[A Case of Retroperitoneal Leiomyosarcoma Resected Radically by Pancreaticoduodenectomy with Vascular Resection].

A 54-year-old woman visited to a doctor nearby medical clinic complaining of loss of appetite. She was diagnosed with right hydronephrosis on abdominal ultrasonography, and referred to our hospital for further examination. Contrast abdominal computed tomography(CT)revealed that a 6.2 cm tumor with a contrast-enhancing effect inside in the retroperitoneum near the lower pole of the right kidney. She was diagnosed with hydronephrosis due to infiltration of the right kidney of a retroperitoneal tumor. The tumor was suspected of invading the duodenum and inferior vena cava, but no obvious lymph node or distant metastasis was observed. Abdominal MRI revealed a tumor showed hyperintensity on T2-weighted and diffusion-weighted images. We performed pancreaticoduodenectomy with inferior vena cava resection and right nephrectomy. The pathological diagnosis was leiomyosarcoma originating from retroperitoneum and pT2, pN0, pM0, pStage ⅢA. The postoperative course was good, and she was discharged 10 days after the operation. Thoracoabdominal CT showed a tumor 4 cm at the hepatic hilum three months after surgery, and EOB-MRI showed many tumors other than the same site, so multiple liver metastases were diagnosed as recurrence. Doxorubicin has been started and is still being treated.

[A Case Report of Resectable Leiomyosarcoma of the Duodenum Origin Invading to the Inferior Vena Cava].

A 40's woman had a complaint of abdominal and back pain. Enhanced CT visualized a large retroperitoneal tumor and huge multiple myomas of the uterus. The tumor was 10cm in diameter and located in the anterior of the inferior vena cava, and progressed from the posterior of the duodenum to the abdominal aortic bifurcation. Diffusion-weighted MR image showed the tumor with high signal intensity. Upper gastrointestinal endoscopy revealed a type 2 tumor at the anal side of the Vater. The patient was performed curativly abdominal total hysterectomy and pancreaticoduodenectomy with inferior vena cava resection. Immunohistochemical examination showed that the tumor cells were negative for CD34 and c-kit, and positive for desmin and a-SMA. The tumor was histopathologically diagnosed as leiomyosarcoma originating from the duodenum.

[A Case of Leiomyosarcoma Arising from the Ovarian Vein Preoperatively Diagnosed with Radiological Imaging].

A 54-year-old woman presented withtransient back pain. She was diagnosed withleiomyosarcoma of the inferior vena cava (IVC) by computed tomography (CT) and was referred to our hospital. Contrastenhanced CT revealed a mass (38×42 mm) located in the retroperitoneal space along the course of the right ovarian vein. The mass compressed the IVC into a crescent shape. A tumor thrombus was also found in the IVC. 18 F-fluoro-2-deoxy-D-glucose positron emission tomography (PET) revealed high uptake at the caudal side of the tumor. These radiological findings strongly suggested the diagnosis of leiomyosarcoma arising from the right ovarian vein. She underwent tumor resection with right nephrectomy, IVC resection, and IVC patch reconstruction without any notable events after surgery. Histopathological diagnosis was leiomyosarcoma arising from the ovarian vein, not from the IVC. Two months after the surgery, CT revealed multiple pulmonary metastases and a single liver metastasis. The patient was referred to another hospital for further treatment. She was treated with chemotherapy and was alive with disease at 14 months after the surgery.

Does the patients age at cancer diagnosis affect microvessels density in uterine sarcoma tissues?

OBJECTIVES: The objective of the study was to retrospectively evaluate the density of vessels exhibiting positive glycoprotein CD34 expression in the uterine leiomyosarcoma tissues and their correlation with the age of patients at the time of tumor diagnosis. MATERIAL AND METHODS: The archival paraffin blocks with the cancer tissues collected from 50 patients suffering from uterine leiomyosarcoma were used together with their clinical and demographic data. The immunohistochemical peroxidase-de-pendent methods were used to detect microvessels with positive CD34 expression. The glycoprotein CD34 expression was evaluated as a density of microvessel showing the positive immunohistochemical reaction (MVDCD34). RESULTS: The negative, statistically significant correlation between the age of patients (at the moment diagnosis) and the MVDCD34+ (R = -0.289, p = 0.042) was found. CONCLUSIONS: The study's findings may suggest that the tissues of younger people constitute a permissive environment for pro-angiogenic factors.

