Biology and Management of High-Grade Chondrosarcoma: An Update on Targets and Treatment Options.

This review provides an overview of histopathology, clinical presentation, molecular pathways, and potential new systemic treatments of high-grade chondrosarcomas (CS), including grade 2−3 conventional, dedifferentiated, and mesenchymal CS. The diagnosis of CS combines radiological and histological data in conjunction with patient clinical presentations. Conventional CS is the most frequent subtype of CS (85%) and represents about 25% of primary bone tumors in adults; they can be categorized according to their bone location into central, peripheral, and periosteal chondrosarcomas. Central and peripheral CS differ at the molecular level with either IDH1/2 mutations or EXT1/2 mutations, respectively. CDKN2A/B deletions are also frequent in conventional CS, as well as COL2A1 mutations. Dedifferentiated CS develops when low-grade conventional CS transforms into a high-grade sarcoma and most frequently exhibits features of osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma. Their molecular characteristics are similar to conventional CS. Mesenchymal CS is a totally different pathological entity exhibiting recurrent translocations. Their clinical presentation and management are different too. The standard treatment of CSs is wide en-bloc resection. CS are relatively radiotherapy resistant; therefore, doses >60 Gy are needed in an attempt to achieve local control in unresectable tumors. Chemotherapy is possibly effective in mesenchymal chondrosarcoma and is of uncertain value in dedifferentiated chondrosarcoma. Due to resistance to standard anticancer agents, the prognosis is poor in patients with metastatic or unresectable chondrosarcomas. Recently, the refined characterization of the molecular profile, as well as the development of new treatments, allow new therapeutic options for these rare tumors. The efficiency of IDH1 inhibitors in other malignancies suggests that these inhibitors will be part of IDH1/2 mutated conventional CS management soon. Other treatment approaches, such as PIK3-AKT-mTOR inhibitors, cell cycle inhibitors, and epigenetic or immune modulators based on improving our understanding of CS molecular biology, are emerging.

Prognostic factors of the synovial sarcoma of the extremities: imaging does matter.

OBJECTIVES: Synovial sarcomas (SS) of the extremities are rare soft tissue sarcomas that are more common in young adults. We deciphered the imaging phenotype of SS with the aim to determine if imaging could provide an incremental value to currently known prognostic factors (PF)-age and histological grade-to predict long-term overall survival (OS). METHODS: This retrospective multicenter study included consecutive pediatric and adult patients with synovial sarcomas of the extremities from December 2002 to August 2020. Inclusion criteria were (i) a follow-up greater than 5 years and (ii) available pre-therapeutic MRI. A subset analysis included MRI and CT-scan. Clinical, pathological, and imaging variables were collected in all patients. The primary endpoint was to evaluate the association of these variables with OS using univariate and multivariate Cox regressions. RESULTS: Out of 428 patients screened for eligibility, 98 patients (mean age: 37.1 ± 15.2 years) were included (MRI: n = 98/98, CT scan: n = 34/98; 35%). The median OS was 75.25 months (IQR = 55.50-109.12) and thirty-six patients (n = 36/98;37%) died during follow-up. The recurrence rate was 12.2% (n =12/98). SS lesions were mostly grade 2 (57/98; 58%). On MRI, SS had a mean long-axis diameter of 67.5 ± 38.3 mm. On CT scan, 44% (15/34) were calcified. Grade (hazard ratio [HR] = 2.71; 95%CI = 1.30-5.66; p = 0.008), size of the lesions evaluated on MRI (HR = 1.02; 95% CI = 1.01-1.03; p < 0.001), and calcifications on CT scan (HR = 0.10; 95% CI = 0.02-0.50; p = 0.005) were independent PF of OS. CONCLUSIONS: This study demonstrated that imaging biomarkers can be used to predict long-term outcome in patients with SS. Strikingly, the presence of calcifications on CT scan is associated with favorable outcome and provides an incremental value over existing PF such as age, grade, and size. KEY POINTS: • Beyond its diagnostic value, MRI is a pre-operative prognostic tool in synovial sarcomas of the extremities since the size of the lesion is an important prognostic factor. • Calcifications on CT scans are independently and significantly associated with prolonged overall survival.

