian duct structures (such as seminal vesicle). Their expression has not been examined in these lesions. We performed PAX2 and PAX8 immunohistochemistry on representative sections of cases of AMLEC (8 cases), MEST (8 cases), and renal SS (3 cases). The relative percentage and intensity (none, weak, moderate, and strong) of nuclear labeling were evaluated in both the benign adjacent renal tubules and the lesion's epithelial cysts. In the benign kidney, distal convoluted tubules (DCTs) labeled strongly for PAX2 and PAX8, whereas proximal convoluted tubules labeled minimally. The cystic epithelium of all 8 cases of AMLEC, including 5 that protruded beyond the renal capsule into the perirenal fat, demonstrated strong diffuse labeling for both PAX2 and PAX8. We also identified a mimic of entirely extrarenal AMLEC, angiomyolipoma with endosalpingiosis. PAX2 and PAX8 diffusely and strongly labeled the epithelial component of all 8 cases of MEST, including all architectural (phyllodes-like, large cysts, small cysts, clustered microcysts) and virtually all cytologic (hobnail, flat, cuboidal, columnar, apocrine, and clear cell) epithelial variants present. The epithelial cysts of all 3 cases of primary renal SS labeled diffusely and strongly for PAX2 and PAX8. Cyst epithelial labeling intensity was similar to that of renal DCT in all cases. The diffuse labeling for PAX2/PAX8 in the epithelial cysts of AMLEC, taken together with their consistent negativity for estrogen receptor and HMB45, supports the hypothesis that this epithelium represents entrapped, cystically dilated renal tubules that commonly herniate beyond the renal capsule. The diffuse labeling of the cyst epithelium of renal SS supports the previously proposed hypothesis that this cyst epithelium represents entrapped dilated renal tubules in a monophasic spindle cell lesion and not neoplastic epithelial differentiation. The diffuse labeling for PAX2/PAX8 in MEST epithelium, coupled with its usual estrogen receptor negativity, is consistent with the hypothesis that the epithelium of MEST demonstrates renal tubular differentiation and undergoes architectural and cytologic changes as it grows along with the stromal component. Whether this complex epithelium represents entrapped or neoplastic renal tubular epithelium remains an open question.

[Presentation of 2 new cases of cutaneous angiomyolipomas and literature review]. / Angiomiolipomas cutáneos: aportación de dos casos y revisión de la literatura.

We present 2 new cases of cutaneous angiomyolipomas with very similar characteristics, located in the postauricular region of 2 women aged 58 and 52 years. The lesions measured 1.5 cm and 1 cm across and had been present for 5 and 2 years, respectively. Both presented a previously unreported clinical sign: change in size according to the ambient temperature. They had well defined borders and a predominance of smooth muscle and vessels, particularly arteries. In contrast to renal angiomyolipomas, which are often associated with tuberous sclerosis, these angiomyolipomas were negative for melanocytic immunohistochemical markers (human melanoma black-45 antigen and melanoma antigen recognized by T cells 1). The clinical characteristics of the 32 cases published until present are reviewed. The relationship of these tumors with angioleiomyomas and renal angiomyolipomas is discussed.

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

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

T-cell co-regulatory molecule expression in renal angiomyolipoma and pulmonary lymphangioleiomyomatosis.

OBJECTIVES: To investigate the expression of B7-H3 and B7-H1 in renal angiomyolipoma (AML) tumors and the related, devastating syndrome of pulmonary lymphangioleiomyomatosis (LAM). We recently reported the high expression of T-cell co-regulatory B7-H ligands in renal cell carcinoma tumor vasculature and tumor cells. AML is a highly vascular tumor that most frequently emanates from the kidney. Events leading to its pathogenesis remain enigmatic and understudied. METHODS: Immunohistochemical methods were used to assess the tumor expression of B7-H1 and B7-H3 in paraffin-embedded tissues from 110 patients who had undergone partial or radical nephrectomy for renal AML and from 7 patients with LAM who had undergone lung biopsy. RESULTS: B7-H3 was expressed by 100% of the AML and LAM specimens, and B7-H1 expression was detected in only 2.7% of the specimens studied. Both membranous and cytoplasmic B7-H3 expression was noted in the smooth muscle, blood vessel, and lipoid cell components of the tumors; however, no expression was detected in the adjacent, normal parenchyma tissue. B7-H3 staining was noted in a median of 90% (range 20%-100%) of cells from renal AMLs and was independent of patient age (P = .43), sex (P = .27), tumor size (P = .21), and symptomatic presentation (P = .35). CONCLUSIONS: B7-H3 was expressed at high levels in renal AMLs and pulmonary LAM, and B7-H1 was infrequently expressed in these tumors. Additional studies are needed to evaluate the utility of B7-H3 as a diagnostic marker or immune/angiogenic target to improve the management of AML and the potentially devastating condition of LAM, for which effective treatment is lacking.

Lymphatic differentiation in renal angiomyolipomas.

Renal angiomyolipomas are mesenchymal neoplasms with varying proportions of smooth muscle, adipose tissue, and abnormal blood vessels. Although the presence of lymphangiomatous-like foci is frequently noted in large series of angiomyolipoma, lymphatic differentiation has not been previously studied. Twelve angiomyolipomas from 10 patients were identified. All tumors expressed a melanocytic marker, HMB-45 or Melan-A. Twenty-eight paraffin blocks (1-4 per tumor) were stained for lymphatic endothelial cell markers, podoplanin, and D2-40, and the presence and distribution of lymphatic differentiation were recorded. The angiomyolipomas ranged from typical triphasic tumors to leiomyoma-like and lipoma-like tumors. All 12 tumors showed positive staining with podoplanin, and all 6 tumors stained for D2-40 were also positive, indicative of lymphatic differentiation. Lymphatic differentiation was variably observed throughout the tumors. It was most prevalent in myoid areas of the triphasic angiomyolipomas and in the leiomyoma-like variant, but infrequent and widely scattered within the adipose regions of triphasic angiomyolipoma and in the lipoma-like variant. The lymphatics were usually small, often irregularly shaped, and isolated vessels in fat, whereas in myoid regions lymphatics were clustered and in some areas formed a sinusoidal or labyrinth-like pattern. Lymphatics were commonly adjacent to abnormal arteries. However, unlike the lymphatics in the normal renal cortex, a consistent adventitial association was not observed and the clustering around arteries is regarded as reflecting the myoid regions that typically exist in these areas. In conclusion, lymphatic differentiation is common in angiomyolipomas, preferentially located in myoid regions. These data expand the mesenchymal pluripotential profile of renal angiomyolipomas.

The use of the Ki-67 marker in the pathological diagnosis of the epithelioid variant of renal angiomyolipoma.

OBJECTIVE: Epithelioid angiomyolipoma (EAML) is a rare malignant variant of renal angiomyolipoma (AML). There were 34 cases of EAML reported in 25 studies (including this present study) over the past decade. About 68% were females and 32% males. The mean age was 40.1 years, 53% developed metastatic disease after nephrectomy, and eight patients had TSC. All cases are reported positive when stained with HMB-45 which also labels all classical AML. This study evaluates the use of Ki-67 (proliferation marker) in the pathological diagnosis of EAML and distinction from classical AML. METHOD: Immunohistochemical reactions for Ki-67 were generated on multiple representative blocks of tissue obtained from two cases of HMB-45 positive EAML and four cases of classic AML and the percentage of positively staining cells estimated. RESULTS: Both cases of EAML were strongly positive for Ki-67 while all four classic AML were completely negative. CONCLUSION: The Ki67 is a useful marker in which distinguishes the malignant epithelioid variant of AML from classic AML.