The utility of FISH analysis in the diagnosis of BCOR-rearranged sarcomas.

BACKGROUND: A BCL6 corepressor (BCOR) gene alteration is a genetic signature of rare subsets of sarcomas. The identification of this alteration has recently contributed to the definition of new entities in the current WHO (2020) classification of soft tissue and bone tumours. We retrospectively examined cases of BCOR-rearranged sarcoma (BRS) to assess the reliability of the BCOR FISH analysis using an IVD (in vitro diagnostic) probe. METHODS: We investigated and compared the molecular diagnostic strategies and features by collecting 17 data from patients with a BCOR gene rearrangement detected using quantitative-Reverse Transcription-Polymerase Chain Reaction (qRTPCR), Next-Generation Sequencing (NGS) and Fluorescence in situ hybridization (FISH). RESULTS: We describe fourteen BCOR::CCNB3 sarcomas, one spindle cell sarcoma with a novel BCOR::MAML1 fusion, one spindle cell sarcoma with a novel BCOR::AHR fusion, and one ossifying fibromyxoid tumour with a BCOR::ZC3H7B fusion. FISH analysis of all, except one, BCOR::CCNB3 sarcoma, showed a FISH break-apart pattern with mild signal separation. The MAML1::BCOR sarcoma showed large-space split signals, while in the two patients with AHR::BCOR and ZC3H7B::BCOR fusions, no BCOR rearrangement was observed using FISH. CONCLUSIONS: Our study indicates that BCOR FISH analysis using an IVD probe, may be useful to detect the presence of a BCOR rearrangement, including both translocations and inversions; however, negative results, in some cases, can occur.

SMARCB1/INI1 loss in skull base conventional chordomas: a clinicopathological and molecular analysis.

Introduction: The loss of SMARCB1/INI1 protein has been recently described in poorly differentiated chordoma, an aggressive and rare disease variant typically arising from the skull base. Methods: Retrospective study aimed at 1) examining the differential immunohistochemical expression of SMARCB1/INI1 in conventional skull base chordomas, including the chondroid subtype; 2) evaluating SMARCB1 gene deletions/copy number gain; and 3) analyzing the association of SMARCB1/INI1 expression with clinicopathological parameters and patient survival. Results: 65 patients (35 men and 30 women) affected by conventional skull base chordoma, 15 with chondroid subtype, followed for >48 months after surgery were collected. Median age at surgery was 50 years old (range 9-79). Mean tumor size was 3.6 cm (range 2-9.5). At immunohistochemical evaluation, a partial loss of SMARCB1/INI1 (>10% of neoplastic examined cells) was observed in 21 (32.3%) cases; the remaining 43 showed a strong nuclear expression. Fluorescence in situ hybridization (FISH) analysis was performed in 15/21 (71.4%) cases of the chordomas with partial SMARCB1/INI1 loss of expression. Heterozygous deletion of SMARCB1 was identified in 9/15 (60%) cases and was associated to copy number gain in one case; no deletion was found in the other 6 (40%) cases, 3 of which presenting with a copy number gain. No correlations were found between partial loss of SMARCB1/INI1 and the clinicopathological parameters evaluated (i.e., age, tumor size, gender, tumor size and histotype). Overall 5-year survival and 5-year disease-free rates were 82% and 59%, respectively. According to log-rank test analysis the various clinico-pathological parameters and SMARCB1/INI1 expression did not impact on overall and disease free-survival. Discussion: Partial loss of SMARCB1/INI1, secondary to heterozygous deletion and/or copy number gain of SMARCB1, is not peculiar of aggressive forms, but can be identified by immunohistochemistry in a significant portion of conventional skull base chordomas, including the chondroid subtype. The variable protein expression does not appear to correlate with clinicopathological parameters, nor survival outcomes, but still, it could have therapeutic implications.

A global collaboRAtive study of CIC-rearranged, BCOR::CCNB3-rearranged and other ultra-rare unclassified undifferentiated small round cell sarcomas (GRACefUl).

