p53 as a Potential Actionable Target in Myxofibrosarcoma: A Molecular and Pathologic Review of a Single-Institute Series.

Myxofibrosarcoma (MFS) is a common adult soft tissue sarcoma characterized by high-local recurrence rate, poorly understood molecular pathogenesis, lack of specific prognostic markers, and effective targeted therapies. To gain further insights into the disease, we analyzed a well-defined group of 133 primary MFS cases. Immunohistochemical (IHC) staining for p53, MET, RET, and RB was performed. Twenty-five cases were analyzed by targeted resequencing of known cancer driver hotspot mutations, whereas 66 and 64 MFSs were examined for the presence of genetic variants in TP53 and MET gene, respectively. All clinical, histologic, immunostaining, and genetic variables were analyzed for their impact on 5-years overall survival (OS) and 5-years event-free survival (EFS). In our series, no grade I tumors relapsed and high grade are related to a positive MET immunostaining (P = .034). Both local recurrence (P = .038) and distal metastases (P = .016) correlated to the presence of "single nucleotide variant (SNV) plus copy number variation (CNV)" in TP53. Multivariate analysis revealed that age (>60 years), metastasis at presentation, and positive IHC-p53 signal are risk factors for a poor OS (P = .003, P = .000, and P = .002), whereas age (>60 years), synchronous metastasis, and tumor size (>10 cm) predict an unfavorable 5-years EFS (P = .011, P = .000, and P = .023). Considering the smaller series (n = 66) that underwent molecular screening, the presence of "SNV+CNV" in TP53 represents a risk factor for a worse 5-years EFS (hazard ratio, 2.5; P = .017). The present series confirms that TP53 is frequently altered in MFS (86.4% of cases), appearing to play an important role in MFS tumorigenesis and being a potentially drugable target. A positive p53 immunostainings is related to a poor diagnosis, and it is the presence of a single nucleotide genetic alterations in TP53 that is essential in conferring MFS an aggressive phenotype, thus supporting the use of molecular profiling in MFS to better define the role of p53 as a prognostic factor.

Histological and imaging features of myoepithelial carcinoma of the bone and soft tissue.

OBJECTIVE: To depict histological and imaging features of myoepithelial carcinoma of the bone and soft tissue. MATERIALS AND METHODS: We retrospectively examined histological features in 22 patients with myoepithelial carcinoma of the bone (4 patients) and soft tissue (18 patients) at a single institution. Imaging analysis of 15 patients (bone, 3 patients; soft tissue, 12 patients;) with preoperative images involved classifying lytic bone lesions via the modified Lodwick-Madewell classification; the growth patterns of soft tissue lesions were classified as well-defined, focally invasive, or diffusely invasive. RESULTS: Local recurrence occurred in eight out of 22 patients (36.3%). Four of 22 patients (18.2%) had metastasis at presentation, whereas 11 of 22 patients (50.0%) had distant metastasis during follow-up. Severe cytological pleomorphism was observed in 14 of 22 patients (63.6%), and 10 of 22 tumors (45.5%) showed ≥ 10 mitoses/10 high-power fields. Vascular invasion was observed in 10 of 22 patients (45.5%). Extracapsular/extraskeletal infiltration into the surrounding tissues was assessed in 20 patients, with 14 of them (70%) showing infiltration beyond the tumor border. Regarding imaging of bone lesions, two patients had Ludwick type IIIB, whereas one patient had type II. The growth pattern of soft tissue lesions was well-defined in two patients (16.7%), focally invasive in seven patients (58.3%), and diffusely invasive in three (25.0%) out of 12 patients. CONCLUSION: Myoepithelial carcinoma of the bone and soft tissue presents high risk of local recurrence and distant metastasis. Histological and imaging features might be important to understand the aggressive behavior of the tumor.

A reduction in tumor volume exceeding 65% predicts a good histological response to neoadjuvant chemotherapy in patients with Ewing sarcoma.

