An unusual case of nodular fasciitis presenting as an intra-tendinous mass.

Nodular fasciitis is a benign soft tissue pseudotumour typically occurring in the upper extremities, head and neck, thigh and trunk. It is most commonly seen in subcutaneous locations but also can be present in intramuscular and intermuscular (fascial) locations. Its occurrence in the hand is rare, and while it can occur in close proximity to tendons, its presentation as an intra-tendinous mass has not been previously described. We present a unique and rare case of nodular fasciitis arising within the flexor digitorum profundus (FDP) tendon of the hand in a 16-year-old female. The patient presented with a painful swelling in the volar aspect of the base of her left middle finger, with progressive flexion deformity of the finger. Ultrasound and magnetic resonance imaging revealed a mass within the FDP tendon of the middle finger. An ultrasound-guided biopsy revealed a diagnosis of nodular fasciitis. Given the self-limiting nature of the condition, she was managed conservatively with close clinical and imaging follow-up. This case highlights the importance of considering nodular fasciitis in the differential diagnosis of an intra-tendinous lesion in the hand, even though it is a rare occurrence in this location. The clinical presentation, diagnostic workup, and management of this unique case are discussed, emphasising the potential for its misdiagnosis as a malignancy which can have important implications in management.

FGF23 Expression Is a Promising Immunohistochemical Diagnostic Marker for Undifferentiated Pleomorphic Sarcoma of Bone (UPSb).

Background: Undifferentiated pleomorphic sarcoma of bone (UPSb) is a rare primary bone sarcoma that lacks a specific line of differentiation. Distinguishing between UPSb and other malignant bone sarcomas, including dedifferentiated chondrosarcoma and osteosarcoma, is challenging due to their overlapping features. We have previously identified that UPSb tumours have elevated mRNA levels of Fibroblast Growth Factor 23 (FGF23) transcripts compared to other sarcomas including osteosarcoma. In the present study, we evaluated the specificity and practicality of FGF23 immunoreactivity as a specific diagnostic tool to differentiate UPSb tumours from osteosarcomas and dedifferentiated chondrosarcomas. Methods: A total of 10 UPSb, 10 osteosarcoma, and 10 dedifferentiated chondrosarcoma cases (all high-grade), were retrieved and immunohistochemistry for FGF23 was performed. Results: FGF23 protein was expressed at high levels in 80-90% of undifferentiated pleomorphic sarcoma of the bone cases, whereas it was expressed at significantly lower levels in dedifferentiated chondrosarcoma and osteosarcoma cases. A semiquantitative analysis, considering the intensity of immunoreactivity, confirmed significantly elevated FGF23 expression levels in UPSb tissues compared to those observed in osteosarcoma and dedifferentiated chondrosarcoma tissues. Conclusions: The results we present here suggest that FGF23 immunohistochemistry may be a useful tool to aid in differentiating UPSb from morphologically similar malignant bone sarcomas, especially in situations where sampling is restricted and there is limited clinical information available.

Small cell osteosarcoma versus fusion-driven round cell sarcomas of bone: retrospective clinical, radiological, pathological, and (epi)genetic comparison with clinical implications.

Small cell osteosarcoma (SCOS), a variant of conventional high-grade osteosarcoma (COS), may mimic fusion-driven round cell sarcomas (FDRCS) by overlapping clinico-radiological and histomorphological/immunohistochemical characteristics, hampering accurate diagnosis and consequently proper therapy. We retrospectively analyzed decalcified formalin-fixed paraffin-embedded (FFPE) samples of 18 bone tumors primarily diagnosed as SCOS by methylation profiling, fusion gene analysis, and immunohistochemistry.In eight cases, the diagnosis of SCOS was maintained, and in 10 cases it was changed into FDRCS, including three Ewing sarcomas (EWSR1::FLI1 in two cases and no identified fusion gene in the third case), two sarcomas with BCOR alterations (KMT2D::BCOR, CCNB3::BCOR, respectively), three mesenchymal chondrosarcomas (HEY1::NCOA2 in two cases and one case with insufficient RNA quality), and two sclerosing epithelioid fibrosarcomas (FUS::CREBL3 and EWSR1 rearrangement, respectively).Histologically, SCOS usually possessed more pleomorphic cells in contrast to the FDRCS showing mainly monomorphic cellular features. However, osteoid was seen in the latter tumors as well, often associated with slight pleomorphism. Also, the immunohistochemical profile (CD99, SATB2, and BCOR) overlapped.Clinically and radiologically, similarities between SCOS and FDRCS were observed, with by imaging only minimal presence or lack of (mineralized) osteoid in most of the SCOSs.In conclusion, discrimination of SCOS, epigenetically related to COS, versus FDRCS of bone can be challenging but is important due to different biology and therefore therapeutic strategies. Methylation profiling is a reliable and robust diagnostic test especially on decalcified FFPE material. Subsequent fusion gene analysis and/or use of specific immunohistochemical surrogate markers can be used to substantiate the diagnosis.