BACKGROUND: Undifferentiated small round cell sarcomas (URCSs) represent a diagnostic challenge, and their optimal treatment is unknown. We aimed to define the clinical characteristics, treatment, and outcome of URCS patients. METHODS: URCS patients treated from 1983 to 2019 at 21 worldwide sarcoma reference centres were retrospectively identified. Based on molecular assessment, cases were classified as follows: (1) CIC-rearranged round cell sarcomas, (2) BCOR::CCNB3-rearranged round cell sarcomas, (3) unclassified URCSs. Treatment, prognostic factors and outcome were reviewed. RESULTS: In total, 148 patients were identified [88/148 (60%) CIC-rearranged sarcoma (median age 32 years, range 7-78), 33/148 (22%) BCOR::CCNB3-rearranged (median age 17 years, range 5-91), and 27/148 (18%) unclassified URCSs (median age 37 years, range 4-70)]. One hundred-one (68.2%) cases presented with localised disease; 47 (31.8%) had metastases at diagnosis. Male prevalence, younger age, bone primary site, and a low rate of synchronous metastases were observed in BCOR::CCNB3-rearranged cases. Local treatment was surgery in 67/148 (45%) patients, and surgery + radiotherapy in 52/148 (35%). Chemotherapy was given to 122/148 (82%) patients. At a 42.7-month median follow-up, the 3-year overall survival (OS) was 92.2% (95% CI 71.5-98.0) in BCOR::CCNB3 patients, 39.6% (95% CI 27.7-51.3) in CIC-rearranged sarcomas, and 78.7% in unclassified URCSs (95% CI 56.1-90.6; p < 0.0001). CONCLUSIONS: This study is the largest conducted in URCS and confirms major differences in outcomes between URCS subtypes. A full molecular assessment should be undertaken when a diagnosis of URCS is suspected. Prospective studies are needed to better define the optimal treatment strategy in each URCS subtype.

Osteogenic sarcomas of the hands: A case series with emphasis in its peculiarities and literature review.

AIM: To present our experience on osteosarcomas of the hands and review the existing literature pertaining osteosarcomas in this extremely rare location. METHODS: and results: Seven cases of osteosarcomas of the hands were reviewed, and a literature search of all primary osteosarcomas of the hands was performed. All tumors occurred in adults (mean age, 41 years) and were located mainly around the metacarpophalangeal joints. All patients presented with localized long-lasting pain as main symptom. The mean size at diagnosis was 33 mm. Three tumors were low-grade central osteosarcomas, 1 low-grade central chondroblastoma-like osteosarcoma and 3 high-grade osteosarcomas. All tumors were positive for mouse double-minute 2 homolog (MDM2) immunohistochemistry. Three cases yielded results with fluorescence in-situ amplification for MDM2 (12q15)/CEP12. At last follow-up, one patient with a high-grade osteosarcoma was dead of disease. The literature review revealed similar demographic and site distribution of osteosarcomas within the hands than our series and an unusually high proportion of low-grade central and parosteal osteosarcomas when compared to the proportion of these infrequent neoplasms in the whole skeleton. CONCLUSIONS: osteosarcomas of hands present in older individuals compared to the population affected by conventional osteosarcomas of all sites. Importantly from a diagnostic, therapeutic and prognostic points of view, around 40% of osteosarcomas of the hands are low-grade osteosarcomas of the central or parosteal types.

Periosteal chondrosarcoma: A case series in a referral center with survivorship analysis.