[Giant-cell tumor of bone in 2022]. / La tumeur à cellules géantes des os en 2022.

Giant cell tumors of bone (GCTs) are rare mesenchymal tumors classified as intermediate in the WHO 2020 classification, i.e. neither completely benign nor definitely malignant, due to recurrence (frequent) and pulmonary metastases (rare). They involve the end of long bones as well as the axial bones of mature skeletons. They are made of mononuclear stromal tumor cells of (pre-) osteoblastic phenotype, mononuclear cells of the monocyte-macrophage lineage and osteoclast-like multinuclear giant cells responsible for tumor osteolysis. In 95% of cases, the stromal cells have a specific mutation in the H3F3A gene which encodes histone H3.3. The mutated H3.3 G34W protein (90% of cases) can be easily detected by immunohistochemistry, even on small samples. Many tumors or bone pseudotumors contain osteoclast-like giant cells, cells of the bone microenvironment, and should not be confused with GCT: mainly brown tumor of hyperparathyroidism, aneurysmal bone cyst, chondroblastoma, non-ossifying fibroma and central giant cell granuloma.

Novel partners of USP6 gene in a spectrum of bone and soft tissue lesions.

Nodular fasciitis, primary aneurysmal bone cyst, myositis ossificans, and their related lesions are benign tumors that share common histological features and a chromosomal rearrangement involving the ubiquitin-specific peptidase 6 (USP6) gene. The identification of an increasing number of new partners implicated in USP6 rearrangements demonstrates a complex tumorogenesis of this tumor spectrum. In this study on a series of 77 tumors (28 nodular fasciitis, 42 aneurysmal bone cysts, and 7 myositis ossificans) from the database of the French Sarcoma Group, we describe 7 new partners of the USP6 gene. For this purpose, rearrangements were first researched by multiplexed RT-qPCRs in the entire population. A targeted RNA sequencing was then used on samples selected according to a high USP6-transcription level expression estimated by RT-qPCR. Thanks to this multistep approach, besides the common USP6 fusions observed, we detected novel USP6 partners: PDLIM7 and MYL12A in nodular fasciitis and TPM4, DDX17, GTF2I, KLF3, and MEF2A in aneurysmal bone cysts. In order to try to bring to light the role played by the recently identified USP6 partners in this lesional spectrum, their functions are discussed. Taking into account that a traumatic participation has long been mentioned in the histogenesis of most of these lesions and because of their morphological resemblance to organizing granulation reparative tissue or callus, a focus is placed on their relationship with tissue remodeling and, to a lesser extent, with bone metabolism.

Recurrent novel THBS1-ADGRF5 gene fusion in a new tumor subtype "Acral FibroChondroMyxoid Tumors".

Acral soft tissue tumors are common neoplasms, a subset of which pose a diagnostic challenge. We report 10 cases of a previously unrecognized acral benign soft tissue tumor. These tumors arose on the fingers and toes and involved bone in half of cases. Histologically, the tumors were lobulated and displayed an abundant stroma made of variable fibrous, chondroid and myxoid material reminiscent of cartilaginous or myoepithelial differentiation. Tumor cells harbored small round to reniform nuclei with clear chromatin and inconspicuous nucleoli along with scant eosinophilic cytoplasm. The cells were mostly arranged haphazardly in the stroma but also in small clusters. No mitotic activity was detected. No specific feature was identified in recurrent cases. By immunohistochemistry, the cells consistently stained for CD34 (10/10), ERG (9/10), and SOX9 (7/10). Whole RNA sequencing identified a previously undescribed recurrent in frame THBS1-ADGRF5 gene fusion in all cases. The transcript was confirmed by RT-PCR and was not found in the control group of mimickers including soft tissue chondromas. We propose the name of Acral FibroChondroMyxoid Tumors for this new entity.