OBJECTIVE: No consensus exists for tumor volume response criteria in patients with Ewing sarcoma. This study aimed to identify an optimal cutoff for predicting a good histological response by analyzing tumor volume changes and tumor necrosis after neoadjuvant chemotherapy. MATERIALS AND METHODS: We performed a retrospective analysis of 184 Ewing sarcoma patients, analyzing tumor volume changes before and after neoadjuvant chemotherapy. Patients were divided into two groups based on histological response: good (tumor necrosis ≥ 95%) and poor (tumor necrosis < 95%) responders. The receiver operating characteristic (ROC) area under the curve (AUC) method was used to determine the optimal thresholds for predicting the histological response. Additionally, the prognostic value of this cutoff for relapse-free survival was assessed. RESULTS: Out of 184 patients, 83 (45%) had tumor necrosis ≥ 95%, while 101 (55%) had tumor necrosis < 95%. ROC analysis identified the optimal cutoff for a good histological response as over 65% tumor volume reduction (AUC = 0.69; p < 0.001). Patients with volume reduction of ≥ 65% had a higher likelihood of a good histological response than those with lesser reductions (p = 0.004; odds ratio = 2.61). Multivariable analysis indicated a correlation between poor histological response and reduced relapse-free survival (hazard ratio = 2.17; p = 0.01), while tumor volume reduction itself did not impact survival. CONCLUSION: We reported that a tumor volume reduction of ≥ 65% was able to predict a good histological response in Ewing sarcoma patients. We recommend preoperative tumor volume assessment to identify patients at greater risk for poor histological response who could benefit from more intensive chemotherapy protocols or additional radiotherapy.

Fusion transcriptome profiling defines the monoclonal origin of multifocal epithelioid haemangioma of bone.

AIMS: Epithelioid haemangioma (EH) of bone remains a highly controversial entity. Indeed, the WHO classifies EHs of soft tissues as benign tumours, whereas bone EHs are considered intermediate-locally aggressive tumours due to common multifocal presentation and local destructive growth. To gain insights into the clinical behaviour and biology of EH of bone we retrospectively analysed 42 patients treated in a single institution from 1978 to 2021. METHODS AND RESULTS: Multifocal presentation was detected in 17 of 42 patients (40%) primarily as synchronous lesions. Patients were treated with curettage (57%), resection (29%) or biopsy, followed by radiotherapy or embolisation (14%). Follow-up (minimum 24 months) was available for 38 patients, with only five local recurrences (13%) and no death of disease. To clarify whether the synchronous bone lesions in multifocal EH represent multicentric disease or clonal dissemination, four cases were profiled by RNA-sequencing. Separate lesions from the same patient, which showed a similar transcriptional profile, expressed the same fusion transcript (involving FOS or FOSB) with identical gene breakpoints. CONCLUSIONS: These results indicate that, in EH of bone, multifocal lesions are clonally related and therefore represent the spread of a same neoplastic clone rather than simultaneous independent tumours. This finding is in apparent contradiction with the benign clinical course of the disease, and suggests that tumour dissemination in bone EH probably reflects a phenomenon of passive spreading, with tumour cells colonising distal sites while maintaining their benign biological nature.

Datasets for the reporting of primary tumour in bone: recommendations from the International Collaboration on Cancer Reporting (ICCR).

BACKGROUND AND OBJECTIVES: Bone tumours are relatively rare and, as a consequence, treatment in a centre with expertise is required. Current treatment guidelines also recommend review by a specialised pathologist. Here we report on international consensus-based datasets for the pathology reporting of biopsy and resection specimens of bone sarcomas. The datasets were produced under the auspices of the International Collaboration on Cancer Reporting (ICCR), a global alliance of major (inter-)national pathology and cancer organisations. METHODS AND RESULTS: According to the ICCR's process for dataset development, an international expert panel consisting of pathologists, an oncologic orthopaedic surgeon, a medical oncologist, and a radiologist produced a set of core and noncore data items for biopsy and resection specimens based on a critical review and discussion of current evidence. All professionals involved were bone tumour experts affiliated with tertiary referral centres. Commentary was provided for each data item to explain the rationale for selecting it as a core or noncore element, its clinical relevance, and to highlight potential areas of disagreement or lack of evidence, in which case a consensus position was formulated. Following international public consultation, the documents were finalised and ratified, and the datasets, including a synoptic reporting guide, were published on the ICCR website. CONCLUSION: These first international datasets for bone sarcomas are intended to promote high-quality, standardised pathology reporting. Their widespread adoption will improve the consistency of reporting, facilitate multidisciplinary communication, and enhance comparability of data, all of which will help to improve management of bone sarcoma patients.