BACKGROUND: Periosteal chondrosarcomas are among the rarest types of chondrosarcomas dealt with in few small series of cases. In this study, we aimed to present our experience with this chondrosarcoma, seek for prognostic factors for OS and DFS and survey the status of IDH1 and IDH2. RESULTS: 55 periosteal chondrosarcomas were retrospectively identified. Median age was 37 years, there was a male predominance (62%). The great majority of cases involved the metaphysis of long bones of the extremities. The median size of the tumors was 7.5 cm. Thirty patients underwent to subtotal surgical resection, 22 to tangential resection and the remaining 3 to amputation. The margins, reported in 54 cases, were wide/radical in 38 patients (70.4%), marginal in 9 (16.7%) and intralesional in 7 (12.9%). Histologically, 23 (42%) were grade 1; 27 (49%), grade 2; 3 (5%), grade 3 and 2 (4%) were dedifferentiated. A third of cases in which mutational analysis was feasible harbored heterozygous mutations in codon 132 of IDH1. Fifty-four cases were included for follow-up (median, 137 months). Four patients had local recurrences and six patients developed metastasis to the lungs. All patients that developed metastasis died of disease, two died of unrelated causes and 46 were alive without disease. OS and DFS was not found to be statistically associated with clinical and pathological parameters considered. CONCLUSIONS: periosteal chondrosarcomas exhibit a low-grade behavior that can be adequately treated with marginal excisions. Clinical and morphologic parameters do not seem to predict their outcome.

Primary malignant peripheral nerve sheath tumors of bone: a clinicopathologic reappraisal of 8 cases.

Primary spindle cell and pleomorphic sarcomas of bone represent an exceedingly rare group of mesenchymal malignancies that include soft tissue histotypes, as malignant peripheral nerve sheath tumor. Outside the head and neck region, only 36 cases of primary malignant peripheral nerve sheath tumor of bone have been described. We retrieved from our archives eight cases of primary malignant peripheral nerve sheath tumor of bone arising outside the head and neck region, describing their clinical, radiological, and morphologic features. Our series, in which all but one patient died of diseases after a median of seven months, confirms that primary malignant peripheral nerve sheath tumors of bone are aggressive tumors. Pathologists should be aware of this rare histotype. More aggressive and active adjuvant treatments should be investigated.

Secondary peripheral chondrosarcoma arising in solitary osteochondroma: variables influencing prognosis and survival.

BACKGROUND: Secondary peripheral chondrosarcomas arising in solitary osteochondromas is an unusual complication, reported in small series. In this study, we aimed to present our experience with this rare variant of chondrosarcoma and compare results with already published data in order to determine prognostic factors for overall and disease-free survival. METHODS: The case study includes retrospective data from patients diagnosed at a single institution from 1943 to 2019. Clinical data were collected reviewing all available medical records from first to last follow-up visits. To exclude the presence of the Multiple Osteochondroma Hereditary Syndrome, few patients, with a suspect of a familial form of the disease, were evaluated for the presence of germline heterozygous variants in EXT1 and EXT2 genes. Results were summarized using descriptive statistics and statistical analysis were performed to reveal associations between variables. RESULTS: Two hundred and fourteen secondary peripheral chondrosarcomas that arose exclusively from solitary osteochondromas diagnosed in a multidisciplinary setting at the IRCCS Istituto Ortopedico Rizzoli were retrospectively identified, 66.4% males and 33.6% females with a median age at diagnosis of 38 years. The local recurrence rate was 17.3%, while the metastases one was 5.1%. Besides age, a high histologic grade is the only factor associated with worse 5-year and 10-year overall survival (log-rank p = 0.0005, HR = 3.74; 95% CI 1.69-8.26). Moreover, high histological grade (HR = 3.75; 95% CI = 1.69-8.34; p = 0.001) and surgical debulking (HR = 3.71; 95% CI = 1.57-8.79; p = 0.003) were associated with a significantly worse disease-free survival. CONCLUSIONS: Our study confirm the low-grade behavior of secondary peripheral chondrosarcomas and demonstrate that the best choice of treatment for those arising in solitary osteochondromas is the wide surgical excision, when possible. Location per se is not a factor that affects prognosis, while the accurate histological grade assessment is correlated with the tumor aggressiveness and a long term follow up is necessary for this rare variant of chondrosarcoma.