A subset of epithelioid and spindle cell rhabdomyosarcomas is associated with TFCP2 fusions and common ALK upregulation.

Rhabdomyosarcomas with TFCP2 fusions represent an emerging subtype of tumors, initially discovered by RNA-sequencing. We report herein the clinicopathological, transcriptional, and genomic features of a series of 14 cases. Cases were retrospectively and prospectively recruited and studied by immunohistochemistry (MYF4, MYOD1, S100, AE1/E3, ALK), fluorescence in situ hybridization with TFCP2 break-apart probe (n = 10/14), array-comparative genomic hybridization (Agilent), whole RNA-sequencing (Truseq Exome, Illumina), or anchored multiplex PCR-based targeted next-generation sequencing (Archer® FusionPlex® Sarcoma kit). Patient's age ranged between 11 and 86 years, including 5 pediatric cases. Tumors were located in the bone (n = 12/14) and soft tissue (n = 2/14). Most bone tumors invaded surrounding soft tissue. Craniofacial bones were over-represented (n = 8/12). Median survival was 8 months and five patients are currently alive with a median follow-up of 20 months. Most tumors displayed a mixed spindle cell and epithelioid pattern with frequent vesicular nuclei. All tumors expressed keratins and showed a rhabdomyogenic phenotype (defined as expression of MYF4 and/or MYOD1). ALK was overexpressed in all but three cases without underlying ALK fusion on break-apart FISH (n = 5) nor next-generation sequencing (n = 14). ALK upregulation was frequently associated with an internal deletion at genomic level. TFCP2 was fused in 5' either to EWSR1 (n = 6) or FUS (n = 8). EWSR1 was involved in both soft tissue cases. FISH with TFCP2 break-apart probe was positive in all tested cases (n = 8), including one case with unbalanced signal. On array-CGH, all tested tumors displayed complex genetic profiles with genomic indexes ranging from 13 to 107.55 and recurrent CDKN2A deletions. FET-TFCP2 rhabdomyosarcomas clustered together and distinctly from other rhabdomyosarcomas subgroups. Altogether, our data confirm and expand the spectrum of the new family of FET-TFCP2 rhabdomyosarcomas, which are associated with a predilection for the craniofacial bones, an aggressive course, and recurrent pathological features. Their association with ALK overexpression might represent a therapeutic vulnerability.

Denosumab-treated Giant Cell Tumors of Bone: A Clinicopathologic Analysis of 35 Cases From the French Group of Bone Pathology.

Denosumab, an antibody directed against receptor activator of nuclear factor-κB ligand (RANKL), has recently been introduced in the treatment strategy of giant cell tumor of bone. In this study, we assessed the tumor changes induced by denosumab in a national multicentric series of 35 cases (French Bone Pathology Group network-ResOs). Tissue specimens collected before and after denosumab treatment were investigated for RANKL, H3.3 G34W, p63, and Ki-67 expression, and for H3F3A mutation. These parameters were put in correspondance with clinical and radiologic presentation to identify prognostic factors, and more specifically, predictive markers of an optimal histologic response to denosumab, identified as a ≥50% loss in giant cells with fibrosis and ossification. The main changes in posttreatment specimens showed an induction of ossification (P=2.10), an increased fibrosis (P=3.10), and a major decrease in giant cells (P=6.10). No significant change in mononuclear tumor cell density and in patterns of expression of RANKL (P=0.061) and H3.3 G34W was observed (P=0.061). An optimal histologic response to denosumab treatment was associated with an enhanced progression-free survival (P=0.010 in univariate analyses; P=0.040 in multivariate analyses). The initial number of giant cells was predictive of the histologic response to treatment (P=0.016). In summary, denosumab treatment induced radical changes in the tumor. The histologic response, despite the absence of objective regression of the mononuclear cells, was associated with an enhanced progression-free survival. Greater numbers of giant cells represented the only predictive indication of an optimal histologic response to denosumab treatment.