Giant cell tumor of bone with secondary aneurysmal bone cyst does not have a higher risk of local recurrence.

BACKGROUND: Fluid-fluid levels (FFLs) is found in 10%-16% of giant cell tumor of bone (GCTB), and the presence of FFLs raises the suspicion of GCTB with secondary aneurysmal bone cyst (ABC), which can lead to increased intraoperative bleeding and, blurring the operative field, be associated with a risk of local recurrence. The first objective of this study is to determine whether secondary ABC is associated with a higher risk of local recurrence after curettage in patients with GCTB of the extremities. The second objective of this study is to investigate the sensitivity, specificity, positive predictive value, and negative predictive value of the presence of FFLs detected on magnetic resonance imaging (MRI) to diagnose secondary ABC associated with GCTB. METHODS: Two hundred and eighty patients with GCTB of the extremities who underwent curettage at the authors' institutions between 1980 and 2021 were included in this study. RESULTS: Secondary ABC was found in 36 of 280 patients (12.9%) and local recurrence occurred in 66 of 280 patients (23.6%). Multivariate analysis showed no significant correlation between secondary ABC and local recurrence (hazard ratio [HR]: 1.87 (95% confidence interval [CI]: 1.00-3.53]; p = 0.051). Preoperative MRI revealed FFLs in 13 of 82 patients (15.9%). Sensitivity, specificity, positive predictive value, and negative predictive value of FFLs detected on preoperative MRI to diagnose secondary ABC were 36.8%, 90.5%, 53.8%, and 82.6%, respectively. CONCLUSION: The results of this study showed that secondary ABC does not increase the risk of local recurrence after curettage in patients with GCTB of the extremities. Although rare, FFLs were present in patients with GCTB and half of those with FFLs detected on preoperative MRI had secondary ABC.

Epigenomic and somatic mutations of pituitary tumors with clinical and pathological correlations in 111 patients.

OBJECTIVE: To profile clinically non-aggressive and aggressive pituitary adenomas (PAs)/pituitary neuroendocrine tumours (PitNETs) and pituitary carcinomas for somatic mutations and epigenetic alterations of genes involved in cell proliferation/differentiation, microRNAs (miRNA)/long noncoding RNA (LncRNA)-post-transcriptional regulators and therapy targets. DESIGN: Retrospective observational study. PATIENTS AND MEASUREMENTS: A total of 64 non-aggressive and 41 aggressive PAs/PitNETs and 6 pituitary carcinomas treated by endoscopic surgery with ≥1-year follow-up were included. Somatic mutations of 17 genes and DNA methylation of 22 genes were assessed. Ten normal pituitaries were used as control. RESULTS: We found at least one mutation in 17 tumours, including 6/64 non-aggressive, 10/41 aggressive PAs/PitNETs, and 1/6 pituitary carcinoma. AIP (N = 6) was the most frequently mutated gene, followed by NOTCH (4), and TP53 (3). Hypermethylation of PARP15, LINC00599, ZAP70 was more common in aggressive than non-aggressive PAs/PITNETs (p < .05). Lower levels of methylation of AIP, GNAS and PDCD1 were detected in aggressive PAs/PITNETs than non-aggressive ones (p < .05). For X-linked genes, males presented higher level of methylation of FLNA, UXT and MAGE family (MAGEA11, MAGEA1, MAGEC2) genes in aggressive vs. non-aggressive PAs/PITNETs (p < .05). In pituitary carcinomas, methylation of autosomal genes PARP15, LINC00599, MIR193 and ZAP70 was higher than in PAs/PITNETs, while X-linked genes methylation level was lower. CONCLUSIONS: Somatic mutations and methylation levels of genes involved in cell proliferation/differentiation, miRNA/LncRNA-post-transcriptional regulators and targets of antineoplastic therapies are different in non-aggressive and in aggressive PAs/PitNETs. Methylation profile also varies according to gender. Combined genetic-epigenetic analysis, in association with clinico-radiological-pathological data, may be of help in predicting PA/PitNET behaviour.