Chondrosarcoma of the Femur: Is Local Recurrence Influenced by the Presence of an Extraosseous Component?

BACKGROUND: Chondrosarcoma (CS) is the second most common surgically treated primary malignancy of the bone. The current study explored the effect of the margin and extraosseous tumor component in CS in the femur on local recurrence (LR), LR-free survival (LRFS), and disease-specific survival (DSS). METHODS: Among 202 patients, 115 were in the proximal extremity of the femur, 4 in the corpus of the femur, and 83 in the distal extremity of femur; 105 patients had an extraosseous tumor component. RESULTS: In the Kaplan-Meier analysis, factors significant for decreased LRFS were the extraosseous tumor component (p < 0.001), extraosseous tumor component arising from the superior aspect (p < 0.001), histological grade (p = 0.031), and narrow surgical margin < 3 mm (p < 0.001). Factors significantly affecting DSS were the histological grade (p < 0.001), extraosseous component (p < 0.001), LR (p < 0.001), metastases (p < 0.001), and surgical margin (p < 0.001). CONCLUSIONS: In CS of the femur, the presence of an extraosseous tumor component has a predictive role in LRFS, and extraosseous tumor component arising from the superior aspect was significant for decreased LRFS. Wide margins were more commonly achieved when the tumor had only an intraosseous component, and the rate of LR was significantly higher in cases with an extraosseous tumor component. When the extraosseous component arose from the superior aspect of the femur, LR occurred more frequently despite achieving adequate margins.

Bone metastases from chondroblastoma: a rare pattern of metastatic disease in an adult.

Chondroblastoma is a rare benign tumor, typically presenting in the first two decades. Systemic metastases in chondroblastoma are extremely rare and it is the rarity of these metastases which lead the World Health Organisation to re-classify this lesion from "intermediate" to "benign" in its updated classification of bone tumors in 2020. We present an unusual case of a 55 year-old male patient who presented with multiple FDG-avid bone lesions on a background of conventional chondroblastoma of the rib excised at another institution 11-years previously. Two of these lesions were also histologically-proven as conventional chondroblastoma at biopsy. This case highlights that, although rare, metastases can be seen in patients with chondroblastoma. To our knowledge, this is the only case with an unusual pattern of metastases limited to bone.

Disruption of the TP53 locus in osteosarcoma leads to TP53 promoter gene fusions and restoration of parts of the TP53 signalling pathway.

TP53 is the most frequently mutated gene in human cancer. This gene shows not only loss-of-function mutations but also recurrent missense mutations with gain-of-function activity. We have studied the primary bone malignancy osteosarcoma, which harbours one of the most rearranged genomes of all cancers. This is odd since it primarily affects children and adolescents who have not lived the long life thought necessary to accumulate massive numbers of mutations. In osteosarcoma, TP53 is often disrupted by structural variants. Here, we show through combined whole-genome and transcriptome analyses of 148 osteosarcomas that TP53 structural variants commonly result in loss of coding parts of the gene while simultaneously preserving and relocating the promoter region. The transferred TP53 promoter region is fused to genes previously implicated in cancer development. Paradoxically, these erroneously upregulated genes are significantly associated with the TP53 signalling pathway itself. This suggests that while the classical tumour suppressor activities of TP53 are lost, certain parts of the TP53 signalling pathway that are necessary for cancer cell survival and proliferation are retained. In line with this, our data suggest that transposition of the TP53 promoter is an early event that allows for a new normal state of genome-wide rearrangements in osteosarcoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

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.