CIC rearranged sarcomas: A single institution experience of the potential pitfalls in interpreting CIC FISH results.

AIM: The aim of this study was to establish how reliable FISH CIC analysis using an IVD (in vitro diagnostic) commercial probe is. METHODS AND RESULTS: A series of 19 CIC-DUX4 sarcomas were evaluated. The samples presenting CIC-DUX4 fusion transcript detected by Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Sanger sequencing and/or Next Generation Sequencing were selected for Fluorescent in Situ Hybridization (FISH) CIC analysis with CIC break-apart IVD probe and compared to molecular analysis. CIC FISH analysis showed 26% of false negatives. CONCLUSION: Our results indicate that, in the setting of CIC-DUX4 fusion positive small round cell sarcomas, CIC FISH using IVD commercial probe may lead to false-negative results. This novel study evaluates the diagnostic use of a commercial IVD CIC probe for FISH.

The Efficacy of Molecular Analysis in the Diagnosis of Bone and Soft Tissue Sarcoma: A 15-Year Mono-Institutional Study.

The histological diagnosis of sarcoma can be difficult as it sometimes requires the combination of morphological and immunophenotypic analyses with molecular tests. A total of 2705 tissue samples of sarcoma consecutively collected from 2006 until 2020 that had undergone molecular analysis were assessed to evaluate their diagnostic utility compared with histological assessments. A total of 3051 molecular analyses were performed, including 1484 gene fusions tested by c/qRT-PCR, 992 gene rearrangements analysed by FISH, 433 analyses of the gene status of MDM2, 126 mutational analyses and 16 NGS analysis. Of the samples analysed, 68% were from formalin-fixed, paraffin-embedded tissue and 32% were from frozen tissue. C/qRT-PCR and FISH analyses were conclusive on formalin-fixed, paraffin-embedded tissue in 74% and 76% of samples, respectively, but the combination of the two methods gave us conclusive results in 96% and 89% of frozen and formalin-fixed, paraffin-embedded tissues, respectively. We demonstrate the utility of c/qRT-PCR and FISH for sarcoma diagnosis and that each has advantages in specific contexts. We conclude that it is possible to accurately predict the sarcoma subtype using a panel of different subtype-specific FISH probes and c/qRT-PCR assays, thereby greatly facilitating the differential diagnosis of these tumours.

Primary synovial sarcoma of bone: a retrospective analysis of 25 patients.

AIMS: To evaluate the diagnostic accuracy of SSX and SSX::SS18 antibodies in decalcified surgical specimens and outcome of synovial sarcomas (SS) of bone. METHODS AND RESULTS: Twenty-five cases were classified as bone SS (prevalence 0.32% among malignant primary bone sarcoma). Median age was 34 years (range = 9-79). Twenty-four of 25 patients presented with non-metastatic tumours, one with lung metastases. The majority of tumours involved the long bones of extremities with metaphyseal origin. Mean size of the tumour was 7.1 cm. Twenty cases (80%) were monophasic and five (20%) were biphasic. SS18::SSX fusion-specific antibody had 92% sensitivity and 99% specificity for primary bone SS, whereas SSX C-terminus antibody had 100% sensitivity and 94% specificity. Fluorescence in-situ hybridisation (FISH) analysis was feasible in nine (36%) cases and detected SS18 rearrangement in all nine cases. All patients underwent surgical removal of their primary tumour, with adequate margins in 18 (72%) patients. Chemotherapy with metothrexate, cisplatin, doxorubicin and ifosfamide was used in the seven patients. Two patients with inadequate surgical margins received radiotherapy. With a median follow-up of 80 months (range = 6-428), 5- and 10-year overall survival (OS) was 66.6% and 47.9%, respectively, and 5 and 10 years' disease-free survival (DFS) was 36.8% [95% confidence interval (CI) = 18.0-55.7%] and 32.2% (95% CI = 14.6-51.2%), respectively. A significant improvement in 10 years' DFS in patients undergoing chemotherapy compared with patients who did not was observed (P = 0.039). CONCLUSIONS: Our series highlights the utility of SS18::SSX fusion-specific and SSX C-terminus antibodies to support the diagnosis of SS. Adjustment chemotherapy was associated with improved prognosis in this series.

