Ocular adnexal marginal zone B cell lymphoma infiltrated by IgG4-positive plasma cells

Aims: To report the clinicopathological characteristics of patients with ocular adnexal marginal zone B cell lymphoma (MZBL) with IgG4-positive plasma cells. Methods: 114 biopsy samples of ocular adnexal MZBLs were analysed. MZBLs with IgG4-positive plasma cells were included when the IgG4:IgG ratio was >40% (IgG4-related group). The serum levels of each subclass of immunoglobulins and soluble interleukin-2 receptor in the IgG4-related group were compared with those in 61 consecutive patients having MZBL without IgG4-positive plasma cells (IgG4-unrelated group). They were also compared with those in 10 patients having ocular adnexal IgG4-related lymphoplasmacytic disorder (IgG4-related inflammatory group). Results: Ten (9%) of the patients were diagnosed with MZBL with IgG4-positive plasma cells. The IgG4-related group had a significantly greater degree of sclerosis and reactive follicles in the MZBLs (p=0.0004 and p=0.01, respectively). The serum levels of IgG, IgG1, IgG4, IgE and soluble interleukin 2 receptor in the IgG4-related group were significantly higher than those in the IgG4-unrelated group (p=0.003, p=0.009, p<0.0001, p<0.0001 and p=0.0007, respectively). The serum levels did not differ significantly from those of the IgG4-related inflammatory group. The IgG4-related group also had reactive IgG4-positive lymphoplasmacytic infiltrations in the recurrent lesion and in the stomach. Conclusions: IgG4-positive plasma cells had infiltrated into ocular adnexal MZBLs in 9% of cases. It is suggested that ocular adnexal MZBLs with IgG4-positive plasma cells have unique histological and serological characteristics that overlap those of ocular adnexal IgG4-related lymphoplasmacytic infiltrative disorder and systemic conditions.