Rhabdoid epithelioid leiomyosarcoma of the uterine corpus: a case report and literature review

Epithelioid Leiomyosarcoma of the Uterus: Modern Outcome-based Appraisal of Diagnostic Criteria in a Large Institutional Series

Epithelioid leiomyosarcoma of the uterus is rare and poorly understood. Herein, we characterize a large institutional series of epithelioid leiomyosarcomas aiming to define outcome-determinant diagnostic pathologic features. We also retrieved epithelioid smooth muscle tumors of unknown malignant potential and evaluated a consecutive cohort of leiomyomas for epithelioid subtypes. Of a total of 1177 uterine leiomyosarcomas, 81 (7%) were categorized as epithelioid after review. Epithelioid leiomyosarcoma was strictly defined as having round to polygonal cells with visible pink cytoplasm and round to ovoid nuclei in ≥50% of the tumor volume. Average age was 55 years (range: 26 to 81 y). Median tumor size was 11 cm; tumor was >5 cm in 93% of subjects; 47% were stage 1 at presentation. An infiltrative tumor border was observed, grossly and/or microscopically, in 89% of cases; necrosis was noted in 80%, and vascular invasion in 47%. Mitotic count in 2.4 mm2 (totalling 10 high-power fields, each field 0.55 mm in diameter) ranged from 3 to 100 (median: 26). All cases had moderate, severe or highly pleomorphic atypia. All cases had 2 or 3 of the following: necrosis, at least moderate atypia and ≥4 mitoses in 2.4 mm2. Immunohistochemistry revealed frequent expression of smooth muscle markers including SMA (96%), desmin (95%), and caldesmon (81%). HMB45 and Melan-A were negative in 92% and 100% of cases, respectively. Estrogen and progesterone receptors were expressed by 65% and 54% of tumors, respectively. Follow-up information was available in 68 subjects (median: 23 mo, range: 1 to 254); cancer-related death occurred in 63%, and an additional 15% had recurrent or metastatic disease at last follow-up. Disease-specific survival was shorter in epithelioid leiomyosarcoma patients (median: 44  mo; 35% at 5-y) than in a matched cohort of nonepithelioid leiomyosarcoma (median: 55 mo; 46% at 5-y) (P=0.03). Three epithelioid smooth muscle tumors of unknown malignant potential were evaluated, all <5 cm in size and with atypia and/or irregular borders but mitotic count below the threshold for malignancy. Two of these had follow-up available, which was uneventful. Of 142 consecutive leiomyomas assessed, none had epithelioid morphology as defined. Epithelioid leiomyosarcoma is an aggressive neoplasm, sometimes with a remarkably low mitotic count. In the setting of an epithelioid smooth muscle tumor of the uterus, we postulate that the diagnosis of malignancy is made in the presence of ≥2 of the following: moderate or severe atypia, ≥4 mitoses/2.4 mm2 and tumor cell necrosis. In their absence, the finding of tumor size ≥5 cm, vascular invasion, infiltrative edges or atypical mitoses should be treated with caution, and designation as of at least uncertain malignant potential is warranted.

An Epithelioid Smooth Muscle Neoplasm Mimicking a Signet Ring Cell Carcinoma in the Ovary

A 53-yr-old woman who presented with elevated renal indices was discovered to have a 4.5 cm right renal mass and an incidental 9.7 cm left ovarian mass on imaging studies. She underwent a partial nephrectomy and bilateral salpingo-oophorectomy, revealing a chromophobe renal cell carcinoma and an unusual ovarian neoplasm with epithelioid cells displaying prominent signet ring cell-like morphology. Immunohistochemical analysis of the ovarian neoplasm demonstrated that the tumor cells were diffusely immunoreactive for smooth muscle markers and negative for all tested cytokeratins and epithelial membrane antigen. On the basis of these results, the tumor was interpreted as an unusual epithelioid smooth muscle neoplasm with extensive signet ring cell-like features. Along with primary ovarian signet ring stromal tumors and sclerosing stromal tumors, this example adds epithelioid smooth muscle neoplasms with unusual cytologic alterations to the list of uncommon nonepithelial tumors that can simulate metastatic signet ring cell carcinoma (Krukenberg tumor) in the ovary.

