Diagnostic Utility of IDH1/2 Mutations to Distinguish Dedifferentiated Chondrosarcoma from Undifferentiated Pleomorphic Sarcoma of Bone

Histologically it is nearly impossible to distinguish the dedifferentiated component of dedifferentiated chondrosarcoma from undifferentiated pleomorphic sarcoma of bone when the low-grade cartilaginous component is absent. Previous studies have revealed that isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations are present in a significant number of cartilaginous tumors including the majority of conventional chondrosarcoma and dedifferentiated chondrosarcomas. These mutations have not been studied in undifferentiated pleomorphic sarcomas of bone. We sought to investigate whether an IDH1 or IDH2 mutation signature could be used as a clinically diagnostic marker for the distinction of dedifferentiated component of chondrosarcoma from undifferentiated pleomorphic sarcoma of bone. Sixty-eight bone tumor cases, including 31 conventional chondrosarcomas, 23 dedifferentiated chondrosarcomas, and 14 undifferentiated pleomorphic sarcomas of bone, were collected for IDH1/2 mutation analysis either using the Qiagen IDH1/2 RGQ PCR Kit or using whole exome sequencing. IDH1/2 mutations were detected in 87% (20/23) of dedifferentiated chondrosarcomas and 30% (6/20) of conventional chondrosarcomas. No mutations were detected in the IDH1/2 codon 132 or codon 172 among 14 UPS of bone. Identification of IDH1 or IDH2 mutations supports the diagnosis of dedifferentiated chondrosarcoma rather than undifferentiated pleomorphic sarcoma of bone while also providing some insight into the pathogenesis of these two lesions

Subclassification of epithelioid sarcoma with potential therapeutic impact

Epithelioid sarcoma is a rare and aggressive mesenchymal tumour, the genetic hallmark of which is the loss of expression of SMARCB1, a key member of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodelling complex. Hampered by its rarity, epithelioid sarcoma has received little research attention and therapeutic options for this disease remain limited. SMARCB1-deficient tumours also include malignant rhabdoid tumour, atypical teratoid and rhabdoid tumour, epithelioid malignant peripheral nerve sheath tumour, and poorly differentiated chordoma. Histologically, it can be challenging to distinguish epithelioid sarcoma from malignant rhabdoid tumour and other SMARCB1-deficient tumours, whereas methylation profiling shows that they represent distinct entities and facilitates their classification. Methylation studies on SMARCB1-deficient tumours, although not including epithelioid sarcomas, reported methylation subgroups which resulted in new clinical stratification and therapeutic approaches. In addition, emerging evidence indicates that immunotherapy, including immune checkpoint inhibitors, represents a promising therapeutic strategy for SMARCB1-deficient tumours. Here, we show that some epithelioid sarcomas share methylation patterns of malignant rhabdoid tumours indicating that this could help to distinguish these entities and guide treatment. Using gene expression data, we also showed that the immune environment of epithelioid sarcoma is characterised by a predominance of CD8+ lymphocytes and M2 macrophages. These findings have potential implications for the management of patients with epithelioid sarcoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland

Lymphoid aggregates that resemble tertiary lymphoid organs define a specific pathological subset in metal-on-metal hip replacements

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) has been used to describe the histological lesion associated with metal-on-metal (M-M) bearings. We tested the hypothesis that the lymphoid aggregates, associated with ALVAL lesions resemble tertiary lymphoid organs (TLOs). Histopathological changes were examined in the periprosthetic tissue of 62 M-M hip replacements requiring revision surgery, with particular emphasis on the characteristics and pattern of the lymphocytic infiltrate. Immunofluorescence and immunohistochemistry were used to study the classical features of TLOs in cases where large organized lymphoid follicles were present. Synchrotron X-ray fluorescence (XRF) measurements were undertaken to detect localisation of implant derived ions/particles within the samples. Based on type of lymphocytic infiltrates, three different categories were recognised; diffuse aggregates (51%), T cell aggregates (20%), and organised lymphoid aggregates (29%). Further investigation of tissues with organised lymphoid aggregates showed that these tissues recapitulate many of the features of TLOs with T cells and B cells organised into discrete areas, the presence of follicular dendritic cells, acquisition of high endothelial venule like phenotype by blood vessels, expression of lymphoid chemokines and the presence of plasma cells. Co-localisation of implant-derived metals with lymphoid aggregates was observed. These findings suggest that in addition to the well described general foreign body reaction mediated by macrophages and a T cell mediated type IV hypersensitivity response, an under-recognized immunological reaction to metal wear debris involving B cells and the formation of tertiary lymphoid organs occurs in a distinct subset of patients with M-M implants

