Usefulness of (18)F-FDG PET/CT for evaluating response of ocular adnexal lymphoma to treatment

The purpose of this study was to investigate the efficacy of (18)F-fluoro-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for evaluating the ocular adnexal lymphoma treatment responses. We retrospectively reviewed data for 9 histologically confirmed cases of malignant lymphoma. All patients had at least one ocular adnexal tumor site and underwent FDG PET/CT before and after treatment. Patients’ histological disease subtypes included diffuse large B-cell lymphoma (n = 3), mucosa-associated lymphoid tissue lymphoma (n = 2), follicular lymphoma (n = 1), NK/T-cell lymphoma (n = 1), lymphoplasmacytic lymphoma (n = 1), and Hodgkin lymphoma (n = 1). The highest FDG uptake by the ocular adnexal lesions was calculated as the maximum standardized uptake value (SUVmax). FDG uptake at ocular adnexal sites and sites of systemic disease after treatment were also assessed using the 5-point Deauville scale. In 1 of the 9 patients, a conjunctival lesion could not be detected by either pre- or posttreatment PET/CT. For 8 of the 9 patients, the SUVmax value at the ocular adnexal site significantly decreased after treatment (7.1 ± 5.1 vs 1.6 ± 0.58; P = .0196). For 7 of the 9 patients, the first posttreatment FDG uptake at the ocular adnexal site was considered a complete metabolic response, and these patients showed an improved clinical ophthalmic presentation with no relapse at ocular adnexal sites during follow-up. FDG PET/CT is useful for evaluation of the response of ocular adnexal lymphoma to treatment, although its usefulness may depend on the histological subtype and site of the lesion.