Value of 18FDG PET scan in staging of ocular adnexal lymphomas: a large single-center experience

Fluorine 18 deoxyglucose positron emission tomography ((18)FDG PET) is widely used in staging of non-Hodgkin's lymphomas (NHL), but very few studies have focused on its role in the initial staging of patients with ocular adnexal lymphoma (OAL). The aim of this study was therefore to evaluate the role of (18)FDG PET in the diagnosis of ophthalmologic lymphoma. A retrospective review of all imaging records, including computed tomography (CT), magnetic resonance imaging (MRI), and FDG PET, was performed. Forty-one OAL patients were included in the study. A pathologic review according to the World Health Organization classification showed 32 low-grade lymphoma patients (78%), including 26 mucosa-associated lymphoid tissue lymphomas (63%). Ophthalmologic sites were intra-orbital + lacrimal gland in 24 patients (59%), conjunctival in 13 patients (32%), multiple in 4 cases, and bilateral in 6 patients. (18)FDG PET was positive in orbital and conjunctival sites in 68 and 35% of cases, respectively. (18)FDG PET positivity was correlated with pathologic sites detected by MRI in 22/30 patients (73%); (18)FDG PET positivity was correlated with pathologic sites detected by CT in 25/34 patients (73%). This study shows that (18)FDG PET has a lower sensitivity than MRI to detect ophthalmologic lymphoma, particularly in non-conjunctival sites.