Pericytoma with t(7;12) and ACTB-GLI1 fusion arising in bone.

Cytogenetic analysis of a primary bone neoplasm with pericytic features in a 67-year-old man revealed a t(7;12)(p22;q13) among other karyotypic abnormalities. Subsequent molecular studies confirmed the presence of an associated ACTB-GLI1 fusion transcript. An identical 7;12 translocation is known to characterize a discrete group of soft tissue tumors belonging to the myopericytic category termed pericytoma with t(7;12). To the best of our knowledge, this is the first case of pericytoma with t(7;12) arising in bone. Cytogenetic and molecular analyses were useful, if not essential, in classifying this rare diagnostic entity.

Vascular management in rotationplasty.

The Van Nes rotationplasty is a useful limb-preserving procedure for skeletally immature patients with distal femoral or proximal tibial malignancy. The vascular supply to the lower limb either must be maintained and rotated or transected and reanastomosed. We asked whether there would be any difference in the ankle brachial index or complication rate for the two methods of vascular management. Vessels were resected with the tumor in seven patients and preserved and rotated in nine patients. One amputation occurred in the group in which the vessels were preserved. Four patients died secondary to metastatic disease diagnosed preoperatively. The most recent ankle brachial indices were 0.96 and 0.82 for the posterior tibial and dorsalis pedis arteries, respectively, in the reconstructed group. The ankle brachial indices were 0.98 and 0.96 for the posterior tibial and dorsalis pedis arteries, respectively, in the rotated group. Outcomes appear similar using both methods of vascular management and one should not hesitate to perform an en bloc resection when there is a question of vascular involvement.

Concomitant arterial and venous reconstruction with resection of lower extremity sarcomas.

INTRODUCTION: Limb salvage can now be achieved in many cases of lower extremity sarcoma. Obtaining disease-free margins may require resection of adjacent vascular structures. We present our experience with a consecutive series of patients undergoing resection of lower extremity sarcomas en block with the artery and vein, focusing on the mid- and long-term outcomes of their vascular reconstruction. METHODS: Records were reviewed retrospectively for patient age, tumor location and type, procedure, and early and late outcomes. Between 1991 and 2004, 10 children (mean age 12 years, range 6-18 years) and 9 adults (mean age 48 years, range 24-73 years) underwent wide resection of lower extremity sarcomas to include the involved arterial and venous segments. All children had bone sarcomas, and because of their skeletal immaturity, they were treated with rotationplasty--a type of intercalary amputation that removes the distal thigh, knee, and proximal tibia while preserving the distal leg and foot. In rotationplasty, the distal residual limb is preserved, rotated 180 degrees, and attached to the thigh, positioning the ankle at the level of the former knee joint. In these cases, the residual vessels were reconstructed by primary anastomosis. All of the adults except one had soft tissue sarcomas; the resected vessels were reconstructed with contralateral saphenous vein. In all cases, the operative approach included shunting of artery and vein during tumor removal and orthopedic reconstruction. RESULTS: The mean follow-up was 5.7 years. Three patients died of metastatic disease, and one died from a postoperative pulmonary embolism. No patient had local recurrence. Two patients ultimately required above-knee amputation: one child for tissue loss secondary to reperfusion injury, and one adult because of graft thrombosis secondary to progression of peripheral arterial disease. Two patients required early re-exploration for perioperative graft thrombosis. Both required replacement of saphenous vein conduits with polytetrafluoroethylene (PTFE) prosthetic graft; one of the PTFE grafts became infected. CONCLUSIONS: Limb salvage can be achieved in the majority of patients who have lower extremity sarcomas even when en bloc resection includes the artery and vein. Intraoperative shunting can limit ischemia and is especially useful when immediate vascular repair is delayed by orthopedic reconstruction. The long-term patency rate of the reconstructed vessels is high. Saphenous vein is the preferred conduit when it is of adequate caliber.

Monoallelic deletion of the p53 gene through chromosomal translocation in a small cell osteosarcoma.