Chondrosarcoma of the Proximal Humerus: Does the Margin Affect Survival?

Chondrosarcoma (CS) is the second most common primary malignant bone tumour and, in the absence of reliable chemotherapy and radiotherapy, is effectively a surgical disease. Overall disease specific survival (DSS) is affected by tumour grade, whilst resection margin contributes to local recurrence free survival (LRFS). The aim of this study was to investigate factors that affect the local and systemic prognoses for conventional central CSs arising from the proximal humerus. A multi-centre, retrospective study from three international collaborative sarcoma centres identified 110 patients between 1995 and 2020 undergoing treatment for a conventional central CS of the proximal humerus; 58 patients (53%) had a grade 1 tumour, 36 (33%) had a grade 2 tumour, and 16 patients (13%) had a grade 3 CS. The mean age of patients was 50 years (range 10-85). The incidence of local recurrence (LR) was 9/110 (8.2%), and the disease specific mortality was 6/110 (5.5%). The grade was a statistically significant factor for LRFS (p < 0.001). None of the grade 1 tumours developed LR. The DSS was affected by the grade (p < 0.001) but not by the LR (p = 0.4). Only one patient with a grade 2 tumour died from the disease. The proximal humeral grade 1 CS behaved as a benign tumour, having no cases of LR nor death due to disease. Grade 2 CSs of the proximal humerus behaved in a more indolent way when compared with comparable grade tumours elsewhere in the appendicular skeleton, being locally aggressive with a higher LR rate than grade 1 CSs but still having very low mortality and a high rate of DSS. The LR in grade 2 CSs did not affect the DSS; therefore, surgical management in proximal humeral grade 2 CSs should have a greater emphasis on preserving function whilst maintaining an adequate margin for resection. The proximal humeral grade 3 CS was, as elsewhere in the skeleton, an aggressive, high-grade tumour. Therefore, surgical management should include en bloc resection with clear margins to avoid LR.

Secondary Chondrosarcoma Arising in Synovial Chondromatosis of Wrist Joint.

Introduction: Chondrosarcoma of the synovium is a rare and malignant form of cartilaginous tumor that originates in synovial tissue. There have only been a limited number of reported cases of malignant transformation of synovial chondromatosis (SC) into secondary chondrosarcoma (SCH), primarily in the hip and knee, in patients with resistant illness. The occurrence of chondrosarcoma in SC of the wrist is highly uncommon, as evidenced by only a single previous case study that has been documented in the literature. Case Report: This study presents a case series of two patients with primary SC who developed SCH at the wrist joint. Conclusion: Clinicians treating localized swellings of the hand and wrist should be alert to the likelihood of a sarcoma diagnosis to minimize delays to definitive therapy.

YBX1-interacting small RNAs and RUNX2 can be blocked in primary bone cancer using CADD522.

Primary bone cancer (PBC) comprises several subtypes each underpinned by distinctive genetic drivers. This driver diversity produces novel morphological features and clinical behaviour that serendipitously makes PBC an excellent metastasis model. Here, we report that some transfer RNA-derived small RNAs termed tRNA fragments (tRFs) perform as a constitutive tumour suppressor mechanism by blunting a potential pro-metastatic protein-RNA interaction. This mechanism is reduced in PBC progression with a gradual loss of tRNAGlyTCC cleavage into 5' end tRF-GlyTCC when comparing low-grade, intermediate-grade and high-grade patient tumours. We detected recurrent activation of miR-140 leading to upregulated RUNX2 expression in high-grade patient tumours. Both tRF-GlyTCC and RUNX2 share a sequence motif in their 3' ends that matches the YBX1 recognition site known to stabilise pro-metastatic mRNAs. Investigating some aspects of this interaction network, gain- and loss-of-function experiments using small RNA mimics and antisense LNAs, respectively, showed that ectopic tRF-GlyTCC reduced RUNX2 expression and dispersed 3D micromass architecture in vitro. iCLIP sequencing revealed YBX1 physical binding to the 3' UTR of RUNX2. The interaction between YBX1, tRF-GlyTCC and RUNX2 led to the development of the RUNX2 inhibitor CADD522 as a PBC treatment. CADD522 assessment in vitro revealed significant effects on PBC cell behaviour. In xenograft mouse models, CADD522 as a single agent without surgery significantly reduced tumour volume, increased overall and metastasis-free survival and reduced cancer-induced bone disease. Our results provide insight into PBC molecular abnormalities that have led to the identification of new targets and a new therapeutic.