MMPs and angiogenesis affect the metastatic potential of a human vulvar leiomyosarcoma cell line.

Gynaecological leiomyosarcoma (gLMS) represent a heterogeneous group of soft tissue sarcoma, characterized by rare incidence, high aggressiveness and propensity to infiltrate secondary organs, poor prognosis and lethality, because of the lack of biological mechanisms that underlying their progression and effective pharmaceutical treatments. This study was focused on some of the aspects of progression and dissemination of a subtype of gLMS namely vulvar LMS (vLMS). We therefore used a vulvar LMS-derived cell line namely SK-LMS-1, coupled with in vitro and in vivo assays. We observed that SK-LMS-1 cells have a strong invasive capacity in vitro, through the activity of matrix metalloproteinases 2 and 9, while in vivo these cells induce a strong angiogenic response and disseminate to the chick embryo liver. Therefore, we postulate that metalloproteinases are involved in the spreading behaviour of SK-LMS-1. Further investigations are necessary to better understand the molecular and cellular machinery involved in the progression of this malignancy.

[LEIOMYOSARCOMA ARISING FROM OVARIAN VEIN WITH RIGHT HYDRONEPHROSIS: A CASE REPORT].

The patient was a 37-year-old woman who had suffered from repeated pyelonephritis. Computed tomography (CT) of the abdomen revealed a 1.9 cm retroperitoneal mass with compression of the right ureter and hydronephrosis. The patient visited our medical center and admitted. The patient underwent a simple total excision of the mass and end-to-end ureteral anastomosis. The tumor involved right ovarian vein and right ureter. Histopathological diagnosis was leiomyosarcoma of the ovarian vein. At 12 months after operation, local recurrence of surroundings tissue of the right ureter and gallbladder, and inferior vena cava invasion is found. Thus, the patient underwent a right nephroureterectomy with partly resection of the inferior vena cava and en block excision of the gallbladder. While CT revealed no recurrence three months after the operation, adjuvant postoperative combination chemotherapy with gemcitabine and docetaxel was administered. Nine cases of this leiomyosarcoma arising from ovarian vein have been reported in the literature. Leiomyosarcoma arising from ovarian vein with hydronephrosis is a second example.

Defining vascular signatures of malignant hepatic masses: role of MDCT with 3D rendering.

Malignant hepatic masses, both primary and metastatic lesions, have characteristic CT appearances and enhancement patterns. Owing to advances in CT resolution, high-quality vascular maps can be generated with 3D rendering tools to aid hepatic mass evaluation. These renderings enable identification of neovascularity, which is critical for distinguishing malignant from benign lesions, and facilitate identification of small hyperenhancing malignant hepatic tumors. In this review, CT features of malignant hepatic masses are discussed in conjunction with a demonstration of the role for 3D vascular mapping.

CSF1 expression in nongynecological leiomyosarcoma is associated with increased tumor angiogenesis.

Leiomyosarcoma (LMS) is a malignant tumor of smooth muscle cells for which few effective therapies exist. A subset of LMS cases express macrophage colony-stimulating factor (CSF1) and the resultant tumor-associated macrophage (TAM) infiltration predicts poor clinical outcome. Further, TAMs have been shown to increase tumor angiogenesis. Here, we analyzed 149 LMS cases by immunohistochemistry for vascular marker CD34 and show that high microvessel density (MVD) in nongynecological LMS cases significantly predicts poor patient outcome. The majority of high MVD cases were also CSF1-positive, and when combining high MVD with CSF1 expression, an even stronger prognostic correlation with patient outcome was obtained. Gene expression profiling revealed that MVD has a stronger correlation with CSF1 expression than with expression of vascular endothelial growth factor isoforms, which have traditionally been used as markers of angiogenesis and as anti-angiogenic therapeutic targets. Finally, patterns of CSF1 expression and TAM recruitment remained consistent between primary tumors and their metastases, and between primary tumors and those grown as xenografts in mice, highlighting the stability of these features to the biology of LMS tumors. Together, these findings suggest an important role for CSF1 and the resulting TAM infiltration in the pathological neovascularization of LMS tumors and provide a rationale for CSF1-targeted therapies in LMS.

Sunitinib malate in the treatment of recurrent or persistent uterine leiomyosarcoma: a Gynecologic Oncology Group phase II study.

