The primary aim of this study was to compare the clinical outcomes of osteoid osteoma (OO) between the group of patients with the presence of nidus on biopsy samples from radiofrequency ablation (RFA) with those without nidus. Secondly, we aimed to examine other factors that may affect the outcomes of OO reflecting our experience as a tertiary orthopaedic oncology centre.

We retrospectively reviewed 88 consecutive patients diagnosed with OO treated with RFA between November 2005 and March 2015, consisting of 63 males (72%) and 25 females (28%). Sixty-six patients (75%) had nidus present in their biopsy samples. Patients’ mean age was 17.6 years (4-53). Median duration of follow-up was 12.5 months (6-20.8). Lesions were located in the appendicular skeleton in seventy-nine patients (90%) while nine patients (10%) had an OO in the axial skeleton. Outcomes assessed were based on patients’ pain alleviation (partial, complete, or no pain improvement) and the need for further interventions.

Pain improvement in the patient group with nidus in histology sample was significantly better than the group without nidus (OR 7.4, CI 1.35-41.4, p=0.021). The patient group with nidus on biopsy demonstrated less likelihood of having a repeat procedure compared to the group without nidus (OR 0.092, CI 0.016-0.542, p=0.008). Our study showed significantly better outcomes in pain improvement in appendicular lesions compared to the axially located lesions (p = 0.005). Patients with spinal lesions tend to have relatively poor pain relief than those with appendicular or pelvic lesions (p=0.007).

Patients with nidus on histology had better pain alleviation compared to patients without nidus. The histological presence of nidus significantly reduces the chance of repeat interventions. The pain alleviation of OO following RFA is better in patients with appendicular lesions than spinal or axially located lesions.

The use of routine sampling for histological analysis during revision hip replacement has been standard practice in our unit for many years. It is used to identify the presence of inflammatory processes that may represent peri-prosthetic infection.

This study follows up on a smaller study in the same unit in 2019 where an initial 152 cases were scrutinised. In this follow up study we examined 1,361 consecutive patients over a 16-year period whom had undergone revision hip replacement in a tertiary orthopaedic centre for any reason excluding primary bone tumour or malignant metastasis. All patients had tissue sampling for histopathological analysis performed by consultant histopathologists with a specialist interest in musculoskeletal pathology. The presence of bacteria in greater than 50% of samples sent for microbiological analysis in each patient was used as the gold standard diagnostic comparator for infection. This was then compared with the histology report for each patient.

After excluding 219 patients with incomplete data and 1 sample rejection, 1,141 cases were examined. Microbiology confirmed infection in 132 cases (prevalence of infection 11.04%) and histopathology analysis suggested infection in 171 cases. Only 64 cases with confirmed infection in more than 50% of microbiology samples had concurrent diagnosis of infection on histological analysis (5.60% of total; PPV 51.20%). Furthermore, microbiology analysis confirmed infection in 62 cases where histological analysis failed to identify infection (5.43% of total; False negative rate 49.21%). Overall, histopathology analysis was seen to have a good specificity of 93.99% but poor sensitivity of 50.79%.

We believe that this is the largest series in the literature and is somewhat unique in that all histology analysis was performed by consultant histopathologists with specialist interest in musculoskeletal pathology. Based on the costs incurred by this additional investigation our experience does not support routine sampling for histological analysis in revision hip arthroplasty. This is a substantial paradigm shift from current practice among revision arthroplasty surgeons in the United Kingdom but would equate to a substantial cost saving.

Osteosarcomas represent a heterogeneous group of primary bone tumours that affect predominantly the long bones of patients in the first two decades of life. We aim to describe the secondary effects of a poor response (⋋90% necrosis) to chemotherapy on the effectivity of other treatment outcomes, local recurrence and survival rates.

182 cases of osteosarcoma with necrosis of less than 90% and no metastases at diagnosis have been seen at our institution over 24 years. There were 60 amputations. 122 patients underwent limb salvage, with 105 marginal margins and 17 contaminated. There was no difference in size or location between the two groups. In the 122 patients with LSS, 21 had adjuvant radiotherapy and 101 did not. In the entirety of patients with ⋋90% necrosis, survival was 64% at 2 years and 37% at 5 years. When LSS Marginal resections were compared with amputation there was a significant (P=0.006) difference in survival. LSS with a marginal margin had a 25% risk of LR. In these patients there was 25% survival, whereas the absence of a local recurrence, conferred a benefit of a 40% survival XRT was used in 21 of the 122 who underwent limb salvage. The decision to use XRT was made by the local oncologist at the treating unit. There was a 24% rate of recurrence in the XRT group and 25% with no XRT.

These data demonstrated that patients who had a poor response to chemotherapy and underwent an amputation faired poorly when compared to patients with LSS. There is a selection bias in patients selected to undergo amputation. Additionally, patients who underwent amputation had a lower rate of local recurrence, but still had a poorer survival when compared to LSS.

Introduction

To look at the effect of width and tissue at surgical margins, together with the use of adjuvant therapy on locally recurrent disease and disease free survival.

Of 3000 patients diagnosed with primary malignant bone tumours and treated at our unit over the past 25 years, 234 (7.8%) were considered to be spindle cell sarcomas of bone (ie not osteosarcoma, chondrosarcoma, Ewing’s, chordoma or adamantinoma). We have analyzed their management and outcomes.