The management of non-diagnostic soft tissue tumour biopsies using a multi-disciplinary team approach: A 10-year retrospective review at a specialist sarcoma unit.

Non-Diagnostic (ND) biopsies are occasionally encountered during the investigation of soft tissue sarcoma. We performed a retrospective review of all ND soft tissue biopsies discussed at our regional Multi-Disciplinary Team (MDT) meeting between 2004 & 2014 with the aim of establishing the incidence of ND biopsies, identifying predictive factors for repeat biopsies and evaluating the effectiveness of MDT decisions. We identified 80 ND out of 3233 biopsies. Diagnostic Yield (DY) was 97.5%, 76.0% and 77.8% for the first, second and third successive biopsy respectively. With an MDT approach utilising radiological and clinical information, the diagnostic success rate achieved was 98.5%, 82.0% and 77.8% for the first, second and third biopsies respectively. Malignant tumours (sarcoma & carcinoma) were 19 times more likely to undergo an increasing number of biopsies compared to benign lesions (p < 0.01), while repeat biopsies were less useful for suspected benign lesion. Although a repeat biopsy was only performed in 63% of cases, there were no patients originally diagnosed with a benign lesion that re-presented with the same lesion subsequently being malignant throughout the study period. Our study shows that a specialist MDT approach leads to high diagnostic rates and is a safe and effective method of preventing unnecessary, repeat biopsies where the initial biopsy is ND.

Haemorrhagic soft-tissue sarcoma: Oncological outcomes and prognostic factors for survival.

INTRODUCTION: Haemorrhagic soft-tissue sarcomas (HSTS) are characterised by aggressive local growth and highly metastatic behaviour. We aimed to describe oncological outcomes and prognostic factors. MATERIALS AND METHODS: Retrospective review including 64 patients treated with palliation (n = 7), with limb salvage surgery (LSS) (n = 9), with neoadjuvant radiotherapy (RT) + LSS (n = 12), with LSS + adjuvant RT (n = 30) or amputation (n = 6). Kaplan-Meier survival analysis estimated overall survival (OS), metastasis-free survival (MFS) and local recurrence-free survival (LRFS). After uni- and multivariate analysis, prognostic factors affecting OS, MFS and LRFS were identified. RESULTS: Median age was 67 years (IQR 23 years) with median follow-up of 11 months (IQR 28 months). All cases were high grade. Eight (13%) had pulmonary metastases at presentation and another 40 (63%) developed metastases after median 9 months (IQR 19 months). Median OS was 12 months (IQR 38 months), and estimated OS after two-years was 15.9% and 52.9% for patients with and without metastatic disease at presentation, respectively. Improved OS was associated with negative resection margins (p = 0.031), RT (p = 0.045), neoadjuvant RT (versus adjuvant RT, p = 0.044) and amputation (versus LSS, p < 0.001). MFS was 35.1% after two-years. LR occurred in 18 of 51 (35.3%) patients with surgically treated localised disease. LRFS was 63.4% after two-years and significantly affected by a negative margin (p = 0.042) and RT (p = 0.001). CONCLUSION: Haemorrhagic soft-tissue sarcomas should be excised, either with amputation or LSS with a clear resection margin. If LSS is attempted, neoadjuvant RT reduces the risk of tumour spillage and early LR, enhances the feasibility of achieving clear resection margins, and offers superior overall survival compared to adjuvant RT.

Soft Tissue Sarcomas Mimicking Benign Inflammatory Processes: A Diagnostic Dilemma.