Targeting the MAPK7/MMP9 axis for metastasis in primary bone cancer

Metastasis is the leading cause of cancer related death. This multistage process involves contribution from both tumour cells and the tumour stroma to release metastatic cells into the circulation. Circulating tumour cells (CTCs) survive circulatory cytotoxicity, extravasate and colonise secondary sites effecting metastatic outcome. Reprogramming the transcriptomic landscape is a metastatic hallmark but detecting underlying master regulators that drive pathological gene expression is a key challenge, especially in childhood cancer. Here we used whole tumour plus single cell RNA sequencing in primary bone cancer and CTCs to perform weighted gene co-expression network analysis to systematically detect coordinated changes in metastatic transcript expression. This approach with comparisons applied to data collected from cell line models, clinical samples and xenograft mouse models revealed MAPK7/MMP9 signalling as a driver for primary bone cancer metastasis. RNAi knockdown of MAPK7 reduces proliferation, colony formation, migration, tumour growth, macrophage residency/polarisation and lung metastasis. Parallel to these observations were reduction of activated interleukins IL1B, IL6, IL8 plus mesenchymal markers VIM and VEGF in response to MAPK7 loss. Our results implicate a newly discovered, multidimensional MAPK7/MMP9 signalling hub in primary bone cancer metastasis that is clinically actionable

Miscellaneous Tumours of Bone.

There are several tumors that do not easily fit into the specific classifications of primary bone tumors. These tumors include tumors of neural, adipocytic, smooth muscle lineage, and some of uncertain lineage. The pathologic features with recent updates of these tumors are discussed here

Predictors of time to revision and clinical outcomes following revision of metal-on-metal hip replacements for adverse reaction to metal debris

We undertook a retrospective cohort study to determine clinical outcomes following the revision of metal-on-metal (MoM) hip replacements for adverse reaction to metal debris (ARMD), and to identify predictors of time to revision and outcomes following revision. Between 1998 and 2012 a total of 64 MoM hips (mean age at revision of 57.8 years; 46 (72%) female; 46 (72%) hip resurfacings and 18 (28%) total hip replacements) were revised for ARMD at one specialist centre. At a mean follow-up of 4.5 years (1.0 to 14.6) from revision for ARMD there were 13 hips (20.3%) with post-operative complications and eight (12.5%) requiring re-revision. The Kaplan–Meier five-year survival rate for ARMD revision was 87.9% (95% confidence interval 78.9 to 98.0; 19 hips at risk). Excluding re-revisions, the median absolute Oxford hip score (OHS) following ARMD revision using the percentage method (0% best outcome and 100% worst outcome) was 18.8% (interquartile range (IQR) 7.8% to 48.3%), which is equivalent to 39/48 (IQR 24.8/48 to 44.3/48) when using the modified OHS. Histopathological response did not affect time to revision for ARMD (p = 0.334) or the subsequent risk of re-revision (p = 0.879). Similarly, the presence or absence of a contralateral MoM hip bearing did not affect time to revision for ARMD (p = 0.066) or the subsequent risk of re-revision (p = 0.178). Patients revised to MoM bearings had higher rates of re-revision (five of 16 MoM hips re-revised; p = 0.046), but those not requiring re-revision had good functional results (median absolute OHS 14.6% or 41.0/48). Short-term morbidity following revision for ARMD was comparable with previous reports. Caution should be exercised when choosing bearing surfaces for ARMD revisions. Cite this article: Bone Joint J 2014;96-B:1600–9. </jats:p

Recurrent Fusions Between YAP1 and KMT2A in Morphologically Distinct Neoplasms Within the Spectrum of Low-grade Fibromyxoid Sarcoma and Sclerosing Epithelioid Fibrosarcoma

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Pre- and post-chemotherapy alkaline phosphatase levels as prognostic indicators in adults with localised osteosarcoma

The prognostic value of alkaline phosphatase (AP) measured before and after chemotherapy, but before surgery was established in a retrospective survey of patients. The patients were 18 years or older, with non-metastatic high-grade osteosarcoma. Pre-chemotherapy AP was available in 89 cases, post-chemotherapy AP in 86 patients, and both in 71 cases. AP was classified as Normal ( or = 200%). Osteosarcoma subtype was predominantly conventional. No correlation was found between subtype and chemotherapy response, local recurrence or survival. Pre-chemotherapy AP was raised more in the osteoblastic subtype. Post-chemotherapy AP and normalisation were the same among different subtypes. AP was not correlated with local recurrence. Normal or High pre-chemotherapy AP correlated with better survival at 10 years (64% and 70%) than Very High pre-chemotherapy AP (37%, P = 0.005). Post-chemotherapy AP correlated with survival (68%, 39% and 25% in the Normal, High and Very High group, P = 0.0007) and response to chemotherapy (P = 0.049). A pre-chemotherapy AP above twice Normal correlated with worse survival. If AP decreased after chemotherapy, but was still raised, survival was better, but still worse than if AP normalised. A raised post-chemotherapy AP predicts poor chemotherapy respons