Myxoid leiomyosarcoma of the uterus

Burch D M & Tavassoli F A
(2011) Histopathology  59 , 1144–1155
Myxoid leiomyosarcoma of the uterus Aims: Recent guidelines have suggested the presence of tumour cell necrosis (TCN), atypia and mitotic index as major features in the distinction of myxoid leiomyosarcomas (MLMSs) from myxoid leiomyomas. The aim of this study was to focus on an invasive growth pattern as a significant feature in this distinction in the absence of TCN. Methods and results: Twelve uterine smooth muscle tumours with myxoid change in ≥60% of the lesion were interpreted as MLMS on the basis of the presence of focal mild atypia as well as one or more of the following features: (i) infiltrative growth pattern; (ii) vascular invasion; (iii) mitotic index of ≥5 mitotic figures (m.f.)/50 high‐power fields (HPFs); and (iv) a combination of at least focal severe atypia and at least 2–4 m.f./50 HPFs. Unequivocal TCN was not evident in any of these tumours. The various morphological features were correlated with outcome. With follow‐ups ranging from 19 to 113 months (mean 60 months), five of the 12 women developed recurrences, and two of them died. Nine of the 12 tumours had an infiltrative growth pattern, and all five recurrent tumours were from this group. Conclusion: In the absence of TCN, an infiltrative margin is a major factor related to the potential for aggressive behaviour of MLMS.     

Myxoid leiomyosarcoma

A series of 13 myxoid leiomyosarcomas (LS) is presented. Seven were from genital and six from extragenital sites and most tumours were large. The myxoid matrix in some tumours separated individual tumour cells; occasionally the myxoid areas were trabecular in shape, resulting in a plexiform tumour pattern; in other tumours there were many closely spaced small mucoid pools which produced a pseudoglandular pattern; in one tumour the pools were large and confluent, and macroscopically evident as gelatinous areas. Four patients who were followed up and whose tumours had shown an absent or very low mitotic rate, nevertheless developed recurrences or metastases; hence a low mitotic count was an unreliable prognostic criterion. The myxoid LS studied did not differ in clinical behaviour and prognosis from the more common solid counterparts. Myxoid LS should be included in the differential diagnosis of any myxoid malignant soft tissue tumour.     

Myxoid leiomyosarcoma of the uterus: a case report and review of the literature.

A case report of myxoid leiomyosarcoma of the uterus in a 54-year-old woman is presented as a rare variant of uterine sarcoma. Only 14 cases have been described in the literature. These tumors have a striking myxoid appearance and exhibit highly malignant behavior despite their low mitotic index. Although it is difficult to establish the nature of the neoplastic cells in the myxoid areas, both light microscopical and immunohistochemical characteristics showed features of smooth muscle cells in some of the cellular areas. Our patient had a tumor which arose in association with hyalinized benign leiomyomatous lesion. Like other reported cases of myxoid leiomyosarcoma, the tumor behaved aggressively.     

Myxoid leiomyosarcoma of the liver

This is the first report of a myxoid leiomyosarcoma arising in a cirrhotic liver. The tumor was resected from a 64-year-old man. On gross examination, it was soft and hemorrhagic. The tumor was composed of deceptively benign-looking smooth muscle cells with clear cytoplasm suspended in a myxoid stroma with foci of hemorrhage. Immunohistochemistry and electron microscopy confirmed that this was a smooth muscle cell neoplasm. The abundance of glycogen and ultrastructural signs of smooth muscle differentiation were considered consistent with an immature smooth muscle cell phenotype consistent with the diagnosis of myxoid leiomyosarcoma. Since myxoid leiomyosarcomas are aggressive tumors, it is important to recognize them histologically and also bear in mind that these tumors can occur even in unusual extrauterine locations such as a cirrhotic liver.     

Myxoid leiomyosarcoma of the urinary bladder

A 16-year-old male patient with hematuria was found to have a 3-cm mass on the right posterolateral wall of the urinary bladder. After a biopsy specimen disclosed a myxoid tumor, a partial cystectomy was performed. The specimen contained a gelatinous tumor that, on microscopic examination, was a myxoid leiomyosarcoma similar to the neoplasm recently described in the uterus and several other locations. This tumor, which is the first of its type (to our knowledge) reported to occur in the bladder, must be distinguished from other neoplasms and nonneoplastic lesions that occur in this organ. The patient is well two years postoperatively.     

Myxoid leiomyosarcoma of the uterine cervix

The clinical and pathological features of 11 cases of regressing keratoacanthoma are presented. These lesions were from sun-exposed skin of individuals between the ages of 58 and 92 years and were of short clinical duration (2–12 months). Histologically, these lesions showed similar features and consisted of symmetrical shallow cup-shaped invaginations of thin atrophic epidermis with overhanging edges. The underlying papillary dermis demonstrated variable degrees of inflammatory infiltrate and scarring. It is important to recognize these features as representing regressed keratoacanthoma as they may be confused with other unrelated skin conditions.     

