Thyroid incidentalomas on PET imaging--evaluation of management and clinical outcomes.

OBJECTIVES: 1. To determine the incidence of 'thyroid incidentaloma' in patients undergoing PET/CT in Sheffield. 2. To assess the distribution of cancer type, stage and short term outcomes of incidentally detected thyroid cancer in this cohort. METHODOLOGY: Patients with an unexpected thyroid radio-isotope uptake on reports of whole body nuclear imaging performed in Sheffield Teaching Hospitals NHS Foundation Trust for 'non-thyroid' indications from April 2008 to March 2011 were identified. Patients who have undergone PET imaging were then selected. The management, clinical and pathology details and short term 'thyroid-related' outcomes of patients with thyroid incidentaloma on PET scans were analysed. RESULTS: 1730 PET nuclear imaging studies were performed in this period. Thyroid incidentalomas were detected in 65 (3.8%)of these scans. Two thyroid cancers were detected in this cohort, both demonstrated focal uptake on the PET scan. Histology showed papillary thyroid cancer (TNM classification; pT1N1Mx and pT1bNxMx). CONCLUSION: The risk of cancer in PET detected thyroid incidentaloma in this series (3%) is low compared to published literature (5-50%). Potential reasons are discussed. The low rate of thyroid cancer in our incidentaloma cohort will influence decision making regarding management of these lesions. Only two thyroid cancers were detected in our cohort, limiting the narrative on type, stage of PET detected thyroid cancer and outcomes. Further observational research is required to study the natural history of these lesions in settings where there is a clear protocol for imaging, biopsy and treatment.

False-negative rate of gram-stain microscopy for diagnosis of septic arthritis: suggestions for improvement.

We quantify the false-negative diagnostic rate of septic arthritis using Gram-stain microscopy of synovial fluid and compare this to values reported in the peer-reviewed literature. We propose a method of improving the diagnostic value of Gram-stain microscopy using Lithium Heparin containers that prevent synovial fluid coagulation. Retrospective study of the Manchester Royal Infirmary microbiology database of patients undergoing synovial fluid Gram-stain and culture between December 2003 and March 2012 was undertaken. The initial cohort of 1896 synovial fluid analyses for suspected septic arthritis was reduced to 143 after exclusion criteria were applied. Analysis of our Gram-stain microscopy yielded 111 false-negative results from a cohort size of 143 positive synovial fluid cultures, giving a false-negative rate of 78%. We report a false-negative rate of Gram-stain microscopy for septic arthritis of 78%. Clinicians should therefore avoid the investigation until a statistically significant data set confirms its efficacy. The investigation's value could be improved by using Lithium Heparin containers to collect homogenous synovial fluid samples. Ongoing research aims to establish how much this could reduce the false-negative rate.