Abstract
Purpose: We report a case of a 35-year old male who presented with unilateral conjunctival extranodal marginal zone (MALT) lymphoma and underwent systemic Rituximab immunotherapy as primary treatment. After an excellent initial response and four years of complete remission he presents with MALT lymphoma to the contralateral conjunctiva. Methods: MALT lymphoma is the most common lymphoid neoplasm of the conjunctiva, and has an indolent clinical course. Rare cases of spontaneous remission, bilateral involvement, systemic dissemination, and common local and contralateral relapses have been reported. Rituximab is a chimeric anti-CD20 antibody, currently used as first-line treatment of CD20 positive non-Hodgkin’s lymphoma. Several mechanisms can be responsible for rituximab resistance. Transformation of CD20 positive indolent to aggressive CD20 negative form is one of them. Results: In this case, the patient did not demonstrate any systemic or orbital involvement. Both histological reports of the incisional biopsies revealed CD20 positive immunohistochemistry. Conclusion: This is a highly unusual case of new primary conjunctival MALT lymphoma to the contralateral eye after systemic Rituximab treatment. This further supports the assumption that rituximab does not suppress MALT lymphoma formation in the long term in the other eye, suggesting that the predisposing immune factors are not annihilated by the course of rituximab. Long term review of these patients is therefore warranted.
Highlights
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is the most common lymphoid neoplasm of the conjunctiva
Orbital involvement and rarely a choroidal component [1] can occur, and this type of lymphoma is different to primary intraocular lymphoma of the vitreoretinal type [2,3]
MALT lymphomas are diagnosed by their strong staining for CD20 and negative staining for CD10, CD23, and bcl6 (Figure 2)
Summary
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is the most common lymphoid neoplasm of the conjunctiva. Orbital involvement and rarely a choroidal component [1] can occur, and this type of lymphoma is different to primary intraocular lymphoma of the vitreoretinal type [2,3] It is characterized by painless, salmon-pink patches in the fornix or bulbar conjunctiva, and has an indolent clinical course (Figure 1). MALT lymphomas are diagnosed by their strong staining for CD20 and negative staining for CD10, CD23, and bcl (Figure 2) Both orbits are involved in 15% of the cases - some synchronous and some metachronous [4]. It has been reported that all orbital lymphomas have a 5-year relapse-free survival of 65%, this increases to 85-90% for purely conjunctival lymphomas treated by conventional radiotherapy Such cases usually involve the contralateral orbit and distant extranodal organs. For example related to organ transplantation [6], thyroid eye disease [7], or chronic chlamydial infection [5] are known predisposing factors
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