[Histological diagnosis of bone tumors: Guidelines of the French committee of bone pathologists reference network on bone tumors (RESOS)]. / Diagnostic histologique des tumeurs osseuses : biopsie chirurgicale ou biopsie percutanée ? Recommandations des pathologistes du réseau de référence des tumeurs osseuses (RESOS).

The management of patients having a bone lesion requires in many cases the realization of a histological sample in order to obtain a diagnosis. However, with the technological evolution, CT-guided biopsies are performed more frequently, often in outpatient clinics. Interpretation of these biopsies constitutes new challenges for the pathologists within the wide spectrum of bone entities. The purpose of the document is to propose guidelines based on the experience of the French committee of bone pathologists of the reference network on bone tumors (RESOS) regarding the indications and limitations of the diagnosis on restricted material.

[Benign and malignant giant-cell rich lesions of bone: Pathological diagnosis with special emphasis on recent immunohistochemistry and molecular techniques]. / Diagnostic des lésions osseuses riches en cellules géantes : démarche diagnostique et intérêt des nouvelles techniques complémentaires immuno-histochimiques et moléculaires.

The infiltration by numerous osteoclastic giant cells is a frequent finding in bone tumors and pseudo-tumors. Pathologists must integrate clinical and radiological data to achieve a correct diagnosis in bone pathology. Benign giant-cell rich lesions of bone encompass giant cell tumor of bone, aneurysmal bone cyst, chondroblastoma, brown tumor and fibrous cortical defect/non-ossifying fibroma. Amongst malignant neoplasms, variants of conventional osteosarcoma, undifferentiated pleomorphic sarcoma, leiomyosarcoma and bone metastasis must be discussed. Recently, new diagnostic markers, antibodies for immuno-histochemistry and genetic markers, have been developed and are helpful to diagnose such lesions.

Metastatic tumors to the colon and rectum: a multi-institutional study.

CONTEXT: Unlike the small bowel, the colorectal mucosa is seldom the site of metastatic disease. Objective.-To determine the incidence of truly colorectal metastases, and subsequent clinicopathologic findings, in a substantial colorectal cancer population collected from 7 European centers. DESIGN: During the last decade, 10 365 patients were identified as having colorectal malignant tumors, other than systemic diseases. Data collected included patient demographics, clinical symptoms, treatment, the presence of metastases in other sites, disease-free interval, follow-up, and overall survival. All secondary tumors resulting from direct invasion from malignant tumors of the contiguous organs were excluded, as well as those resulting from lymph node metastases or peritoneal seeding. RESULTS: Only 35 patients were included (10 men) with a median age of 59 years. They presented with obstruction, bleeding, abdominal pain, or perforation. The leading source of metastases was the breast, followed by melanoma. Metastases were synchronous in 3 cases. The mean disease-free interval for the remaining cases was 6.61 years. Surgical resection was performed in 28 cases. Follow-up was available for 26 patients; all had died, with a mean survival time of 10.67 months (range, 1-41 months). CONCLUSIONS: Colorectal metastases are exceptional (0.338%) with the breast as a leading source of metastases; they still represent a late stage of disease and reflect a poor prognosis. Therefore, the pathologist should be alert for the possibility of secondary tumors when studying large bowel biopsies. Any therapy is usually palliative, but our results suggest that prolonged survival after surgery and complementary therapy can be obtained in some patients.

Contribution of multimodality imaging for positive and aetiological diagnosis of multiple brown tumours.

This report concerns a rare case of multiple brown tumours discovered in a setting of primary hyperparathyroidism in a 64-year-old patient presenting with weight loss and leg pain. Biological, radiological and pathological findings led to the diagnosis of brown tumours. The contribution of anatomic and nuclear imaging techniques to the diagnosis of brown tumours and their aetiological assessment as well as pre-surgery localisation of parathyroid adenomas in the context of primary hyperparathyroidism is discussed.

