Orbital immunocytoma simulating Hodgkin's disease by mimicking Hodgkin- and Reed-Sternberg-like cells

Purpose. The present case report describes primary orbital immunocytoma (IgM-kappa) mimicking Hodgkin's disease of the diffuse, lymphocyte predominance type by expressing Hodgkin simulating cells as well as Reed-Sternberg simulating cells (both: H-RS cells). Patients and methods. The patient (87a; male) was admitted to hospital with increasing left upper eyelid protrusion. Computed tomography revealed an unspecific accumulation of soft tissue within the orbit. A biopsy was taken. Light microscopical sections were stained with PAS, Giemsa and haematoxylin-eosin. Immunohistochemistry was performed following standard procedures. Results. By means of light microscopy, Hodgkin's disease of the diffuse, lymphocyte predominance type was indicated. This initial diagnosis was mainly based on morphological criteria, e.g. the presence of H-RS-like cells. Since staging work-up produced no evidence of systemic disease, immunohistochemistry was performed. It revealed that the misleading cells were H-RS simulating cells. Finally, the diagnosis made was that of immunocytoma (IgM-kappa); stage I EA. Conclusion. The diagnosis of Hodkin's disease of the diffuse, lymphocyte predominance type is normally based on morphological criteria. However, in very rare cases immunocytomas simulate this variant of Hodgkin's disease by expressing misleading H-RS simulating cells. Thus, immunohistochemical investigations should generally be included in the criteria for the diagnosis of Hodgkin's disease of the diffuse, lymphocyte predominance type. As far as we are aware, primary immunocytoma mimicking this variant of Hodgkin's disease within the orbit has never been reported.