Small cell osteosarcoma is a rare bone tumor of high-grade malignancy that most often arises in the metaphysis of long bones in the second decade of life. Cytogenetic and molecular genetic findings in small cell osteosarcoma are poorly defined. Conventional cytogenetic analysis of a small cell osteosarcoma arising in the proximal tibia of a 9-year-old male revealed a diploid chromosomal complement with complex structural rearrangements involving chromosomes 6, 16, and 17. Immunohistochemical assessment of p53 protein expression revealed nuclear p53 immunoreactivity in approximately 15% of the neoplastic cells. Subsequent fluorescence in situ hybridization (FISH) analyses confirmed loss of the p53 gene locus on the derivative chromosome 17 homolog and were negative for amplification of the MDM2, CDK4, c-MYC, HER-2/neu, CCND1, and COPS3 gene loci. To the best of our knowledge, this represents the first demonstration of monoallelic deletion of p53 in small cell osteosarcoma, suggesting that p53 alterations may play an important role in the development of small cell osteosarcoma as well as conventional osteosarcoma.

Use of a novel FISH assay on paraffin-embedded tissues as an adjunct to diagnosis of alveolar rhabdomyosarcoma.

A valuable diagnostic adjunct and important prognostic parameter in alveolar rhabdomyosarcoma (ARMS) is the identification of translocations t(2;13)(q35;q14) and t(1;13)(p36;q14), and the associated PAX3-FKHR and PAX7-FKHR fusion transcripts, respectively. Most RMS fusion gene type studies have been based on reverse transcriptase-polymerase chain reaction (RT-PCR) detection of the fusion transcript, a technique limited by RNA quality and failure of devised primer sets to detect unusual variants. As an alternative approach, we developed a fluorescence in situ hybridization (FISH) assay that can: (1) distinguish between the two most common ARMS-associated fusion genes; (2) identify potential unusual variant translocations; (3) assess histologic components in mixed alveolar/embryonal RMS; and (4) be performed on paraffinized tissue. FISH analyses of 75 specimens (40 ARMS, 16 ERMS, 8 mixed ARMS/ERMS, and 11 non-RMS tumors) using selected cosmid clone, bacterial, P1-derived, and yeast artificial chromosome probe sets were successful in all but two cases. Among specimens with informative results for both FISH and RT-PCR or standard karyotyping, PAX/FKHR classification results were concordant in 94.6% (53/56). The three discordant cases included one exhibiting a t(2;13) by FISH that was subsequently confirmed by repeat RT-PCR, a second showing a rearrangement of the PAX3 locus only (consistent with the presence of a PAX3 variant translocation), and a third revealing a t(2;13) by FISH that lacked this translocation cytogenetically. Both alveolar and embryonal components of the mixed ARMS/ERMS subtype were negative for PAX3, PAX7, and FKHR rearrangements, a surprising finding confirmed by RT-PCR and/or conventional karyotyping. These data demonstrate that FISH with newly designed probe sets is a reliable and highly specific method of detecting t(1;13) and t(2;13) in routinely processed tissue and may be useful in differentiating ARMS from other small round cell tumors. The findings also suggest that FISH may be a more sensitive assay than RT-PCR in some settings, capable of revealing variant translocations.

Cytogenetic findings in clear cell chondrosarcoma.

Clear cell chondrosarcoma is a rare cartilaginous tumor of low-grade malignancy that most often arises in the epiphysis of long bones in the third and fourth decades of life. Cytogenetic studies of clear cell chondrosarcoma are few. In this study, the cytogenetic findings of 4 cases of clear cell chondrosarcoma are presented. Clonal chromosomal abnormalities were detected in 3 cases. A tumor specific anomaly was not identified, however, extra copies of chromosome 20 and loss or rearrangements of 9p appear to be recurrent.

C-erb-B2 (HER2/neu) expression in synovial sarcoma of the head and neck.

BACKGROUND: Synovial sarcoma is a malignant mesenchymal tumor composed of varying proportions of spindle and epithelial cell components. Because of the histologic and immunohistochemical similarity of synovial sarcoma to epithelial carcinomas, we hypothesized that the human epithelial growth factor receptor 2 (C-erb-B2, also termed HER2/neu) may contribute to the tumor phenotype and provide a new therapeutic target for this soft tissue tumor. METHODS: Three head and neck, one chest wall, and seven extremity synovial sarcomas were evaluated for C-erb-B2 (HER2/neu) expression by immunohistochemistry, Western immunoblotting, and fluorescence in situ hybridization (FISH). RESULTS: The head and neck cases demonstrated immunohistochemically strong positive staining, whereas tumors from other anatomic locations showed neither positive nor cytoplasmic restricted staining. Antigen-targeted antibody therapy (trastuzumab) was initiated in two patients. CONCLUSIONS: These results demonstrate that C-erb-B2 (HER2/neu) may play a role in the tumorigenesis of synovial sarcoma; and, therefore, antigrowth factor therapies may provide a previously unrecognized pharmaceutical approach to soft tissue tumors. The data also suggest that although synovial sarcoma of the head and neck and synovial sarcoma of the extremities have similar morphologic features, they may be clinically and mechanistically distinct entities.