Myxoid endometrial stromal sarcoma of the uterus

A rare case of a myxoid type of endometrial stromal sarcoma of the uterus in a 41-year-old woman is reported. A tumor was found in the myometrium and was well circumscribed, measuring 9 x 7 x 7 cm in size. The tumor was mainly composed of a hypocellular area with tumor cells separated by prominent myxoid stroma. The tumor cells were spindle-shaped and resembled endometrial stromal cells. Numerous small thin-walled vessels were seen throughout the tumor. Immunohistochemically, the tumor cells were diffusely stained for estrogen and progesterone receptors and CD10, and focally and weakly for HHF35, alpha-smooth muscle actin and desmin, but not stained for h-caldesmon. These results indicated that the tumor originated from endometrial stromal cells. The tumor had an increased mitotic activity (MIB-1 labeling index: 1-10%), and focally showed nuclear pleomorphism. Thus, this tumor had a malignant potential and was diagnosed as a myxoid type of low-grade endometrial stromal sarcoma. The patient is currently well with no evidence of local recurrence or metastasis 21 months after the operation. This case indicates a wide morphological spectrum of endometrial stromal tumor. A myxoid endometrial stromal sarcoma should be considered in the different diagnosis of the intramural myxoid tumors in the uterus.     

Myxoid mesenchymal tumors of uterus: endometrial stromal and smooth muscle tumors, myxoid variant

Four myxoid variant of uterine mesenchymal tumors are reported. One was a low grade stromal sarcoma with infiltrative margins and the others were well circumscribed tumors corresponding to an endometrial stromal nodule and two leiomyomas. They were hypocellular neoplasms composed of stellated cells with an abundant Alcian Blue positive myxoid matrix. The myxoid nature of the neoplasms obscured their cellular nature and made the distinction between smooth muscle and endometrial stromal tumors difficult. Endometrial stromal tumors, showed very focal areas of small basophilic cells, characteristic of endometrial stroma. The diagnosis was based on the presence of a spiral arteriolar network, a CD10 positivity as well as the absence of h-caldesmon and desmin expression. The two myxoid leiomyomas showed more spindle cells and a desmin expression while h-caldesmon was negative and CD10 focally positive in both cases. Myxoid variant of endometrial stromal tumors does not necessarily exhibit the typical morphology of endometrial stroma. They may demonstrate morphological features of smooth muscle tumors in the uterus. Also, myxoid changes in uterin smooth muscle tumors may modify the classical immunoreactivity of smooth muscle markers in these tumors and make it difficult to distinguish between benign and malignant neoplasms. An immunohistochemical panel of antibodies including CD10, h-caldesmon and desmin may help in establishing the correct diagnosis.     

Myxoid leiomyosarcoma of the ovary: Analysis of three cases

The first three cases of myxoid leiomyosarcoma occurring in the ovary are reported. Two cases in stage III were found in postmenopausal patients and a further case was found in stage I in a 32-year-old. All masses were large and gelatinous with cystic change, necrosis, and hemorrhage, but both uteri and ligaments and contralateral adnexa appeared normal. Microscopically, the tumors showed a predominantly reticular meshwork of elongated cells surrounded by abundant basophilic material. While electron microscopy proved inconclusive due to nondifferentiation, the use of monoclonal antibodies against smooth muscle actin demonstrated a smooth muscle type of differentiation. The differential diagnosis of this rare ovarian condition includes other myxoid ovarian lesions, such as ovarian edema, myxoma, endodermal sinus tumors, and the sarcomatous component of malignant mixed müllerian tumor and carcinosarcoma, as well as lymphovascular tumors. Since mitotic count due to decreased cellular density is unusually low in myxoid leiomyosarcoma, capsular rupture and clinical stage seem to be more reliable prognostic markers. The highly aggressive behavior of myxoid leiomyosarcoma parallels that of typical ovarian leiomyosarcoma. Two of the three patients in this series died of tumor at 13 and 24 months after diagnosis; the other patient is free of disease at 3 years after diagnosis.     

The clear cell variant of epithelioid intravenous leiomyomatosis of the uterus: Report of a case

A case of very rare uterine clear cell epithelioid leiomyomatosls Is reported. The patient presented with a recurrent pelvlc mass after hysterectomy 2 years earlier. The recurrent tumor was located mainly In the vessels of the broad llgament as worm-like plugs. The revlewed hysterectomy speclinen showed a typical multi-lobuiated intramural mass together with worm-like plugs wlthin the myometrlal vessels. Computer tomography exhlbited metastatic nodules In both lungs. According to an histologlcal examlnatlon, all the tumor cells were of epltheliold type and contalned abundant clear cytoplasm. Characteristic large, thick-walled blood vessels were observed. Immunohisto-chemical staining and ultrastructural examinatlon sup ported smooth-muscle origin In this case. Electron mlcrosmplc study revealed that the clear cytoplasm was attributed to the presence of numerous dllated mitochondria that had lost their crlstae. The patient is still alive wlth the disease 28 months after surgery.     