Chondroblastoma-like osteosarcoma: a clinicopathological and molecular study of a rare osteosarcoma variant.

OBJECTIVE: Chondroblastoma-like osteosarcoma (CBLOS) is a rare and poorly understood variant of OS. We examined the clinicopathological, immunohistochemical and molecular features of six CBLOSs to highlight the differences with conventional high-grade OS (CHGOS) and CB, including CB with aggressive features. METHODS: We performed histone 3.3 mutation analysis by gene sequencing and/or immunohistochemistry in all cases, while whole exome sequencing (WES) was performed on two CB-like osteosarcomas and 11 conventional high-grade OS. RESULTS: CBLOSs were predominantly localised at acral sites and involved mainly male subjects with a mean age of 29 years. One patient who had metastases at presentation died of disease, while another patient who developed multiple local recurrences and lung metastases was alive with no evidence of disease (ANED) at 294 months. The remaining patients were ANED after a mean interval of 70.8 months. Histologically, all CBLOS presented aggressive features, including nuclear atypia and infiltrative growth. Immunohistochemistry with H3F3 K36M mutant antibody was negative in all CBLOSs, and none of the five tumours tested by gene sequencing had H3F3B mutations. Conversely, all CBs presented the H3F3B K36M variant and were positive for immunostaining with the H3F3 K36M antibody. Two CBLOSs analysed by WES differed in amount and type of mutation from 11 cases of CHGOS. Moreover, CBLOSs showed lower copy number alteration (CNA) score values than CHGOSs. CONCLUSIONS: CBLOS presents a different genetic background and a less aggressive clinical behaviour in comparison with CHGOS. Search of the H3F3B K36M mutation is useful in the differential diagnosis with CB.

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.

Effect of adjuvant chemotherapy on periosteal osteosarcoma: a systematic review.

BACKGROUND AND OBJECTIVE: The effects of adjuvant chemotherapy on periosteal osteosarcoma are controversial. Therefore, we conducted a systematic review of studies comparing mortality, local recurrence, distant metastasis and secondary malignancy incidence among patients who underwent surgery and (neo-) adjuvant chemotherapy or surgery alone for periosteal osteosarcoma without distant metastases at diagnosis. METHODS: Of the 210 studies identified in the search, 13 were included in this study, involving 291 patients with periosteal osteosarcoma in total. RESULTS: The mortality rates in the surgery and (neo-) adjuvant chemotherapy and surgery alone groups were 11.3% (8/71) and 16.3% (16/98), respectively. The overall pooled odds ratio was 0.89 (P = 0.800). The local recurrence rate in the surgery and (neo-) adjuvant chemotherapy group was 12.1% (8/66), while that in the surgery alone group was 17.6% (13/74). The overall pooled odds ratio was 1.31 (P = 0.601). The distant metastasis rate in the surgery and (neo-) adjuvant chemotherapy group was 15.2% (10/66) and that in the surgery alone group was 10.8% (8/74). The overall pooled odds ratio was 1.51 (P = 0.444). The incidence of secondary malignancy in the surgery and (neo-) adjuvant chemotherapy group was 7.6% (9/118) and that in the surgery alone group was 2.7% (2/74). The overall pooled odds ratio was 2.29 (P = 0.187). CONCLUSIONS: Adjuvant chemotherapy did not appear to improve the prognosis of patients with periosteal osteosarcoma. No association was found between the use of adjuvant chemotherapy and development of secondary malignancies.

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.