Promises and pitfalls of stem cell therapy for promotion of bone healing.

UNLABELLED: There is promise in combining stem cells with allogeneic bone matrix to promote bone healing. Murine bone marrow, peripheral blood, and compact bone cells were transplanted ectopically under the kidney capsule in mice, alone or in combination with allogeneic matrix products: powder and putty to determine their bone forming potential in comparison to transplanted femoral bone fragments and long-term cultured bone marrow cells. The end point was the amount of bone formed as determined by quantitative histology. Mononuclear cells from marrow, peripheral blood, or bone alone transplanted under the kidney capsule did not form bone. Mononuclear cell populations did not combine readily with matrix products and there was in vivo migration of the transplanted combinations. Kidney subcapsular transplanted cultured bone marrow cells formed bone in proportion to the culture period, but after 9 weeks, the extent was only 20% by area of that of similarly transplanted femoral bone fragments. An inductive stimulus for bone formation seemed necessary. Osteoprogenitor cells were not detected in significant numbers in blood unless high doses of cytokines were administered. A better definition of the optimal cell populations and manipulations required for promotion of bone healing is needed along with new (transplant) models that allow for cell tracking. Much work remains to overcome current pitfalls in the use of stem cells to promote allograft integration and bone healing. LEVEL OF EVIDENCE: Therapeutic study, Level V (expert opinion). See the Guidelines for Authors for a complete description of levels of evidence.

Aneurysmal bone cyst variant translocations upregulate USP6 transcription by promoter swapping with the ZNF9, COL1A1, TRAP150, and OMD genes.

Aneurysmal bone cysts (ABC) are locally aggressive bone tumors that often feature chromosome 17p13 rearrangements. One of the ABC 17p13 rearrangements--t(16;17)(q22;p13)--was recently shown to create a CDH11-USP6 fusion in which the USP6/TRE17 oncogene is overexpressed through juxtaposition with the CDH11 promoter. Herein, we characterize four different ABC translocations involving 17p13, and we show that each is associated with a novel USP6 fusion oncogene. Specifically, we demonstrate that t(1;17), t(3;17), t(9;17), and t(17;17) result in USP6 fusions with TRAP150 (thyroid receptor-associated protein 150), ZNF9 (ZiNc Finger 9), Osteomodulin, and COL1A1 (Collagen 1A1), respectively. The oncogenic mechanism in these fusion genes is akin to CDH11-USP6, with the USP6 coding sequences juxtaposed to the promoter regions in each of the four novel translocation partners. The novel fusion partners appear well suited to drive USP6 transcription in the bone/mesenchymal context: osteomodulin is expressed strongly in osteoblastic lineages, and the COL1A1 promoter has an oncogenic role in the mesenchymal cancer dermatofibrosarcoma protuberans. In summary, these studies show that USP6 oncogenic activation results from heterogeneous genomic mechanisms involving USP6 transcriptional upregulation by juxtaposition with ectopic promoters.

Cytogenetic and molecular cytogenetic findings in 43 aneurysmal bone cysts: aberrations of 17p mapped to 17p13.2 by fluorescence in situ hybridization.