[Place of the pathologist in the management of primary bone tumors (osteosarcoma and Ewing's family tumors after neoadjuvant treatment)]. / Rôle du pathologiste dans la prise en charge des tumeurs osseuses primitives malignes : ostéosarcomes et tumeurs de la famille Ewing après traitement néoadjuvant.

The survival of osteosarcoma and Ewing family tumours has been improved by the introduction of neoadjuvant chemotherapy. The response to preoperative chemotherapy is evaluated on the microscopic analysis of the surgical resection, by the percentage of tumour necrosis according to the Huvos and Rosen's grading. It remains the only reliable prognostic factor for patients and is used to guide the choice of post-operative chemotherapy. The macroscopic and microscopic management of the surgical resection (cf. supra) is essential and is the subject of a specific protocol. Several studies have been conducted to identify news factors able to predict the response to chemotherapy, the tumour aggressiveness and its ability to develop metastases. Inhibitors of mTOR and/or regulators of the balance RANKL/OPG are promising therapeutics. The study's expression of these new factors could be performed on the biopsy and will offer new therapeutic strategy.

Is Endoscopic Submucosal Dissection the Option for Early Gastric Cancer Patients with Contraindication to Surgery?

Surgical therapy is the traditional approach for early gastric cancer. Patients with comorbidities cannot benefit from this treatment because of high surgical morbidities and mortalities. Endoscopic submucosal dissection is a new technique for complete en bloc resection of early gastric cancer. We report the case of a patient with severe cardiomyopathy who developed early gastric cancer without metastases present on CT scan. The patient underwent endoscopic submucosal dissection because of the high risk associated to surgery due to severe comorbidity. The patient had complete submucosal dissection with complete en bloc resection. The lateral and deep margins were free of cancerous cells based on histopathology study. The patient was controlled every 6 months for 30 months by endoscopy. Systematic biopsies were done. No recurrences were diagnosed. This report supports the application of endoscopic treatment for patients with early gastric cancer and at high risk for surgery due to comorbidities.

Gene expression profiling provides insights into the pathways involved in solid pseudopapillary neoplasm of the pancreas.

Solid-pseudopapillary neoplasms (SPNs) are rare human pancreatic neoplasms usually associated with a good prognosis. In contrast to other pancreatic tumours, aberrant activation of the Wnt-beta-catenin pathway appears to be a constant feature in SPN. Aside from activation of the Wnt-beta-catenin pathway, little is known about biological pathways deregulated in SPN. We carried out transcriptome profiling of SPN to gain insights into the pathogenesis of these tumours. As expected, the over-expression of AXIN2, TBX3, SP5 and NOTUM demonstrated activation of the beta-catenin pathway. Members of the Notch pathway (HEY1, HEY2, NOTCH2) were also up-regulated, relative to their expression in ductal adenocarcinomas (DAC) or pancreatic endocrine tumours (PET). Other genes, such as EDN3, HAND2, netrin-G2 and the receptor netrin-G1 ligand, involved in neural crest differentiation, were also identified as altered. Increased levels of SOX10 and TuJ-1 proteins were also indicative of neural-like differentiation. In conclusion, SPN display a complex expression profile, distinct from that observed in PET and DAC and involving both the beta-catenin and Notch pathways, together with expression of neural differentiation markers.

Wnt/beta-catenin pathway in hepatocellular carcinoma pathogenesis and liver physiology.

The Wnt/beta-catenin pathway is a key developmental pathway for which alterations have been described in various human cancers. The aberrant activation of this pathway is a major event in human hepatocellular carcinoma. Several laboratories have shown that the Wnt/beta-catenin pathway plays an essential role in all phases of liver development and maturation, and is required for the metabolic function of this organ. In this review, we summarize current knowledge regarding the role of the Wnt/beta-catenin pathway in hepatocellular carcinoma pathogenesis and liver biology, and the possibilities for developing new therapeutic interventions based on this knowledge.

