Abstract
Purpose :
Ocular tuberculosis (OTB) remains a presumptive clinical diagnosis based on indicative ophthalmic features and prior exposure to TB. Ocular sampling is often unhelpful, so the diagnosis is supported by evidence of subclinical TB remote to the eye and response to anti-tuberculous therapy (ATT). We performed a retrospective, observational, clinical study of 50 patients presenting with OTB over a 5-year period, to test the hypotheses that different clinical phenotypes of OTB vary in their response to treatment and that fluorodeoxyglucose positron emission tomography (FDG-PET) assists in the detection of subclinical TB
Methods :
Patients were screened with a chest X-ray (CXR) and interferon gamma release assay (IGRA), with or without Tuberculin Skin Test (TST). Those with lymphadenopathy on CXR had a thoracic CT scan prior to endobronchial sampling. Where CXR (+/- thoracic CT) was normal, an FDG-PET scan was performed to look for activity in thoracic or extra-thoracic lymph nodes. ATT for 6, 9 or 12 months was supplemented with topical, peri-ocular, intra-ocular or systemic immunosuppression, as clinically indicated, and patients followed up for at least one year
Results :
Patients were mostly migrants to the UK, with no constitutional or respiratory symptoms. 95% had positive IGRA (+/- TST) results. Ocular pathology was bilateral in 50%. OTB with retino-choroidal involvement - retinal vasculitis (9) or choroiditis (12) - responded well to ATT and steroids, becoming burnt-out and quiescent. OTB with predominantly intermediate uveitis (15) or panuveitis (12) was more insidious, requiring chronic or recurrent management of vitritis or cystoid macular oedema post-ATT
FDG-PET scans in 22 patients demonstrated avid nodes in 14: thoracic in 9 and extra-thoracic in 8. FDG-PET directed additional endobronchial sampling in 5 patients with normal-sized nodes on thoracic CT and ultrasound-guided biopsy of extra-thoracic sites in 8 patients
Conclusions :
We describe a highly phenotyped cohort of OTB patients, with phenotypic subsets differing in their response to ATT and requirement for immunosuppression post-ATT. Whilst OTB treatment remains empirical in many cases, our results indicate that FDG-PET provides an additional diagnostic yield in subclinical TB over thoracic CT, allowing activity to be detected in normal-sized thoracic nodes and additional extra-thoracic sites
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.