Aneurysmal bone cyst is a benign, cystic lesion of bone composed of blood-filled spaces separated by fibrous septa. Relatively few cases of aneurysmal bone cyst have been cytogenetically characterized, yet abnormalities of the short arm of chromosome 17 appear to be recurrent. In this study, conventional cytogenetic analysis of 43 aneurysmal bone cyst specimens from 38 patients over a 12-year period revealed clonal chromosomal abnormalities in 12 specimens. Karyotypic anomalies of 17p, including a complex translocation and inversion, were identified in eight of these 12 specimens. In an effort to further define the aberrant 17p breakpoint, fluorescence in situ hybridization (FISH) analyses were performed using a series of probe combinations spanning a 5.1 Mb region between the TP53 (17p13.1) and Miller-Dieker lissencephaly syndrome (17p13.3) gene loci. These studies revealed the critical breakpoint locus at 17p13.2, flanked proximally by an RP11-46I8, RP11-333E1, and RP11-457I18 bacterial artificial chromosome (BAC) probe cocktail and distally by an RP11-198F11 and RP11-115H24 BAC and RP5-1050D4 P1 artificial chromosome (PAC) probe cocktail. Overall, abnormalities of the 17p13.2 locus were identified by metaphase and/or interphase cell FISH analysis in 22 of 35 (63%) aneurysmal bone cyst specimens examined including 26 karyotypically normal specimens. These cytogenetic and molecular cytogenetic findings expand our knowledge of chromosomal alterations in aneurysmal bone cyst, further localize the critically involved 17p breakpoint, and provide an alternative approach (ie FISH) for detecting 17p abnormalities in nondividing cells of aneurysmal bone cysts. The latter could potentially be utilized as an adjunct in diagnostically challenging cases.

Translocation (2;11)(q31;q12) is recurrent in collagenous fibroma (desmoplastic fibroblastoma).

Collagenous fibroma (desmoplastic fibroblastoma) is a rare, benign tumor composed of spindle and stellate-shaped fibroblasts and myofibroblasts in a densely collagenous background. A t(2;11)(q31;q12) has been reported in one case of collagenous fibroma and a rearrangement of the 11q12 breakpoint in a second case. In the present study, we detected a t(2;11) identical to that previously described in a collagenous fibroma arising in the supraclavicular fossa of a 55-year-old man. This finding confirms the nonrandom association of t(2;11)(q31;q12) with collagenous fibroma.

Ewing sarcoma/primitive neuroectodermal tumor of the chest wall: impact of initial versus delayed resection on tumor margins, survival, and use of radiation therapy.

OBJECTIVE: To establish outcome and optimal timing of local control for patients with nonmetastatic Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) of the chest wall. METHODS: Patients < or =30 years of age with ES/PNET of the chest wall were entered in 2 consecutive protocols. Therapy included multiagent chemotherapy; local control was achieved by resection, radiotherapy, or both. We compared completeness of resection and disease-free survival in patients undergoing initial surgical resection versus those treated with neoadjuvant chemotherapy followed by resection, radiotherapy, or both. Patients with a positive surgical margin received radiotherapy. RESULTS: Ninety-eight (11.3%) of 869 patients had primary tumors of the chest wall. Median follow-up was 3.47 years and 5-year event-free survival was 56% for the chest wall lesions. Ten of 20 (50%) initial resections resulted in negative margins compared with 41 of 53 (77%) negative margins with delayed resections after chemotherapy (P = 0.043). Event-free survival did not differ by timing of surgery (P = 0.69) or type of local control (P = 0.17). Initial chemotherapy decreased the percentage of patients needing radiation therapy. Seventeen of 24 patients (70.8%) with initial surgery received radiotherapy compared with 34 of 71 patients (47.9%) who started with chemotherapy (P = 0.061). If a delayed operation was performed, excluding those patients who received only radiotherapy for local control, only 25 of 62 patients needed radiotherapy (40.3%; P = 0.016). CONCLUSION: The likelihood of complete tumor resection with a negative microscopic margin and consequent avoidance of external beam radiation and its potential complications is increased with neoadjuvant chemotherapy and delayed resection of chest wall ES/PNET.

Inconspicuous insertion 22;12 in myxoid/round cell liposarcoma accompanied by the secondary structural abnormality der(16)t(1;16).

In myxoid/round cell liposarcoma, the t(12;16)(q13;p11) and its associated fusion transcript, FUS-CHOP, characterize greater than 95% of cases. The variant translocation t(12;22)(q13;q12) and associated EWS-CHOP fusion transcript are rare. A second non-random aberration observed in roughly 20% of Ewing's sarcomas, and to a lesser extent other select sarcomas, is the unbalanced 1;16 translocation. Recognition of this secondary aberration in the absence of an obvious primary karyotypic abnormality strongly suggests that the use of other genetic approaches will be informative in uncovering a clinically suspected primary anomaly. The following case illustrates the utility of molecular cytogenetic and reverse transcriptase-polymerase chain reaction techniques in diagnosing an ins(22;12)(q12;q13q14) and associated EWS-CHOP fusion transcript in a myxoid/round cell liposarcoma exhibiting a der(16)t(1;16)(q11;q11).