Background: Soft tissue sarcomas are rare and often go undetected until a later stage, particularly when they present as intra-articular or tenosynovial lesions mimicking benign synovial pathologies. The failure to distinguish between malignant and benign synovial disease can have a significant impact on patient outcomes and limit alternatives for local control surgery and limb salvage. Case Description: In this case series, we present two cases of soft tissue sarcomas, one being an intraarticular synovial chondrosarcoma, and the other a pleomorphic spindle cell sarcoma centred along tendon sheaths. Radiologically, the initial clinical presentation of these cases resembled benign synovial pathologies, leading to a delay in diagnosis and treatment. Conclusion: Our study underscores the importance of maintaining a low threshold of suspicion for surveillance, a multidisciplinary approach, and early histological diagnosis to ensure appropriate timely treatment and a favourable prognosis for patients with soft tissue sarcomas.

A Multidisciplinary Team Approach Is Highly Effective in the Management of Nondiagnostic Bone Tumour Biopsies: A 10-Year Retrospective Review at a Specialist Sarcoma Unit.

Nondiagnostic (ND) biopsies are frequently encountered during the investigation of bone tumours and can lead to treatment delay. We performed a retrospective review of all ND bone tumour biopsies discussed at our regional MDT meeting between 2004 and 2014 with the aim of establishing the incidence of ND biopsies, identifying any factors that could predict the requirement for repeat biopsies, and evaluating the effectiveness of multidisciplinary team (MDT) decisions. We identified 98 ND out of 4949 biopsies. Diagnostic yield (DY) was 98%, 76%, and 40% for the first, second, and third successive biopsy, respectively. With an MDT approach utilising radiological and clinical information, the diagnostic success rate achieved was 99%, 85%, and 80% for the first, second, and third biopsies, respectively. Although a repeat biopsy was only performed in 34% of cases, there were no patients originally diagnosed with a benign lesion that re-presented with the same lesion subsequently being malignant throughout the study period. Malignant primary bone tumours (p < 0.01) and malignant secondary tumours (p=0.02) were more likely to undergo repeat biopsy compared to benign and infective lesions. Upper limb (p=0.04) and lower limb (p=0.03) were more likely than pelvic and spinal tumours to undergo a repeat biopsy. Tumours of haematological origin frequently required multiple biopsies. Our study demonstrated that a specialist MDT approach leads to high diagnostic rates and is a safe and effective method of preventing unnecessary, repeat biopsies where the initial biopsy is ND.

Overlapping morphological, immunohistochemical and genetic features of superficial CD34-positive fibroblastic tumor and PRDM10-rearranged soft tissue tumor.

Superficial CD34-positive fibroblastic tumor (SCD34FT) is a recently recognized soft tissue tumor that is considered to be of borderline malignancy. The pathogenesis of this tumor remains incompletely understood, but it has been suggested that SCD34FT overlaps with tumors showing fusions involving the PRDM10 gene. Previous analyses of PRDM10-rearranged tumors have demonstrated that they have a distinct gene expression profile, resulting in high expression of CADM3 (also known as SynCam3), which can be detected immunohistochemically. Here, we investigated a series (n = 43) of SCD34FT or PRDM10-rearranged tumors and potential mimics (n = 226) with regard to morphological, genetic, and immunohistochemical features. The results show that SCD34FT and PRDM10-rearranged tumor are morphologically indistinguishable; 41 of 43 tumors of both entities are CADM3-positive. Hence, we suggest that they constitute a single entity, preferably referred to as SCD34FT. Expression of CADM3 was only rarely seen in other soft tissue tumors, except in tumors with Schwann cell differentiation. Thus, IHC for CADM3, in combination with the characteristic morphological features, is a valuable adjunct in the diagnosis of SCD34FT.

Carcinoma arising within sciatic nerve endometriosis: a case report.

Endometriosis is a common condition with significant morbidity. There have been case reports of endometrial deposits affecting the sciatic nerve. Sciatic nerve endometriosis presents with cyclical sciatica and is often difficult to diagnose as it mimics many other causes of sciatica. We report the first case of histological proven endometrial carcinoma arising in a pre-existing sciatic nerve endometriosis. This was initially managed with radiotherapy however symptoms persisted and she opted to have surgery with the aim of better symptom control and long-term prognosis.