Leiomyosarcoma with partial rhabdomyoblastic differentiation: first case report of primary cardiac origin

BACKGROUND

Leiomyosarcoma occurring as a primary cardiac tumor has been known as an extremely rare condition. Previous studies of leiomyosarcoma with rhabdomyoblastic differentiation have conducted to those arisen from another site, and they indicated a poorer prognosis of this tumor.

CASE PRESENTATION

A 69-year-old woman was referred to our hospital for an operation concerning umbilical hernia. Subsequent imaging examinations before an operation indicated the presence of primary cardiac malignant tumor due to its atypical shape. And then, it was surgically removed. Histopathologically, tumor cells consisted of two different types: spindle and polyhedral cells. Immunohistochemically, it is interesting to note that 2.1% of spindle cells and 23.1% of polyhedral cells showed positive reactivity for myogenin. Furthermore, we performed double-immunostaining for alpha-smooth muscle actin (SMA) and myogenin. The rates of alpha-SMA and myogenin double negative, alpha-SMA single positive, myogenin single positive, and alpha-SMA and myogenin double positive in spindle cells were estimated as 69.1%, 28.8%, 1.1% and 1.0%, respectively. In contrast, the rates in polyhedral cells were estimated as 76.9%, 0.0%, 23.1%, and 0.0%, respectively.

CONCLUSION

Our immunohistochemical evaluation suggested that rhabdomyoblastic differentiation in leiomyosarcoma might be generated not only by de novo generation from mesenchymal cells. To the best of our knowledge, this is the first case of primary cardiac leiomyosarcoma with partial rhabdomyoblastic differentiation.

Heterologous and rare homologous sarcomas of the uterine corpus: a clinicopathologic review

Pure sarcomas of the uterine corpus are uncommon, constituting less than 3% of all malignancies at this site, and most of them are leiomyosarcomas and endometrial stromal sarcomas. Rare histotypes of homologous sarcomas and heterologous sarcomas are occasionally encountered, and the absence of significant accumulated experience with these histotypes at this location may potentially raise diagnostic and patient management difficulties. In this article, the clinicopathologic attributes of all earlier reported sarcomas of the uterine corpus other than leiomyosarcomas and endometrial stromal sarcomas are summarized. Included are embryonal rhabdomyosarcoma, pleomorphic rhabdomyosarcoma, angiosarcoma, alveolar soft part sarcoma, malignant perivascular epithelioid cell tumors (PEComas), osteosarcoma, chondrosarcoma, liposarcomatous tumors, malignant extrarenal rhabdoid tumors, Ewing sarcoma/primitive neuroectodermal tumor, and other rare histotypes. Embryonal rhabdomyosarcoma (20%), Ewing sarcoma/primitive neuroectodermal tumor (17%), angiosarcoma (14%), and pleomorphic rhabdomyosarcoma (13%) appeared to be more common than the others, although there was no single overwhelmingly prevalent histotype in the group. A subset, including embryonal rhabdomyosarcoma, alveolar soft part sarcoma, and PEComas, peak in the premenopausal years, but most of the others were observed in postmenopausal women. Favorable outcomes have been reported for the patients diagnosed with alveolar soft part sarcoma, and the prognosis for their counterparts with PEComa remains a matter of debate. Multimodal therapeutic approaches to contemporary patients with embryonal rhabdomyosarcomas have resulted in significantly improved outcomes. Unfortunately, most of the other sarcomas have been associated with rapid tumor progression and unfavorable patient outcomes. The differential diagnosis for these sarcomas is often extensive and varies by histotype, but their accurate diagnosis fundamentally requires the careful exclusion of biphasic malignancies.

Mucin-secreting gastric adenocarcinoma with Rhabdoid areas

Rhabdoid tumor, first described in kidneys of infants and children, is an aggressive tumor that has been reported in several extrarenal locations. In this report, we describe the case of a 40-year-old patient with gastric adenocarcinoma composed of histologically well-differentiated glandular areas and focal rhabdoid zones. The rhabdoid component showed typical features such as abundant eosinophilic cytoplasm, eccentric nuclei, prominent nucleoli and intense focal positive immunohistochemical cytoplasmic reaction for vimentin. Recognition of the rhabdoid phenotype in gastrointestinal tract neoplasms is important because this feature is associated with poor prognosis and unresponsiveness to conventional therapy.