PURPOSE: New agents are needed for patients with metastatic uterine leiomyosarcoma who progress after treatment with doxorubicin or gemcitabine-docetaxel. Agents targeting tumor vasculature have potential for activity in leiomyosarcoma. We aimed to assess the activity of sunitinib in patients with recurrent uterine leiomyosarcoma who had received one or two prior therapies by determining the frequency of patients who survived progression-free for at least 6 months or who achieved objective tumor response. We also aimed to characterize the toxicity of sunitinib and to estimate time-to-progression. PATIENTS AND METHODS: Eligible patients with uterine leiomyosarcoma were treated with sunitinib 50 mg by mouth daily for 4 weeks, with 2 weeks rest. Tumor response and progression-free status were assessed every 6 weeks. RESULTS: Twenty-three of 25 patients enrolled were evaluable for efficacy (two wrong histologies). The median number of cycles was one. Two of 23 patients achieved a partial response (8.7%, 90% two-sided, binomial confidence interval (CI) 1.6-24.9%). Four patients remained progression-free at 6 months (17.4%, 90% two-sided, binomial confidence interval 6.2-35.5%). Toxicities included: grade 3 neutropenia (17.4%); grade 3 thrombocytopenia (13%); grade 3 anemia (17.4%); grades 3-4 lymphopenia (8.7%); grades 3-4 fatigue (30%); grade 3 vomiting/diarrhea (21.7%); skin rash/hand-foot syndrome, grade 2 (13%), grade 3 (4.3%); hypertension, grade 2 (39%), grade 3 (4.3%); grade 2 decrease in cardiac ejection fraction (4.3%), and grade 3 thrombosis (4.3%) Median progression-free survival (PFS) was 1.5 months. CONCLUSION: Sunitinib fails to achieve sufficient objective response or sustained disease stabilization as second- or third-line treatment for uterine leiomyosarcoma.

Microvessel density and VEGF/VEGF receptor status and their role in sarcomas of the pulmonary artery.

Neoangiogenesis, driven by a variety of angiogenic factors, plays an essential role during development and progression of malignant tumors. Vascular endothelial growth factor (VEGF) and its receptors have been designated a central part in the angiogenic process during malignancy. We studied the vascular parameters by means of morphology and morphometry in 7 sarcomas of the pulmonary artery (SPA) and 10 poorly differentiated leiomyosarcomas of soft tissue. Immunohistochemical analysis of VEGF and VEGFR was related to survival and prognosis. The microvessel density (MVD) and intervascular distances (IVD) differed significantly only at sites of necrosis compared to non-necrotic areas in SPA but not for soft tissue leiomyosarcomas. MVD, IVD and vascular surface area (VSA) revealed no difference between SPA and leiomyosarcomas of different origin. We found a more pronounced expression of VEGF in most tumors at sites of necrosis. The receptors were present in a subset of tumor vessels mostly at the tumor border. VEGFR-2 expression was also seen in a subset of tumor cells whereas VEGFR-1 showed only weak expression in some tumors. Local hypoxia seems to induce a higher MVD and a lower IVD at sites of necrosis compared to those areas without necrosis. The presence of necrosis in both sarcoma groups was correlated with the presence of VEGF due to local tumor hypoxia and subsequent up-regulation of VEGFR-2 and VEGFR-1 in tumor vessels as well as tumor cells. Overall and relapse-free survival showed no difference concerning all examined parameters. Thus, microvessel density does not seem to be a prognostic factor in SPA and other sarcomas.

[A case of primary leiomyosarcoma of the liver presenting with acute bleeding].

Leiomyosarcoma is a rare tumor of the liver. It usually arises from many other organs including uterus, gastrointestinal tract, retroperitoneum, and soft tissues. Primary hepatic leiomyosarcoma progresses very slowly and is not associated with chronic liver disease. When the tumor is detected early enough to be treated by operation, the prognosis is favorable. While several cases of primary hepatic leiomyosarcoma have been reported in Korea, there was no case associated with acute bleeding. We report a 80-year old male patient with huge primary hepatic leiomyosarcoma, who presented with acute bleeding and IVC obstruction. The patient was treated by embolization and IVC stenting.

Wild-type p53 suppresses angiogenesis in human leiomyosarcoma and synovial sarcoma by transcriptional suppression of vascular endothelial growth factor expression.