Identification of a novel fusion transcript EWSR1-VEZF1 by anchored multiplex PCR in malignant peripheral nerve sheath tumor.

The aim of the study is to describe a novel genetic finding examining the molecular and pathological features of a case of malignant peripheral nerve sheath tumor occurring in the thigh of a 17-year-old male. Fusion gene detection using a next-generation sequencing-based anchored multiplex PCR technique (Archer FusionPlex Sarcoma Panel) was used to identify the novel fusion of EWSR1-VEZF1 from the frozen tumor sample. EWSR1-VEZF1 fusion is a novel molecular gene rearrangement involving exon 8 of the EWSR1 gene and exon 2 of the VEZF1 gene. Data were validated with gene sequencing and fluorescent in situ hybridization (FISH) analysis. This case report describes a novel rearrangement involving EWSR1 on chromosome 22 and VEZF1 on chromosome 17. The result obtained demonstrates the value of the next-generation sequencing-based anchored multiplex PCR technique (Archer FusionPlex Sarcoma Panel) both in diagnosis and patient care and might become a helpful diagnostic tool for this tumor type.

Randomized, Placebo-controlled Study of a Nutraceutical Based on Hyaluronic Acid, L-carnosine, and Methylsulfonylmethane in Facial Skin Aesthetics and Well-being.

Objective: The purpose of this study was to evaluate the efficacy and safety of a multicomponent nutraceutical (MCN) on facial skin. Methods: A randomized, placebo-controlled, single-blind trial was conducted involving two groups of female subjects affected by facial skin photoaging. For two months, volunteers took a daily dose of MCN containing 200mg of hyaluronic acid, 500mg of L-carnosine, and 400mg of methylsulfonylmethane, or a placebo. At Day 0 (T0) and Day 60 (T60), face skin hydration, elasticity, and sebometry were measured with an instrumental skin tester, and digital images of facial wrinkles were scored. A subject-based quali-/ quantitative assessment evaluating satisfaction/ quality of life was performed at T60. Results: The MCN and placebo groups each included 25 volunteers (mean ages: 49.3 and 47.8 years, respectively). After 60 days of MCN intake, glabella skin hydration and elasticity improved by 15.2 percent and 22.6 percent, respectively (p=0.03; p=0.004), glabella sebaceous secretion decreased by 24.2 percent (p=0.01), skin hydration and elasticity of the periocular area increased by 12.6 percent and 15.9 percent, respectively, and skin hydration and elasticity of the oral commissural area increased by 17.6 percent and 16 percent, respectively (p<0.001). No significant variation occurred in the placebo group. Wrinkle depth improved slightly in the MCN group (p=0.043 in the periocular area) but not in the placebo group. A slight improvement in joint pain and mucosae/ hair appearance was reported in the questionnaire in the MCN group only. Conclusions: Our results suggest that MCN is safe and effective for facial skin aesthetics and well-being.

Detection of circulating tumor cells in liquid biopsy from Ewing sarcoma patients.