YAP1-TFE3-fused hemangioendothelioma: a multi-institutional clinicopathologic study of 24 genetically-confirmed cases.

YAP1-TFE3-fused hemangioendothelioma is an extremely rare malignant vascular tumor. We present the largest multi-institutional clinicopathologic study of YAP1-TFE3-fused hemangioendothelioma to date. The 24 cases of YAP1-TFE3-fused hemangioendothelioma showed a female predominance (17 female, 7 male) across a wide age range (20-78 years old, median 44). Tumors were most commonly located in soft tissue (50%), followed by bone (29%), lung (13%), and liver (8%), ranging from 3 to 115 mm in size (median 40 mm). About two-thirds presented with multifocal disease, including 7 cases with distant organ metastasis. Histopathologically, we describe three dominant architectural patterns: solid sheets of coalescing nests, pseudoalveolar and (pseudo)vasoformative pattern, and discohesive strands and clusters of cells set in a myxoid to myxohyaline stroma. These patterns were present in variable proportions across different tumors and often coexisted within the same tumor. The dominant cytomorphology (88%) was large epithelioid cells with abundant, glassy eosinophilic to vacuolated cytoplasm, prominent nucleoli and well-demarcated cell borders. Multinucleated or binucleated cells, prominent admixed erythrocytic and lymphocytic infiltrates, and intratumoral fat were frequently present. Immunohistochemically, ERG, CD31, and TFE3 were consistently expressed, while expression of CD34 (83%) and cytokeratin AE1/AE3 (20%) was variable. CAMTA1 was negative in all but one case. All cases were confirmed by molecular testing to harbor YAP1-TFE3 gene fusions: majority with YAP1 exon 1 fused to TFE3 exon 4 (88%), or less commonly, TFE3 exon 6 (12%). Most patients (88%) were treated with primary surgical resection. Over a follow-up period of 4-360 months (median 36 months) in 17 cases, 35% of patients remained alive without disease, and 47% survived many years with stable, albeit multifocal and/or metastatic disease. Five-year progression-free survival probability was 88%. We propose categorizing YAP1-TFE3-fused hemangioendothelioma as a distinct disease entity given its unique clinical and histopathologic characteristics in comparison to conventional epithelioid hemangioendothelioma.

Extraskeletal Myxoid Chondrosarcoma with Molecularly Confirmed Diagnosis: A Multicenter Retrospective Study Within the Italian Sarcoma Group.

BACKGROUND: Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain origin, marked by specific chromosomal translocations involving the NR4A3 gene, and usually characterized by an indolent course. Surgery (with or without radiotherapy) is the treatment of choice in localized disease. The treatment for advanced disease remains uncertain. In order to better evaluate prognostic factors and outcome, a retrospective pooled analysis of patients with EMC treated at three Italian Sarcoma Group (ISG) referral centers was carried out. METHODS: All patients with localized EMC surgically treated from 1989 to 2016 were identified. Diagnosis was centrally reviewed according to WHO 2013. Only patients with NR4A3 rearrangement were included. RESULTS: Sixty-seven patients were identified: 13 (20%) female, 54 (80%) male. Median age was 56 years (range 18-84). Numbers and type of translocation were: 50 (80%) NR4A3-EWS, 10 (16%) NR4A3-TAF15, 1 (2%) NR4A3-TCF12, and 1 (2%) NR4A3-TFG. Median follow-up was 55 months (range 2-312). Five- and ten-year overall survival rates were 94% (86-100 95%CI) and 84% (69-98 95%CI). Thirty-five (52%) patients relapsed: 9 had local recurrence (LR) and 26 had distant metastasis (5 with concomitant LR). The 5- and 10-year disease-free survival rates (DFS) were 51% (38-65 95%CI) and 20% (7-33 95%CI). Size of the primary tumor was significantly related to distant metastasis-free survival (DMFS) (p = 0.004). Patients carrying the NR4A3-EWS translocation had a trend in favor of better DFS (p = 0.08) and DMFS (p = 0.09) compared with the patients with NR4A3-TAF15. CONCLUSIONS: Prolonged survival can be expected in patients with EMC, in spite of a high rate of recurrence. Size is significantly associated with distant relapse. The type of NR4A3 translocation could influence outcome.