Translocation (1;4)(p31;q34) in nonossifying fibroma.

Nonossifying fibroma is a benign, lytic lesion of fibrous origin most often observed in the metaphyseal region of the long bones in children and adolescents. It is frequently asymptomatic and is often characterized by a history of spontaneous resolution. Herein, we report a clinicohistopathologically typical case of nonossifying fibroma arising in the tibia of an 18-year-old skeletally mature female. Conventional cytogenetic analysis revealed a reciprocal translocation involving bands 1p31 and 4q34 [t(1;4)(p31;q34)]. To the best of our knowledge, this is only the second reported case of a clonally aberrant nonossifying fibroma.

Chromosome 6 abnormalities are recurrent in synovial chondromatosis.

Synovial chondromatosis, a lesion composed of multiple nodules of cartilage involving articular or tendon sheath synovial membranes, has traditionally been considered a metaplastic condition. A specific or characteristic chromosomal anomaly has not yet been identified in synovial chondromatosis. Cytogenetic and molecular cytogenetic analyses of three cases of synovial chondromatosis revealed clonal karyotypic abnormalities in all three cases including structural abnormalities of chromosome 6 in two. Anomalies of chromosome 6 have been observed in three of five previously reported synovial chondromatosis cases. These findings support a neoplastic origin for synovial chondromatosis and suggest that chromosome 6 aberrations are recurrent in this lesion.

Cytogenetic and molecular cytogenetic evidence of recurrent 8q24.1 loss in osteochondroma.

Osteochondroma most frequently arises sporadically and as a solitary lesion, but may also arise as multiple lesions characterizing the autosomal dominant disorder hereditary multiple exostoses (HME) and the contiguous gene-deletion syndrome, Langer-Giedion syndrome (LGS). Various germline mutations of two putative tumor suppressor genes, EXT1 localized to 8q24.1 and EXT2 localized to 11p11 approximately p12, have been demonstrated in HME families. Constitutional chromosomal deletions or structural rearrangements of 8q24.1 are seen in LGS. Cytogenetic reports of sporadic and hereditary osteochondromas are few, but have revealed loss or structural rearrangements of 8q24.1 in a small number of tumors. In the current study, karyotypic evaluation of 37 osteochondroma specimens (both sporadic and hereditary lesions) revealed chromosomal anomalies of 8q24.1 in 10 specimens (27%). In an effort to determine the presence and frequency of submicroscopic deletions, molecular cytogenetic studies were performed on this same set of tumors utilizing a chromosome 8 specific centromeric probe and an 8q24.1 cosmid probe (locus D8S51, within the minimal LGS deletion region). Loss of the 8q24.1 locus was detected by fluorescence in situ hybridization in 27 of 34 (79%) osteochondroma specimens analyzed including all 10 specimens exhibiting chromosome 8 abnormalities cytogenetically. These findings indicate that a significant subset of osteochondromas harbor genetic aberrations at the EXT1 locus and suggest that loss or mutation of EXT1 plays an important role in the pathogenesis of sporadic as well as hereditary osteochondromas.

Delayed diagnosis of osseous blastomycosis in two patients following environmental exposure in nonendemic areas.

Blastomycosis generally results from inhalation of Blastomyces dermatitidis conidia following exposure to contaminated soil in an endemic area. Primary infections commonly involve the lungs, although secondary dissemination to other body sites may occur. We describe 2 cases of osseous blastomycosis in people living outside the endemic areas. Both patients reported exposure to soilfollowing injury to the knee from occupational activities. Mold isolated from each case was identified as B dermatitidis by micromorphologic characteristics including yeast conversion testing and by a positive AccuProbe Blastomyces dermatitidis test (GenProbe, San Diego, CA). Retrospective review of histologic slides, initially reported as negative, identified rare poorly staining, broad-based budding yeast forms in each case. Both patients were treated successfully with itraconazole with no evidence of recurrent infection after 1 year These cases illustrate the importance of considering blastomycosis in the differential diagnosis of bony lesions, even though the patient may live outside an endemic area for B dermatitidis.