The diagnosis of these cases varied with fluctuations in the popularity of conditions such as MFH, fibrosarcoma and leiomyosarcoma with the passage of time. Treatment was with chemotherapy and surgery whenever possible. 36 patients had metastases at diagnosis and 17 had palliative treatment only because of age or infirmity. The most common site was the femur followed by the tibia, pelvis and humerus. The mean age was 45 and the mean tumour size 10.2cm at diagnosis. 25% of patients presented with a pathological fracture. Chemotherapy was used in 70% of patients the most common regime being cisplatin and doxorubicin. 35% of patients having neoadjuvant chemotherapy had a good (> 90% necrosis) response. The amputation rate was 22% and was higher in patients presenting with a fracture and in older patients not having chemotherapy.

With a mean follow up of 8 years the overall survival was 64% at 5 yrs and 58% at 10 yrs. Adverse prognostic factors included the need for amputation, older age and poor response to chemotherapy as well as a pathological fracture at presentation. The few patients with angiosarcoma fared badly but there was no difference in outcomes between patients with other diagnoses.

We conclude that patients with spindle cell sarcomas should be treated similarly to patients with osteosarcoma and can expect comparable outcomes. The histological diagnosis does not appear to predict behaviour.

Background: ASPS is a rare, high grade sarcoma primarily affecting children and young adults. Its origin remains enigmatic and there has until recently been no diagnostic markers. Diagnostic problems particularly occur when presenting as metastasis before detection of the primary tumour and when there is morphologic overlap with other malignancies. Recently, identification ASPS/TFE3 fusion transcripts and immuno-detection of TFE3 have been reported as useful diagnostic tools.

Design: 17 ASPS were analysed in terms of clinicopatho-logic characteristics, treatment and follow up. Archival formalin-fixed and paraffin embedded tissues were used for TFE3 immuno-histochemistry and RNA extraction followed by RT-PCR analysis and sequencing. Novel primers to detect ASPS/TFE3 fusion transcripts, type 1 and 2, were designed.

Results: The patients, 9 females/8 males, ranged in age from 3 to 46 years (median 23 years); 16 involved the extremities (9 lower, 7 upper) and one the pelvis. All but one patient had primary, curative surgery; chemotherapy and radiotherapy was given for metastatic disease. Five had lung metastases at diagnosis and 3 developed lung and brain metastases later. Four patients died of disease (after 1–5 years), 4 are alive with metastases and 9 are alive and well (after 6 mos.-10 years). 15/15 ASPS showed ASPL/TFE3 fusion transcripts (8 type 1, 7 type 2) and TFE3 immuno-positivity. Of 26 control tumours, several of which with overlapping morphologic features, none had fusion transcripts, 4 showed immuno-positivity (all granular cell tumours).

Conclusions: Immuno-detection of TFE3 and RT-PCR based identification of ASPL/TFE3 fusion transcripts in formalin-fixed/paraffin embedded tissues are powerful tools in the diagnosis of ASPS.

Introduction: Current practice in the UK is to perform clinical follow up on patients with soft tissue sarcoma (STS) and only to request cross sectional imaging if there is clinical suspicion. We aimed to assess the effectiveness of this policy by investigating the patients who developed a local recurrence (LR) after previous treatment for STS and whether the size and extent at diagnosis of LR affected their subsequent management

Method: We reviewed the clinical records and imaging of all patients with diagnosed LR of STS to investigate the site and size of the LR and its management.

Results: 35 patients were diagnosed with LR over a 3 year time period. The average time from previous definitive treatment was almost 19 months. The suspicion was made by the patient in 18 patients, by a doctor in 16 and a district nurse in 1. The patients had MRI to confirm the diagnosis followed by biopsy or excision biopsy. 31 of the tumours were high grade, 2 low and 2 were not excised. The size at time of LR was 5.6 cm (range 0.5–15). 12 of the patients had concomitant metastases. 16 were treated by local excision and 5 by amputation whilst 14 patients had palliation. It was felt that with earlier diagnosis the clinical management would have been different in:

those 7 whose LR was inoperable due to size,

Discussion: Earlier diagnosis could have led to simpler surgery in a third of the affected patients. This study raises the question as to whether a more aggressive policy of follow up with regular imaging (either MRI or ultrasound) could detect LR earlier and lead to improved outcomes.

Myxoid liposarcoma (MLS) is an unusual type of soft tissue sarcoma as it tends to metastasize frequently to sites other than the lungs. This study was aimed to investigate the natural history of patients with MLS to try and identify prognostic factors which could help predict outcome and aid earlier detection of metastases.

Data was prospectively collected from patient notes and analysed retrospectively. Prognostic factors and metastatic pattern were examined using Kaplan-Meier curves. There were 124 patients with MLS, aged between 28 and 93, the median size of the tumours was 12cm and the most common site was the thigh. Following treatment with excision and radiotherapy the 5yr survival was 65%. Survival was related to younger age (p=0.010) and proximal site (p=0.003) and was also related to the % round cell component of the tumour but was not related to either size or depth of the tumour. Site and margins of excision were significant prognostic factors for local recurrence of disease. 32% of patients developed metastases, of whom 18 cases (46.2%) developed pulmonary metastases and 21 (53.8%) developed extra pulmonary metastases. The sites of these varied hugely and was not significantly related to the site or size of the primary tumour. There was no difference in time to develop metastases or in overall survival between the two groups. Median survival following metastases was 24 months.

Although MLS has an unusual pattern of metastases the site of metastases does not predict a better or worse outcome. Intensive follow up for extraskeletal metastases is probably not justified until they become symptomatic.