Atypical teratoid/rhabdoid tumor arising in the setting of a pleomorphic xanthoastrocytoma

We present a case of a 23-year-old man with a tumor containing glial and rhabdoid elements where the former had features of a pleomorphic xanthoastrocytoma (PXA) and the latter had the immunophenotype and genetic profile of an atypical rhabdoid/teratoid tumor. The patient presented with a short history of raised intracranial pressure with rapid deterioration in sensorium. He had a poor outcome despite surgery and radiotherapy. We report this case because of its unusual presentation in adulthood and its occurrence in association with a PXA. We speculate that the PXA was a quiescent tumor and that the secondary genetic alterations, including inactivation of the INI1 gene led to clinical progression.

Mutation of the INI1 gene in composite rhabdoid tumor of the endometrium

Composite rhabdoid tumors are typically adult tumors that contain a component of rhabdoid cells, which are characteristic of the aggressive childhood malignant rhabdoid tumor. Pediatric rhabdoid tumors are characterized by the inactivation of the hSNF5/INI1/SMARCB1 gene, with subsequent loss of expression of the protein. In contrast, only a single composite rhabdoid tumor has demonstrated involvement of the INI1 gene. In our study, INI1 protein expression was studied in 2 uterine carcinosarcomas with rhabdoid components (composite rhabdoid tumors). The rhabdoid component of 1 tumor showed lack of immunoreactivity for the INI1 protein and strong positivity for cyclin D1, whereas the adenocarcinomatous component of the tumor and both components of the second tumor were immunoreactive for the INI1 protein and negative for cyclin D1. Loss of one INI1 allele and a mutation in exon 7 of the remaining allele were detected in the first tumor, consistent with the immunohistochemistry results. Our results demonstrate that deletions and mutations of the INI1 gene can occur also in rare composite rhabdoid tumors of adulthood. Further studies are necessary, however, to determine the prognostic significance of this finding.

Uterine leiomyomas with inclusion bodies: An immunohistochemical and ultrastructural analysis of 12 cases

We describe 12 cases of leiomyoma with intracytoplasmic inclusion bodies, which were detected in a group of 447 leiomyomas examined at our institution between December 2005 and March 2006. Ten of these tumors were typical leiomyomas, and two cases represented atypical (bizarre) leiomyoma. In some cases, the presence of intracytoplasmic inclusion bodies resulted in a rhabdoid or skeletal muscle-like appearance of the tumor cells. Ultrastructurally, there were two types of inclusions. One of them consisted of an abnormal aggregation of intermediate and actin filaments. Another type of inclusions was composed of dense granular material without an apparent fibrillar structure. The ultrastructure of the inclusions correlates with immunohistochemical and histochemical stainings. The inclusions with apparent fibrillar arrangements were PAS negative, stained red by trichrome, and were, at least at the periphery, actin-, desmin-, and h-caldesmon-positive. The dense granular inclusions were at least focally PAS-positive, stained red by trichrome, and were negative immunohistochemically. The intracytoplasmic inclusions were found in atypical (bizarre) leiomyomas of the uterus and occasionally in epithelioid leiomyomas and leiomyosarcomas. However, to the best of our knowledge, these inclusions have not been found in typical uterine leiomyomas to date.

Skeletal Muscle-like and Rhabdoid Cells in Uterine Leiomyomas

We describe eight unusual uterine leiomyomas characterized by a component of cells that suggested skeletal muscle differentiation or resembled the rhabdoid cells of extrarenal rhabdoid tumors. All of the tumors were referred because of problems in differential diagnosis, particularly distinction from an epithelioid smooth muscle tumor, a smooth muscle tumor of uncertain malignant potential, or a tumor with skeletal muscle differentiation. The patients were aged 27 to 50 (mean, 38) years, and the presenting clinical features and gross appearance of the tumors were similar to those of typical uterine leiomyomas. On microscopic examination, seven of the tumors were well circumscribed, whereas one showed slight irregularity of its margin. The characteristic feature of the tumors was a variable number of rounded, polygonal, or strap-shaped cells with abundant deeply eosinophilic cytoplasm and fibrillar, or occasionally hyaline, intracytoplasmic globules. Cytoplasmic cross-striations were not identified. The cells usually had eccentric, round-to-oval nuclei with conspicuous nucleoli. A variable number of the rhabdoid/skeletal muscle-like cells, as well as cells without these features, contained multiple or multilobed, pleomorphic, hyperchromatic nuclei, thus qualifying the tumors as leiomyomas with bizarre nuclei. Foci of hydropic change were present in all of the tumors. The mitotic index was low (<1 mitotic figure/10 high-power fields) and necrosis was absent in all the tumors. The rhabdoid/skeletal muscle-like cells were immunoreactive for desmin and h-caldesmon, but not for cytokeratin (AE1/AE3) or skeletal muscle markers (myoglobin, Myo-D1, or myogenin). Intracytoplasmic whorls of intermediate filaments were observed in the cells of one case examined by electron microscopy; there was no ultrastructural evidence of skeletal muscle differentiation. The histologic, immunohistochemical, and ultrastructural features indicated that the peculiar cells in these leiomyomas likely represented smooth muscle cells with an unusual phenotype rather than the cells of uterine tumors with skeletal muscle differentiation, extrarenal rhabdoid tumors, or epithelioid smooth muscle tumors. An association with leiomyomas with bizarre nuclei also was suggested.