Translocation der(13;21)(q10;q10) in skeletal and extraskeletal mesenchymal chondrosarcoma.

Cytogenetic studies of mesenchymal chondrosarcoma are few and to date, no specific or recurrent aberrations have been found. In this investigation, the cytogenetic and molecular cytogenetic (spectral karyotypic and fluorescence in situ hybridization) findings for two mesenchymal chondrosarcomas, one arising skeletally and the other extraskeletally, are reported. An identical Robertsonian translocation involving chromosomes 13 and 21 [der(13;21)(q10;q10)] was detected in both cases, possibly representing a characteristic rearrangement for this histopathologic entity. Both cases also exhibited loss of all or a portion of chromosomes 8 and 20 and gain of all or a portion of chromosome 12. The observation of similar chromosomal abnormalities in both skeletal and extraskeletal mesenchymal chondrosarcoma supports a genetic as well as histopathologic relationship between these anatomically distinct neoplasms.

Impact of SYT-SSX fusion type on the clinical behavior of synovial sarcoma: a multi-institutional retrospective study of 243 patients.

Synovial sarcomas are aggressive spindle cell sarcomas containing in some cases areas of epithelial differentiation. They consistently show a specific t(X;18;p11;q11), which usually represents either of two gene fusions, SYT-SSX1 or SYT-SSX2, encoding putative transcriptional proteins differing at 13 amino acid positions. Previous studies have suggested that patients with SYT-SSX2 tumors do better than those with SYT-SSX1 tumors, but the study groups were too limited to be conclusive. To address this issue more definitively, we collected data on SYT-SSX fusion type, pathology, and clinical course in a retrospective multi-institutional study of 243 patients (age range, 6-82) with synovial sarcoma. SYT-SSX1 and SYT-SSX2 fusions were detected in 147 tumors (61%) and 91 tumors (37%), respectively. Histologically, 61 (25%) were classified as biphasic type and 180 (74%) as monophasic type based on the presence or absence of areas of glandular epithelial differentiation, respectively. Median and 5-year overall survivals for the SYT-SSX1 and SYT-SSX2 groups were 6.1 years and 53%, and 13.7 years and 73%, respectively. Overall survival was significantly better among SYT-SSX2 cases (P = 0.03), among cases localized at diagnosis (P < 0.0001), and among patients with primary tumors < 5 cm in greatest dimension (P = 0.01). Age, sex, histological type, and axial versus peripheral primary site had no impact on overall survival. The impact of fusion type on survival remained significant when stratified for primary tumor size (P = 0.03) but was no longer significant when stratified for disease status at presentation. This may reflect the tendency for patients with SYT-SSX1 tumors to present more often with metastatic disease (P = 0.05). Cox regression identified disease status (P < 0.0001) and primary tumor size (P = 0.04) as the only factors independently predictive of overall survival in the subset of 160 patients with information on all of the factors. Within the subset of patients with localized disease at diagnosis (n = 202), the median and 5-year survival for the SYT-SSX1 and the SYT-SSX2 groups were 9.2 years and 61% versus 13.7 years and 77%, respectively. Patients whose tumors contained the SYT-SSX2 fusion (P = 0.08) or were smaller (P = 0.12) showed a trend toward better survival by log-rank test, whereas tumor histology had no impact (P = 0.8). In a Cox regression analysis considering all of the factors, SYT-SSX fusion type emerged as the only independent significant factor (P = 0.04) for overall survival within the subset of 133 patients with localized disease at diagnosis who had information on all of the factors. Among other comparisons, there was a strong association of fusion type and morphology (P < 0.001), with almost all of the SYT-SSX2 tumors showing absence of glandular differentiation (monophasic histology) and almost all of the biphasic tumors containing SYT-SSX1. There was also a statistically significant association of fusion type and patient sex (P = 0.03); specifically, the male:female ratio of SYT-SSX1 cases was 1:1, whereas for SYT-SSX2 cases, it was close to 1:2. Overall, SYT-SSX fusion type appears to be the single most significant prognostic factor by multivariate analysis in patients with localized disease at diagnosis. SYT-SSX fusion type also appears to exert part of its impact on prognosis before presentation through its association with stage at diagnosis. In addition, the associations of SYT-SSX fusion type with patient sex and tumor epithelial differentiation point to interesting mechanistic biological differences.