Primary sclerosing epithelioid fibrosarcoma of the spine: a single-institution experience.

AIMS: To present our experience on spinal sclerosing epithelioid fibrosarcoma (SEF) and review the existing literature pertaining to SEF of the spine. METHODS AND RESULTS: Six cases of spinal SEF were reviewed, and a literature search of all primary SEFs of the spine was performed. All tumours occurred in adults (median age, 41 years) and were located all along the spine, the lumbar vertebrae being the most commonly involved. All patients presented with pain that they had experienced for months. The mean tumour size at diagnosis was 52 mm. Five tumours showed a spectrum of microscopic features consistent with pure SEF, and one showed a hybrid morphology with areas of low-grade fibromyxoid sarcoma. All were diffusely and strongly positive for mucin 4. Two cases were initially misdiagnosed as epithelioid haemangioendothelioma and aggressive chondroblastoma. Fluorescence in-situ hybridisation showed rearrangements of either FUS or EWSR1 in four cases. Reverse transcription polymerase chain reaction showed the presence of FUS-CREB3L1 and EWSR1-CREB3L1 fusion transcripts in two cases and one case, respectively. Of five patients with follow-up data available, two developed one or more local recurrences and three patients had metastatic disease. Distant metastases were mainly to other osseous locations, followed by lungs and lymph nodes. At last follow-up, three patients had died of disease and one was alive with multiple metastases. CONCLUSIONS: SEF is an aggressive sarcoma that can involve the spine. It is important to recognise the spine as the primary location of SEF, in order to avoid misdiagnosis as more common primary spinal neoplasms, which can impact on therapeutic approaches.

Malignancy in giant cell tumor of bone: analysis of an open-label phase 2 study of denosumab.

BACKGROUND: Giant cell tumor of bone (GCTB) is a rare osteoclastogenic stromal tumor. GCTB can rarely undergo malignant transformation. This post hoc analysis evaluated and classified malignancies in patients with GCTB who received denosumab. METHODS: This analysis was conducted on patients with pathologically confirmed GCTB and measurable active disease treated with denosumab 120 mg subcutaneously once every 4 weeks, with loading doses on study days 8 and 15, as part of a phase 2, open-label, multicenter study. We identified potential cases of malignancy related to GCTB through an independent multidisciplinary review or medical history, associated imaging or histopathologic reports, and disease course. The findings were summarized and no statistical analysis was performed. RESULTS: Twenty of five hundred twenty-six patients (3.8%) who received at least one dose of denosumab were misdiagnosed with GCTB that was later discovered to be malignancies: five primary malignant GCTB, five secondary malignant GCTB, four sarcomatous transformations, and six patients with other malignancies (giant cell-rich osteosarcoma, undifferentiated pleomorphic sarcoma, spindle cell sarcoma, osteogenic sarcoma, phosphaturic mesenchymal tumor of mixed connective tissue type, and fibrosarcoma/malignant fibrous histiocytoma). Many malignancies were present before denosumab was initiated (8 definitive cases, 7 likely cases), excluding potential involvement of denosumab in these cases. Signs associated with potential misdiagnoses of GCTB included poor mineralization with denosumab treatment, rapid relapse in pain, or a failure of the typical dramatic improvement in pain normally observed with denosumab. CONCLUSIONS: Although rare, GCTB can undergo malignant transformation, and rates in this study were consistent with previous reports. Signs of poor mineralization or lack of response to denosumab treatment may warrant close monitoring. TRIAL REGISTRATION: clinicaltrials.gov , ( NCT00680992 ). Registered May 20, 2008.

A practical algorithm to predict postsurgical recurrence and progression of pituitary neuroendocrine tumours (PitNET)s.