BACKGROUND: Circulating tumor cells (CTCs) analysis is a promising new diagnostic field to estimate risk and monitor treatment efficacy, metastatic relapse, and progression in cancer patients. The study aim was to isolate and characterize CTCs in blood samples of Ewing sarcoma (ES) patients exploiting two main characteristics: CD99 expression and presence of chromosomal translocations. MATERIALS AND METHODS: The method isolated CTCs from peripheral blood (PB) of ES patients. Cell-surface CD99 was a useful marker for CTCs determined using immunomagnetic separation with microbeads and CD99 monoclonal antibody. We tested sensitivity and specificity by detecting CTCs in blood collected from healthy donors and randomly during therapy from 18 ES patients. Evidence of CTCs was confirmed by detection of specific molecular markers using quantitative and digital reverse transcription-polymerase chain reaction targeting EWSR1/FLI1 type 1 and type 2 or EWSR1/ETS-related gene transcripts type 1 and type 9e. RESULTS: Feasibility of finding CTCs in PB of ES patients by immunoseparation with CD99 antibody and magnetic microbeads was demonstrated for the first time. At molecular analysis, three PB specimens tested positive for chimeric EWSR1/FLI1 type 2 and one PB for chimeric EWSR1/FLI1 type 2. CTCs detection was found above a limit of detection of 1 cell/mL of PB. CONCLUSION: CTCs in PB of ES patients can be identified by this method and in ES CTCs analysis can be used as a liquid biopsy approach for prognostic and predictive purposes. The potential clinical implications of CTCs in PB samples detected by the platform for CTC isolation with molecular confirmation during therapy require further evaluation.

Detection of H3F3A p.G35W and p.G35R in giant cell tumor of bone by Allele Specific Locked Nucleic Acid quantitative PCR (ASLNAqPCR).

Giant Cell Tumor (GCT) represents about 20% of benign bone tumors, is locally aggressive although malignant transformation is extremely rare, <1% of cases but 2-3% give pulmonary metastasis. Age at onset is between 20 and 40 years with a slight predominance for the female gender. GCT is characterized by specific mutations in H3F3A gene encoding the protein histone 3.3. The study of these mutations is important for the differential diagnosis with giant cell rich sarcomas, chondroblastoma and aneurysmal bone cyst. To identify the most frequent H3F3A mutations we developed a novel allele specific Real Time Polymerase Chain Reaction method, based on Allele Specific Locked Nucleic Acid (ASLNAqPCR) that is here described. Molecular analyses were performed on 20 GCT and 2 osteosarcoma arising on a previous GCT. All cases were verified by Sanger sequencing. We demonstrated that ASLNAqPCR is a quick, sensitive and reliable method to identify mutations of the H3F3A gene, in giant cell tumor of bone, to support diagnosis in morphologically ambiguous cases.

Fibrocartilaginous mesenchymoma of bone: a single-institution experience with molecular investigations and a review of the literature.

AIMS: Fibrocartilaginous mesenchymoma is a rare intraosseous lesion, with a total of 26 cases described in the literature. This study describes the clinical, radiological and histological features of eight new cases of fibrocartilaginous mesenchymoma collected at a single institution between 1982 and 2016. The presence of GNAS and IDH1/2 mutations and MDM2 amplification was explored to evaluate possible links between fibrocartilaginous mesenchymoma, fibrous dysplasia, de-differentiated chondrosarcoma and low-grade osteosarcoma. METHODS AND RESULTS: Eight new cases of fibrocartilaginous mesenchymoma of bone identified in our archives, dating from 1982 to 2016, were reviewed. The diagnosis was not performed on the initial biopsy in any of these cases, due mainly to the absence of obvious cartilaginous differentiation. On imaging, the tumour contained cartilaginous calcifications and showed a very strong uptake of contrast medium after injection. Histologically, the tumour was characterized by spindle cell proliferation mimicking a low-grade spindle cell sarcoma, associated with epiphyseal growth-plate-like nodules of cartilage and bone production. Molecularly, no GNAS and IDH1/2 mutations or MDM2 amplification were found in the cases analysed. Only one case recurred 1 year following intralesional resection. None died of disease. CONCLUSIONS: This very rare bone tumour has a typical radiological and histological pattern and a favourable survival outcome after treatment. Local recurrences can be prevented with complete surgery. Fibrocartilaginous mesenchymoma does not seem to be related genetically to fibrous dysplasia, low-grade osteosarcoma and de-differentiated chondrosarcoma.