Our recent studies (R. Pollock et al., Clin. Cancer Res., 4: 1985-1994, 1998; M. Milas et al., Cancer Gene Ther., in press, 2000) have shown that the restoration of wild-type (wt) p53 enhances cell cycle control in vitro and inhibits the growth of human soft-tissue sarcoma in severe combined immunodeficient mice. We hypothesized that the antitumor effect of wt p53 overexpression in sarcoma cells is attributable not only to enhanced cell cycle control but also to inhibition of angiogenesis. We evaluated the effect of restoring wt p53 function on angiogenesis in human soft-tissue sarcoma harboring mutant p53. Restoration of wt p53 expression in human leiomyosarcoma SKLMS-1 cells that contain mutant p53 markedly inhibited angiogenesis induced by tumor cells in vivo. Angiogenesis assays using an in vivo Matrigel plug assay demonstrated that less neovascularization in severe combined immunodeficient mice was observed with conditioned medium (CM) from human synovial sarcoma cells expressing wt p53 compared with CM from human synovial sarcoma cells expressing mutant p53. Microvessel density and microvessel counts were lower in tumor xenografts from cells containing wt p53 than in tumor xenografts from cells containing mutant p53. The growth and migration of murine lung endothelial cells were decreased when cells were treated with CM from sarcoma cells expressing wt p53 compared with CM from sarcoma cells expressing mutant p53. The introduction of wt p53 into sarcoma cells containing mutant p53 significantly reduced the expression of vascular endothelial growth factor (VEGF), which is a key mediator of tumor angiogenesis. Stimulation of endothelial cell migration by CM from cells expressing mutant p53 was significantly reduced after anti-VEGF neutralizing antibody was added to the CM. Using luciferase as the reporter of VEGF promoter activity, we found that wt p53 inhibited VEGF promoter activity in SKLMS-1 cells. Deletion analysis defined an 87-bp region (bp -135 to -48) in the VEGF promoter that is necessary for inhibiting VEGF promoter activity by wt p53. The transcription factor Sp1 may be involved in the repression of VEGF promoter activity by wt p53 in SKLMS-1 cells. These data indicated that wt p53 can suppress angiogenesis in human soft-tissue sarcomas by transcriptional repression of VEGF expression.

Combined anti-fetal liver kinase 1 monoclonal antibody and continuous low-dose doxorubicin inhibits angiogenesis and growth of human soft tissue sarcoma xenografts by induction of endothelial cell apoptosis.

Vascular endothelial growth factor (VEGF) and VEGF receptor 2 [fetal liver kinase 1 (Flk-1)/kinase insert domain-containing receptor] have been shown to play a major role in tumor angiogenesis. In this study, we investigated whether anti-Flk-1 monoclonal antibody DC101 could therapeutically inhibit growth and angiogenesis of human soft tissue sarcoma, and we explored its capacity to enhance the tumoricidal effects of doxorubicin. Treatment of well-established leiomyosarcoma SKLMS-1 and rhabdomyosarcoma RD xenografts in severe combined immunodeficient mice with DC101 resulted in significant antitumor activity. In a parallel study, we compared tumor inhibition with continuous low-dose "antiangiogenic" schedule versus once-every-2-weeks high-dose standard schedule of doxorubicin. We found that continuous low-dose treatment inhibited the tumor growth of RD xenografts about 46.5% of that with standard-schedule treatment, but that continuous low-dose treatment did not inhibit the tumor growth of SKLMS-1 xenografts. Notably, combined DC101 and continuous low-dose doxorubicin resulted in more effective growth inhibition of SKLMS-1 and RD xenografts than has been observed with any agent alone in a long-term s.c. tumor xenograft model. The combination therapy was associated with no additional toxicity to the host animal compared with low-dose doxorubicin alone. Histological examination of xenografts showed significantly reduced microvessel counts in the tumors given combined therapy compared with the tumors given either agent alone. These results are consistent with an enhanced inhibition of angiogenesis in vivo by combined DC101 and doxorubicin using Matrigel plug assay. Additionally, DC101 plus doxorubicin directly exerted enhanced inhibitory effects on endothelial cell migration, proliferation, and tube-like formation in vitro. Furthermore, the combination induced an enhanced apoptosis of endothelial cells that was associated with an increase of capase-3 activity. Thus, the inhibition of angiogenesis and induction of endothelial cell apoptosis are likely important mechanisms for the antitumor activity of combined DC101 and doxorubicin. Collectively, our data suggested that anti-VEGF receptor 2 in combination with continuous low-dose doxorubicin may provide a new therapeutic approach for human soft tissue sarcoma in the clinic.