Proximal-Type Epithelioid Sarcoma: Report of Two Cases in the Perineum

The authors report two cases of perineal proximal-type epithelioid sarcoma in middle-aged men, age 51 and 43 years old. Both tumors were located in the right side. In the first patient a 7.5-cm, well-encapsulated tumor was completely excised. The second patient was a referral case with incomplete excision, but the computed tomography scan and magnetic resonance imaging showed a 14-cm nonencapsulated tumor involving the soft tissues of the inner thigh and perineum, as well as metastasis in right inguinal and retroperitoneal lymph nodes. Both neoplasms had a predominant solid pattern alternating with occasional discohesive areas. Both were composed of large oval to polygonal cells with vesicular nuclei, conspicuous nucleoli, and amphophilic to eosinophilic cytoplasm. Rhabdoid phenotype was identified in the second case only. The first neoplasm displayed 15% necrosis, 7 mitoses per 10 high-power field, focal vascular invasion, and no extracapsular invasion. The other exhibited 60% necrosis, 12 mitoses per 10 high-power fields, extensive vascular invasion, no distinct capsule, and invasion of the surrounding fatty tissue. Both were positive for vimentin, cytokeratin, epithelial membrane antigen, and CD34. Muscle-specific actin was negative in the first case and focally positive in the second. CD56 was positive in the second case and negative in the first case. Desmin, CD45, CD30, factor VIII, CD31, S100, HMB45, calretinin, and synaptophysin were negative in both. Since proximal-type epithelioid sarcoma can be confused with a number of other soft tissue tumors with epithelioid and/or rhabdoid features, the authors emphasize the immunohistochemical differential diagnosis.

INI1 expression is retained in composite rhabdoid tumors, including rhabdoid meningiomas

Rhabdoid cells are encountered in specific entities, such as malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor, as well as in composite rhabdoid tumors derived secondarily from other tumor types. Although rhabdoid tumors are uniformly aggressive, distinction of the entity from the phenotype remains important for its therapeutic implications. The majority of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors affect infants and young children, harbor chromosome 22q deletions, and inactivate the INI1/hSNF5/BAF47 tumor suppressor gene on 22q11.2. In contrast, most composite rhabdoid tumors are diagnosed in adults, with FISH detectable 22q losses the exception rather than the rule. However, this assay remains limited since 22q dosages are maintained in 20-30% of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors. Furthermore, chromosome 22 losses are common in some parent tumor types, particularly meningiomas. The recently developed INI1 antibody shows loss of nuclear expression in malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors, though its status in composite rhabdoid tumors is largely unknown. Therefore, we utilized immunohistochemistry and FISH to study INI1 expression and 22q dosages, respectively, in 40 composite rhabdoid tumors, including 16 meningiomas, 15 carcinomas, three melanomas, two sarcomas, two glioblastomas, and 1 neuroblastoma. Approximately 70% of rhabdoid meningiomas had a 22q deletion, but this was rare in other tumor types. Except for one retroperitoneal leiomyosarcoma, nuclear INI1 expression was retained in all composite rhabdoid tumors, including meningiomas with 22q deletion. Therefore, we conclude that INI1 immunohistochemistry is a relatively simple, sensitive, and specific technique for distinguishing malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor from composite rhabdoid tumor.

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.