Recurrence After Marginal Excision for Atypical Lipomatous Tumors Versus Lipomas of the Extremities.

This study reviewed the medical records of 90 patients with lipomas (47 patients) and atypical lipomatous tumors (ALT)/well-differentiated liposarcomas (WDL) (43 patients) of the extremities treated from 2006 to 2012. All patients had preoperative biopsy and postoperative histologic analysis of the tumors; surgical margins were marginal in all cases. Histologic sections of the tissue blocks from the excised specimens were re-reviewed for all patients; a consensus with postoperative histologic analysis was confirmed. Molecular chromosome analysis was performed on fluorescence in situ hybridization in tissue sections from the tissue blocks in all cases for the purpose of this study; a ratio greater than 2 was considered to represent murine double-minute 2 (MDM2) amplification consistent with a diagnosis of ALT/WDL. Mean follow-up was 52 months (range, 14-96 months). Local recurrence and metastasis rates and the relationship of patient age and sex with tumor size and location were evaluated. None of the patients with lipomas experienced local recurrence compared with 6 patients (13.9%) with ALT/WDL who experienced local recurrence within a mean of 48 months (range, 33-96 months); this difference was statistically significant. None of the patients in either group experienced metastasis prior to the study period. Local recurrence did not correlate statistically with patient age or sex, or with tumor size or location. [Orthopedics. 2016; 39(4):e610-e614.].

CIC-DUX4 fusion-positive round-cell sarcomas of soft tissue and bone: a single-institution morphological and molecular analysis of seven cases.

AIMS: Round-cell sarcomas lacking specific translocations represent a diagnostic challenge. The aim of this study was to describe seven cases of CIC-DUX4 fusion-positive sarcomas, including the first reported example arising primarily in bone. METHODS AND RESULTS: Patients ranged in age from 15 years to 44 years (median: 33 years). Six cases arose from the soft tissues, and one from the iliac bone. Morphologically, all cases showed an undifferentiated round-cell population with greater atypia and pleomorphism than Ewing sarcoma. Immunohistochemically, all tumours showed focal and weak positivity for CD99, and five of seven showed nuclear and/or cytoplasmic positivity for Wilms tumour 1. Five patients had lung metastases at presentation. All patients received chemotherapy according to Ewing sarcoma protocols. All but one patient (the one with a bone tumour) died of disease after a mean of 14.5 months from the diagnosis (range: 8-20 months). CONCLUSIONS: Our series confirms that CIC-DUX4 fusion-positive sarcomas are aggressive tumours with an adverse prognosis, and with clinical, histological and genetic differences from Ewing sarcoma. The best therapeutic approach needs to be investigated.

Small cell osteosarcoma: clinicopathologic, immunohistochemical, and molecular analysis of 36 cases.

Small round cell osteosarcoma is a very rare type of osteosarcoma, histologically mimicking other small round cell malignancies of bone, most notably Ewing sarcoma. To distinguish small cell osteosarcoma from other primary small cell malignancies of bone, we evaluated the immunohistochemical (IHC) expression of CD99 and SATB2, a marker of osteoblastic differentiation. Second, we analyzed EWSR1 and FUS gene aberrations using fluorescence in situ hybridization and/or reverse transcription-polymerase chain reaction (RT-PCR) techniques to assess whether small cell osteosarcoma and Ewing sarcoma share the same genetic alteration analysis. Thirty-six cases of primitive small cell osteosarcoma of bone were included in this study. All the cases of small cell osteosarcoma showed strong nuclear expression of SATB2 associated with negativity for CD99 antibody or weak, cytoplasmic staining in few neoplastic cells. Reverse transcription-polymerase chain reaction was negative for EWS-FLI1 type 1-2, EWS-ERG type 1, and CIC-DUX4 in the 10 available cases of small cell osteosarcoma analyzed. Fluorescence in situ hybridization analysis was feasible with a readable signal in 13 cases of small cell osteosarcoma, and none of these cases showed any EWSR1 and FUS gene rearrangements. In conclusion, it appears extremely useful to combine IHC analysis of SATB2 and CD99 with molecular analysis of Ewing sarcoma-associated genetic aberrations, to differentiate small cell osteosarcoma from other small round cell malignancies of bone. The strong IHC expression of SATB2 associated with CD99 immunonegativity and the absence of EWSR1 and FUS gene rearrangements in small cell osteosarcoma argues against the existence of a morphologic/genetic continuum with Ewing sarcoma.