Myxoid epithelioid sarcoma: clinicopathologic analysis of 2 cases

In the nearly 4 decades since its original delineation as a distinct clinicopathologic entity, several morphologic variations of epithelioid sarcoma have been described. Proximal, angiomatoid, and fibroma-like variants have been reported, as have cases displaying significant hyalinization, calcification, and/or ossification. Furthermore, it has long been recognized that epithelioid sarcoma may display focal myxoid change. Herein, the authors describe 2 examples of epithelioid sarcoma that displayed diffuse myxoid change. Both cases were otherwise typical, both morphologically and immunophenotypically, of epithelioid sarcoma. The tumors in both cases were localized, and the patients were treated with wide local excision followed by adjuvant radiotherapy. The patients are free of disease recurrence after 25 and 37 months of follow-up. Differential considerations that may arise because of the composite of morphologic and immunophenotypic findings noted in these cases are discussed, especially if encountered in a small biopsy. These cases further expand the morphologic spectrum of epithelioid sarcoma.     

Unusual clear cell variant of epithelioid mesothelioma.

Clear cell mesothelioma is an extremely rare neoplasm of the pleura, which can easily be mistaken for a metastasis of clear cell carcinoma to the pleura. We report here the histochemical, immunohistochemical, and ultrastructural aspects of a new case of clear cell pleural mesothelioma in a 52-year-old man with no known asbestos exposure. He was admitted to the hospital for recurrent pleural effusion, which was negative for neoplastic cells at the cytologic examination. A partial decortication of the right pleura was performed. The morphologic, immunohistochemical, and ultrastructural features reported for this case are consistent with the diagnosis of clear cell mesothelioma. The differential diagnosis and immunohistochemical features in comparison with other clear cell neoplasms are discussed.     

Myxoid variant of primary cutaneous malignant melanoma

We report a rare case of primary cutaneous myxoid melanoma. Histologically, the tumour was composed of spindle and stellate-shaped cells, embedded in a myxoid stroma. Positivity for S-100 protein and the presence of melanosomes were demonstrated in the tumour. Primary cutaneous myxoid melanoma is rare. This is the second report of such a case.     

Histological and immunohistochemical observations of dedifferentiated leiomyosarcoma of the uterus.

A case of dedifferentiated leiomyosarcoma of the uterus was examined using immunohistochemistry. The tumor arose in the myometrium, and was a whitish large nodule with hemorrhage and necrosis. Histologically it was a well differentiated leiomyosarcoma with foci showing epithelioid pattern, and in part resembling malignant fibrous histiocytoma (MFH) and giant cell tumor (GCT). Additionally, small round neoplastic cells arranged in an alveolar manner, simulating alveolar rhabdomyosarcoma, were seen in some areas. Neoplastic cells in well differentiated areas expressed desmin, muscle-specific actin and LeuM1, whereas those in epithelioid and poorly differentiated areas lacked these antigens. Instead, tumor cells in epithelioid and small round cell areas were positive for keratin. Interestingly, most tumor cells in well differentiated, epithelioid and small round cell areas were also positive for MB1. However, tumor cells in GCT- and MFH-like areas reacted with none of the antibodies used. Ultrastructurally, some tumor cells possessed various amounts of microfilaments with or without dense patches, whereas others lacked them. These findings suggest that the divergent antigen expression was attributable to different levels of differentiation, and that poorly differentiated components had lost their native features.     

Sclerosing variant of epithelioid angiomyolipoma

Presented herein are two unusual epithelioid angiomyolipomas (AML) displaying prominent stromal sclerosis. Both patients were middle-aged women without a clinical history of tuberous sclerosis. One patient (case 1) had a 2 cm lesion arising in the renal cortex, and another (case 2) had a pararenal retroperitoneal tumor measuring 13 cm. Both tumors were composed of sheets or nests of polygonal epithelioid or short spindle cells having uniform round to oval nuclei and eosinophilic cytoplasm with cords of hyalinized sclerotic stroma between them. The tumor in case 2 had small areas of mature-looking fat cells. Immunohistochemically, epithelioid tumor cells were diffusely positive for actins and desmin in both cases, and melanoma antigen recognized by T cells (MART)-1 was positive in patient 2. Scattered HMB-45-immunoreactive cells were identified in the sclerotic cords of both tumors, but epithelioid tumor cells were essentially negative for HMB-45. The characteristic clinicopathological and immunohistochemical features of the present cases are analogous to a subset of epithelioid AML or sclerosing perivascular epithelioid cell tumors previously reported.