Objective: Crystal-storing histiocytosis (CSH) is a very rare immunoglobulin (Ig) deposition disorder that can be associated with B-cell neoplasms as well as some reactive Ig-secreting lymphoproliferative disorders. This article reports the clinical, histopathologic, and molecular biologic findings of CSH in association with an extranodal marginal zone lymphoma (EMZL) of the lacrimal gland.
Design: Interventional case report with clinicopathologic correlation.
Intervention: Treatment consisted of conjunctival and orbital biopsies, as well as low-dose radiation of the left orbit.
Methods: Histopathologic findings of the conjunctival and orbital biopsies were compared. Further, extensive immunohistochemistry, polymerase chain reaction (PCR) for the detection of Ig heavy chain (IgH) gene rearrangement, Gene Scan analysis, and DNA sequencing were performed on all tissues.
Results: The tumor manifestations in the specimens demonstrated a similar morphologic and immunophenotypic characteristics consistent with the diagnosis of EMZL. Immunoglobulin H PCR and Gene Scan analysis showed B cells derived from the same clone. In association with the orbital EMZL were large accumulations histiocytes filled with refractile crystals, consistent with the diagnosis of CSH.
Conclusions: The current case describes an EMZL of the lacrimal gland appearing 5 years after excision and low-dose radiation of a conjunctival lymphoma. The orbital recurrence was associated with surrounding CSH, a rare Ig storage disorder more often reported in patients with multiple myeloma or lymphoplasmacytic lymphoma or immunocytoma. Ophthalmic pathologists should be aware of the diagnosis when reviewing orbital biopsies, because difficulties may arise when the crystal-storing macrophages occupy more tissue space than the Ig-secreting cells or when they resemble cell types such as rhabdomyoblasts.