[Complex pelvic and sarcoma surgery with vascular replacement]. / Komplexe Becken- und Sarkomchirurgie mit Gefäßersatz.

Due to optimization of surgical techniques in surgical oncology and vascular surgery, the most modern approaches of anesthesia and intensive care medicine and effective multimodal therapeutic strategies, locally advanced malignant tumors are resected more frequently with a potentially curative intent. In the case of extensive tumors with infiltration of vital vascular structures or of structures which are crucial for extremity preservation, the necessary surgical procedure for complete tumor removal poses a major challenge for the surgeon and incorporates a high risk of perioperative morbidity for the patient. The decision to attempt tumor resection should therefore always be based on a concept considering all aspects of the malignant disease. The treating team should be highly experienced in this complex field of surgery, not only with respect to the surgical approach but also regarding the management of postoperative complications. In this article relevant aspects of decision making, surgical technique and postoperative outcome for malignant tumors involving vascular structures of the retroperitoneum and pelvis are presented.

Platelet and coagulation activation with vascular endothelial growth factor generation in soft tissue sarcomas.

Angiogenesis and activated blood coagulation are involved in tumor growth and metastasis. Although some have suggested that activation of coagulation in tumors is not linked to activation of platelets, no data exist to either support or refute this concept. However, platelet turnover in cancer patients is often increased, and platelets are carriers of angiogenic growth factors. We hypothesized that platelets are involved in tumor-associated angiogenesis. To obtain evidence supporting this hypothesis, we have studied whether the angiogenic and coagulation pathways and platelets are concomitantly activated in cancer patients with soft tissue sarcomas (STSs) using a novel method to detect activated platelets in tumor specimens. Twelve patients with STS were selected on the basis of having intratumoral accumulation of fluid, which was aspirated. These accumulations demonstrated very high concentrations of vascular endothelial growth factor and coagulation factors (including thrombin-antithrombin-complex). Tumor specimens showed dense vascularization with intense vascular endothelial growth factor expression and the presence of activated platelets. Taken together, these results support the concept that angiogenesis, blood coagulation, and platelets are concomitantly activated in STS and support the hypothesis that platelets contribute to tumor-induced angiogenesis.

Different patterns of angiogenesis in sarcomas and carcinomas.

Solid tumors depend on angiogenesis for growth and metastasis. It has been shown that blood vessel density, as determined by counting the number of capillaries in clustered bursts, is a significant prognostic factor in carcinomas. It is unclear, however, whether vessel density is a prognostic factor in sarcomas. In this study, we examined angiogenesis in sarcomas of various grades and compared their vascular patterns to those of carcinomas. Microvessels were identified by von Willebrand factor staining. The matrix of multiple sarcoma and breast carcinoma specimens were extracted and subjected to Western analysis of various angiogenic factors and inhibitors. Metalloproteinase inhibitor presence was also determined by in situ hybridization. In breast carcinomas, capillaries were clustered in bursts within the stroma of the tumor, whereas the sarcoma capillaries were homogeneously distributed in the tumor stroma. Random blood vessel density per high power field in sarcomas did not correlate with patient prognosis. The matrix of sarcomas and carcinomas contained both angiogenic stimulators and inhibitors. Tissue inhibitor of metalloproteinase-1 was found predominantly in fibroblasts and myofibroblasts in the matrix of carcinoma specimens. The difference in the pattern of angiogenesis in sarcomas and carcinomas may be attributable to the presence of fibroblasts and myofibroblasts in carcinomas, resulting in the compartmentalization of bursts of angiogenic factors. The homogeneous appearance of vessel density in sarcomas observed in the present study would be the consequence of the influence of a single compartment.

Microvessels Density in Uterine Leiomyosarcoma.