OBJECTIVE: Pituitary neuroendocrine tumours (PitNET)s can be aggressive, thus presenting local invasion, postsurgical recurrence and/or resistance to treatment, responsible for significant morbidity. The study aimed at identifying prognostic factors of postsurgical outcome using data-driven classification of patients. DESIGN: Retrospective observational study. METHODS: Clinicopathological and radiological data of patients with PitNET treated via endoscopic endonasal surgery were collected. Tumour recurrence/progression and progression-free survival were assessed by classification tree analysis (CTA) and Kaplan-Meier curves, respectively. Histological subtype, cavernous/sphenoid sinus invasion, mitosis, Ki-67, p53, Trouillas' grading, degree of tumour exeresis and postsurgery disease activity were also evaluated. RESULTS: A total of 1066 (466 gonadotroph, 287 somatotroph, 148 lactotroph, 157 corticotroph and 8 thyrotroph) tumours were included; 21.7% invaded the cavernous/sphenoid sinus. Based on Trouillas' classification, 64.3% were grade 1a, 14.2% 1b, 16.1% 2a, and 5.4% 2b; 18.3% had >2/10 HPF mitoses, 24.9% had Ki-67 ≥3%; 15.8% were positive for p53. Exeresis was radical in 81.2% of the cases. Median follow-up was 59.2 months. At last evaluation, 79.4% of the patients were cured; 20.6% had disease persistence, controlled by medical treatment in 18.3% of them. Disease recurrence/progression was recorded in 10.9% of the cases. CTA identified 5 distinct patient subgroups with different risk of disease recurrence/progression. Grade 2 of the Trouillas' grading, >2/10 HPF mitoses, Ki-67 ≥3%, p53 protein expression (P < .001), tumour invasion (P = .002) and ACTH-subtype (P = .003) were identified as risk factors of disease recurrence/progression. CONCLUSIONS: The combined evaluation of Trouillas' grading, proliferation indexes and immunohistochemistry appears promising in the prediction of surgical outcome in PitNET.

Peculiar pathological, radiological and clinical features of skull-base de-differentiated chordomas. Results from a referral centre case-series and literature review.

AIMS: De-differentiated chordoma is an uncommon and incompletely characterised aggressive neoplasm. Only a few cases originating from the skull base have been reported. METHODS AND RESULTS: All consecutive cases of skull-base de-differentiated chordomas treated surgically in a referral centre from January 1990 to June 2019 were retrospectively evaluated to assess peculiar pathological, radiological and clinical features. Patient data were retrieved from paper and electronic records. Six cases (two male, four female; mean age at surgery = 46 years, range = 35-64), treated surgically at our institution were identified. Transformation to de-differentiated chordomas occurred after radiation therapy in three cases (mean = 13.6 years after treatment, range = 5-25), two during tumour progression, while one was de-novo. Magnetic resonance imaging and surgical examination revealed the presence of two different tumour components, corresponding to the conventional and de-differentiated portion on histological examination. The de-novo case presented a PIK3CA mutation. DNA methylation analysis revealed consistent epigenetic changes in TERT, MAGEA11 and UXT. Prognosis was poor, as five of six patients died after surgery and radiation therapy, with a mean overall survival of 29 months (range = 11-52). CONCLUSIONS: Skull-base de-differentiated chordomas are extremely rare and aggressive neoplasms with characteristic magnetic resonance imaging, surgical and histological features. Therefore, an early and accurate histological diagnosis is of paramount relevance. Molecular analysis appears promising to define mechanisms involved in tumour de-differentiation.

Synovial chondrosarcoma: a single-institution experience with molecular investigations and review of the literature.