MDM2 and CDK4 expression in periosteal osteosarcoma.

Periosteal osteosarcoma is defined by the World Health Organization as an intermediate-grade, malignant, cartilaginous, and bone-forming neoplasm arising on the surface of bone. Unlike other subtypes of osteosarcoma, no data have been published about mouse double minute 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) expression. For this reason, we evaluated the molecular and immunohistochemical features of MDM2 and CDK4 in 27 cases relative to 20 patients with a diagnosis of periosteal osteosarcoma, surgically treated at the Rizzoli Institute between 1981 and 2014. When possible, these results were compared with the MDM2 amplification status as determined by fluorescence in situ hybridization (FISH). All but 1 case (26/27, 96.3%) were negative for MDM2 protein using immunohistochemistry both in primary and in recurrent periosteal osteosarcoma, whereas gene amplification of MDM2 was not detected in any tumor analyzed (10 cases). The positive immunohistochemical case shows a weak/moderate focal nuclear expression of MDM2 antibody in the prevalent cartilaginous component and in the spindle cells of peripheral fibroblastic areas associated with osteoid production in a primary periosteal osteosarcoma. CDK4 immunohistochemical expression was negative in all 27 cases. This retrospective analysis has demonstrated that MDM2 and CDK4 are very rarely expressed in primary and recurrent periosteal osteosarcomas and therefore do not appear to be molecules central to the control of cancer development, growth, and progression in periosteal osteosarcoma. Therefore, when compared with low-grade central and parosteal osteosarcomas, MDM2 and CDK4 markers cannot be used diagnostically to differentiate this subtype of osteosarcoma.

Diagnostic utility of molecular investigation in extraskeletal myxoid chondrosarcoma.

Extraskeletal myxoid chondrosarcoma is characterized by the reciprocal chromosomal translocation t(9;22) and the resultant fused gene EWS RNA-binding protein 1 and nuclear receptor subfamily 4, group A, member 3 (EWSR1-NR4A3). A second cytogenetic rearrangement t(9;17) involves the genes NR4A3 and TAF 15 RNA polymerase II, TATA box binding protein (TBP)-associated factor (TAF15). Less frequent fusion transcript variants of the NR4A3 gene, transcription factor 12 (TCF12)-NR4A3 and TRK-fused gene (TFG)-NR4A3, are associated with t(9;15) and t(9;3) respectively. The samples from 42 patients with extraskeletal myxoid chondrosarcoma were examined for the presence of EWSR1-NR4A3, TAF15-NR4A3, TCF12-NR4A3, and TFG-NR4A3 fusion transcripts by using RT-PCR. Fluorescence in situ hybridization was performed to analyze the status of EWSR1 and NR4A3 genes. The fusion transcripts were detected in 34 of 42 samples (81%); the presence of an EWSR1 or NR4A3 gene rearrangements were detected in 8 of 42 samples (19%) which had tested negative for all fusion transcripts detected by RT-PCR. Of the 34 samples evaluable for fusion transcripts, 23 yielded positive results for EWSR1-NR4A3, 10 for TAF15-NR4A3, and 1 for TCF12-NR4A3. The combination of RT-PCR and fluorescence in situ hybridization on frozen and paraffin-embedded tissue is a sensitive and specific method for molecular detection of recurrent translocations and is an important ancillary method to establish the diagnosis of extraskeletal myxoid chondrosarcoma.