Magnetic Resonance Imaging Features and Prognostic Indicators of Local Recurrence after Curettage and Cementation of Atypical Cartilaginous Tumour in the Appendicular Skeleton

Objective: The aim of this study is to determine MRI features that may be prognostic indicators of local recurrence (LR) in patients treated with curettage and cementation of atypical cartilaginous tumours (ACTs) in the appendicular skeleton. Materials and Methods: This study is a retrospective review of adult patients with histologically confirmed appendicular ACT. The data collected included age, sex, skeletal location and histology from curettage, the presence of LR and oncological outcomes. The pre-operative MRI characteristics of the ACT reviewed by a specialist MSK radiologist included lesion location, lesion length, degree of medullary filling, bone expansion, cortical status and the presence of soft tissue extension. Results: A total of 43 patients were included, including 9 males and 34 females with a mean age of 42.8 years (range: 25-76 years). Tumours were located in the femur (n = 19), humerus (n = 15), tibia (n = 5), fibula (n = 2) and radius and ulna (n = 1 each). A total of 19 lesions were located in the diaphysis, 12 in the metadiaphysis, 6 in the metaphysis and 6 in the epiphysis. The mean tumour length was 61.0 mm (range: 12-134 mm). The mean follow up was 97.7 months (range: 20-157 months), during which 10 (23.3%) patients developed LR, 7 (70%) of which were asymptomatic and 3 (30%) of which presented with pain. Four patients required repeat surgery with no associated death or evidence of metastatic disease. LR was significantly commoner with tumours arising in the epiphysis or metadiaphysis, but no MRI features were predictive of LR. Conclusions: No relationship was found between the apparent 'aggressiveness' of an ACT of the appendicular skeleton on MRI and the development of LR following treatment with curettage and cementation.

Evaluation of a new cytotoxicity assay for Clostridium perfringens type D epsilon toxin

A new cytotoxicity assay for determining the activity of epsilon toxin produced by Clostridium perfringens type D has been developed. Viability of cultured cells was determined by the ability of only live cells to convert 5-(3-carboxymethoxyphenyl)-2-(4,5-dimethylthiazolyl)-3-(4- sulfophenyl)tetrazolium to the coloured product formazan in the presence of phenazine methosulfate. Of the 12 cell lines tested, only the MDCK cell line was susceptible to epsilon toxin. Specificity was confirmed by the ability of only specific monoclonal antibodies to inhibit cytotoxicity. Good correlation was obtained with the mouse lethality assay (r = 0.991) and over a wide range of viability (15-75%) as determined by ethidium bromide/acridine orange staining (r = 0.995).