Ocular adnexal IgG4-related disease: comparative analysis with mucosa-associated lymphoid tissue lymphoma and other chronic inflammatory conditions.

Aims: Making a differential diagnosis of IgG4-related disease from mucosa-associated lymphoid tissue (MALT) lymphoma or any other chronic inflammation is often challenging. Moreover, the association with secondary lymphoma of ocular adnexal IgG4-related disease needs to be elucidated.
Methods and Results: We investigated 14 cases of IgG4-related disease, nine MALT lymphomas and 12 other chronic inflammations involving the lacrimal gland and orbit. Bilateral involvement was frequent in IgG4-related diseases. The number of IgG4-positive cells and the ratio of IgG4/IgG-positive cells were higher in patients with IgG4-related disease than in those with MALT lymphoma (P = 0.016; P < 0.001) and other types of inflammation (P < 0.001; P < 0.001). Monoclonal B cell proliferation was suspected in two cases (14.3%) of IgG4-related disease. One of these patients also displayed monomorphous features suggesting secondary MALT lymphoma. In the other case, κ-chain restriction in IgG4-positive cells was observed, raising the possibility of IgG4-producing MALT lymphoma. Trisomy 3, trisomy 18 or MALT1 translocation was observed in none of the IgG4-related cases. Regulatory T-cell infiltration was higher in cases of IgG4-related disease than in MALT lymphomas (P < 0.001) and other types of inflammation (P = 0.006).
Conclusions: Some genetically and morphologically complicated cases of ocular adnexal IgG4-related disease emphasize the need for in-depth studies to differentiate this disease from MALT lymphoma, and to exclude secondary lymphoma.
(© 2011 Blackwell Publishing Limited.)