Uterine leiomyosarcomas (LMS) are rare tumors typically presenting rapid growth and unfavorable outcome. Nowadays the results of uterine LMS treatment do not meet expectations. Angiogenesis is one of processes investigated to be target for future treatment. The aim of the research was to assess microvessels density (MVD) in tumor samples collected from 50 patients with histological confirmed uterine leiomyosarcoma and to investigate statistical relations between MVD, patients survival, and FIGO stage of tumor. The assessment was carried out using immunohistochemistry methods with anti-CD34 antibody. No significant difference in MVD between FIGO stages was observed. Furthermore, contrary to many other malignancies, we found no significant relation between MVD and patients overall and 2-year survival. Results obtained in the study suggest that processes on vascular mimicry and mesenchymal to epithelial transition (MET) may play important role in development of LMS. No statistical relation between MVD and survival leads to conclusion that not only angiogenesis but other mechanisms as well should be taken into consideration in planning future research.

The role of hypoxia related angiogenesis in uterine smooth muscle tumors.

Mechanisms of hypoxia-related angiogenesis are important for uterine smooth muscle tumors. Factors that are related to angiogenesis during hypoxia include vascular endothelial growth factor (VEGF), hypoxia inducible factor 1α (HIF1α), T-cell intracellular antigen1 (TIA1), eukaryotic translation initiation factor 2α (eIF2α) and thrombospondin 1 (TSP1). We investigated immunoreactivities of VEGF, HIF1α, TIA1, eIF2α and TSP1 using an indirect immunoperoxidase method for formalin fixed, paraffin embedded tumors that had been diagnosed as leiomyoma (LMY), cellular leiomyoma (CLM) or leiomyosarcoma (LMS). TSP1 immunoreactivity was scored as moderate, mild or minimal, while VEGF, eIF2α and TIA1 immunoreactivities were scored as mild, moderate and strong in LMY, CLM and LMS samples, respectively. HIF1α immunoreactivity was scored as mild to minimal in LMY, CLM and LMS samples, but showed no statistically significant differences among samples. Although angiogenic factors showed strong immunohistochemical staining intensity in LMS, anti-angiogenic factors showed minimal immunohistochemical intensity. There was no difference in HIF-1α immunoreactivity compared to LMY, CLM and LMS samples. We suggest that HIF1α protein synthesis could be suppressed by eIF2α and TIA1. Furthermore, VEGF could be activated by pathways such as COX2, Ras, NF-ĸB or c-myc instead of HIF1α. Angiogenesis could trigger and accelerate tumor development; therefore, anti-angiogenic therapy could be useful for treatment of tumors.

Uterine epithelioid leiomyosarcomas with clear cells: reactivity with HMB-45 and the concept of PEComa.

In this study, we investigated HMB-45 expression in epithelioid uterine leiomyosarcomas with clear cell areas. From 12 epithelioid leiomyosarcomas, we selected 5 that had: 1) clear cell areas and 2) spindle cell areas that were at least focally positive for desmin and caldesmon. The patients' ages ranged from 47 to 82 years (mean 64 years). Presenting symptoms were uterine bleeding (three), abdominal pain (one), and a pelvic mass (one). There was no history of tuberous sclerosis or lymphangioleiomyomatosis. One patient had stage II disease, one stage III, and three stage IV. All were treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy. Two received radiotherapy, and three were also treated with chemotherapy. The tumors ranged in size from 4 x 3 x 3 cm to 10 x 7 x 6 cm; all had significant cellular atypia, areas of coagulative necrosis, and between 10 and 90 mitoses per 10 high power fields. Vascular invasion was seen in three cases. The epithelioid component varied from 50% to 90% in each case; and the percentage of clear cells was < 1% in one case, 5% in one case, and 10% to 80% in three cases. Smooth muscle actin and desmin were positive in all cases. Four cases were positive for HMB-45 only in the clear cell areas. The tumor with < 1% of clear cells was negative for HMB-45. All were negative for S-100 and c-kit. Three patients died of disease at 9, 30, and 32 months; one patient is alive with progressive disease at 6 months, and one patient (stage II disease) is alive with no evidence of disease at 8 months. Unequivocal uterine epithelioid leiomyosarcomas may have clear cells positive for HMB-45. These tumors might belong to the group of lesion designated as PEComas; however, it is advisable to designate them as uterine leiomyosarcomas. In uterine smooth muscle tumors, some epithelioid cells most likely undergo clear cell changes and become positive for HMB-45. It would be advisable to perform this stain in all epithelioid smooth muscle tumors of the uterus.