Impaired E-cadherin expression and glutamine synthetase overexpression in solid pseudopapillary neoplasm of the pancreas.

OBJECTIVES: To analyze in solid pseudopapillary neoplasm of the pancreas (SPNP) the consequences of the deregulated Wnt pathway by studying the expression of Wnt target glutamine synthetase (GLUL), cyclin D1, and E-cadherin, which is one of the beta-catenin binding partner in cell adhesion. METHODS: The expression of cyclin D1 and GLUL was studied at the protein and/or messenger RNA levels, and the immunolocalization for E-cadherin was analyzed in 28 SPNPs screened for beta-catenin mutations. Expression of cyclin D1, GLUL, and beta-catenin was also assessed in pancreatic endocrine tumors as controls. RESULTS: Cytosolic and/or nuclear accumulation of beta-catenin was observed in all tumors; an activating beta-catenin mutation was identified in 21 (91%) of 23 tumors analyzed. E-cadherin expression is lost from the membrane and is observed in intracytosolic "dotlike" structures. Whereas cyclin D1 expression is observed widely in SPNP and endocrine tumors, GLUL expression is restricted to SPNP (100%) and rare endocrine tumors (10%) displaying Wnt activation. CONCLUSIONS: The activation of the Wnt/beta-catenin pathway in SPNP has 2 main consequences. First, E-cadherin expression moved from membranous to intracytoplasmic localization. Second, GLUL expression is highly correlated with Wnt/beta-catenin activation, demonstrating its faithfulness as a Wnt target gene.

Rapid identification of promoter hypermethylation in hepatocellular carcinoma by pyrosequencing of etiologically homogeneous sample pools.

Aberrant DNA methylation patterns have been identified in a variety of human diseases, particularly cancer. Pyrosequencing has evolved in recent years as a sensitive and accurate method for the analysis and quantification of the degree of DNA methylation in specific target regions. However, the number of candidate genes that can be analyzed in clinical specimens is often restricted by the limited amount of sample available. Here, we present a novel screening approach that enables the rapid identification of differentially methylated regions such as promoters by pyrosequencing of etiologically homogeneous sample pools after bisulfite treatment. We exemplify its use by the analysis of five genes (CDKN2A, GSTP1, MLH1, IGF2, and CTNNB1) involved in the pathogenesis of human hepatocellular carcinoma using pools stratified for different parameters of clinical importance. Results were confirmed by the individual analysis of the samples. The screening identified all genes displaying differential methylation successfully, and no false positives occurred. Quantitative comparison of the pools and the samples in the pool analyzed individually showed a deviation of approximately 1.5%, making the method ideally suited for the identification of diagnostic markers based on DNA methylation while saving precious DNA material.

Multiplex target protein imaging in tissue sections by mass spectrometry--TAMSIM.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) is becoming a popular tool for imaging histological sections. Currently, this technology is used to image naturally occurring molecules. Here we report a novel development for multiplex imaging of candidate proteins. Rather than detecting whatever molecules happen to be present and above the detection threshold in the desorption pixel, we attach photocleavable mass tags to antibodies to target proteins. 'Staining' of histological sections is carried out similarly to common immunohistochemical procedures with chemiluminescent or fluorescent detection using all antibodies of a multiplex simultaneously. Mass tags with discrete masses are released from their respective antibodies by a laser pulse at 355 nm without added matrix. After scanning, mass spectrometry images are created for the mass of each tag. In contrast to fluorescent tags, mass tags do not exhibit mutual quenching. Sections of healthy human pancreatic tissue were imaged to visualize synaptophysin in neuroendocrine cells, and sections from human lymph node and liver invaded by metastatic melanoma to localize the cancer markers PS100 and HMB45 simultaneously. All these proteins are below the detection threshold of direct MALDI-MS imaging. This method is termed TAMSIM for TArgeted multiplex Mass Spectrometry IMaging.