AIMS: To evaluate the available diagnostic histological criteria for synovial chondrosarcoma and to screen for the presence of IDH1/IDH2 mutations in a series of cases of this malignant cartilaginous neoplasm. METHODS AND RESULTS: Ten cases of synovial chondrosarcoma diagnosed at our institute were reviewed. At presentation, all tumours occurred in adults (median age, 62 years). The most common location was the knee joint (five cases), and the size at diagnosis ranged from 30 mm to 170 mm. Eight patients had secondary synovial chondrosarcomas associated with pre-existing/recurrent or concomitant synovial chondromatosis. Five patients had local recurrences and three had lung metastases. All patients with intralesional excisions developed local recurrences, whereas those who underwent wide resections did not. At last follow-up (mean, 91 months), available for nine patients, seven patients were alive and disease-free, one patient had died of disease, and one was alive with paravertebral metastases. Frequent histological features observed included loss of clustering of chondrocytes (nine cases), the presence of variable amounts of myxoid matrix (eight cases), peripheral hypercellularity (eight cases), tumour necrosis (six cases), and spindling of chondrocytes (four cases). Of the seven cases for which it was possible to evaluate bone permeation, six showed infiltration of bone marrow. All seven cases screened for mutations of exon 4 of IDH1 and IDH2 were found to be wild-type. CONCLUSIONS: Histological criteria in correlation with clinical and radiological features allow the recognition of synovial chondrosarcoma. IDH1/IDH2 mutations were not present in synovial chondrosarcoma. Adequate surgical margins are important for disease control.

Post-radiotherapy vascular lesions of the breast: immunohistochemical and molecular features of 74 cases with long-term follow-up and literature review.

AIMS: A wide range of post-radiotherapy (RT) vascular lesions can occur, ranging from benign lymphangiomatous papules of the skin (BLAPs), to atypical vascular lesions (AVLs) and post-RT angiosarcomas (ASs). The relationship between benign and malignant post-RT breast lesions and their prognostic features are still controversial. The aims of this study were to investigate the relationship between benign and malignant mammary post-RT vascular lesions and to define post-RT AS prognostic features. METHODS AND RESULTS: Seventy-four post-RT vascular lesion cases were obtained and stained with antibodies against CD34, CD31, D2-40, Ki67, and c-Myc. Mutational analysis was performed by deep sequencing for the following genes: KRAS, NRAS, HRAS, BRAF, PIK3CA, TP53, NOTCH1, PTEN, CDKN2A, EGFR, AKT1, CTNNB1, hTERT, and PTPRB. Post-RT AS cases were graded according to a previously reported breast AS grading system. AVL cases showed a low number of HRAS and hTERT mutations, whereas post-RT AS cases showed a high frequency of EGFR, TP53, HRAS and hTERT mutations. On follow-up, all BLAP and AVL patients were alive with no evidence of disease. Post-RT AS 5-year overall survival declined with the increase in grade, as follows: 85.7% for grade 1, 83.3% for grade 2, and 40.4% for grade 3. CONCLUSIONS: Our findings confirm that BLAP and AVL have a good prognosis, and that post-RT AS prognosis is strongly related to histological grading. On molecular analysis, AVL and post-RT AS shared HRAS and hTERT mutations, suggesting a relationship between the two lesions.

Primary malignant ossifying fibromyxoid tumour of the bone. A clinicopathologic and molecular report of two cases.

OBJECTIVE: To report the exceptional occurrence of ossifying fibromyxoid tumour (OFMT) as a primary bone lesion. OFMT is a rare soft tissue tumour of uncertain differentiation and variable malignant potential, that occurs in adults with a slight male predominance. It is typically located in the subcutis or in the skeletal muscles of the extremities, followed by trunk or head and neck. METHODS: Two cases of OFMT proven to arise from bone are presented. The first is a 65-year old female with a history of rib "osteosarcoma", presenting with an inferior lobe left lung mass. The second is a man with a lytic lesion of the 5th cervical vertebra that recurred shortly after resection. Following H&E and immunohistochemical examination, tumour samples were analysed by NGS and by break-apart FISH to detect rearrangement of the PHF1 and TFE3 genes. RESULTS: PHF1 gene-rearrangement was identified by FISH on both the primary and the metastatic lesion of first patient. NGS identified a PHF1(intron1) and EPC1 (exon 10) fusion transcript later confirmed by positive PHF1 rearrangement on FISH in the second case. CONCLUSIONS: The demonstration of PHF1 gene rearrangements represents a fundamental ancillary diagnostic test when presented with challenging examples of OFMT.