Isolated optic nerve involvement in chronic lymphocytic leukaemia

Abstract

Abstract Purpose We present a case of isolated optic nerve involvement by B‐cell small lymphocytic lymphoma/chronic lymphocytic lymphoma (SLL/CLL). Methods A 57 year old woman with CLL stage 1 developed right‐sided visual loss progressing to blindness. There was optic disc swelling and secondary central retinal vein occlusion (CRVO). Imaging revealed a thickened right optic nerve. A clinical diagnosis of optic nerve sheath meningioma was made. Biopsies were taken from optic nerve sheath and abnormal‐looking optic nerve tissue. Results Histopathology revealed infiltration of optic nerve by small B‐cell lymphoma, with CD5, CD20 and CD23 positive, cyclin D1 negative, neoplastic B‐cells, with kappa light chain restriction. Molecular genetic analysis with heavy chain primers confirmed a dominant band of PCR products, consistent with monoclonal B‐cell expansion. This lymphoma phenotype was consistent with that of the previously diagnosed stage 1 CLL. Optic nerve sheath dura was uninvolved, with reactive meningeal hyperplasia only. Conclusion Although primary intraocular lymphoma and optic nerve lymphoma are present in up to 20% of cases of primary central nervous system lymphoma, isolated optic nerve lymphoma is rare. We believe this case is only the sixth reported where optic nerve biopsy was diagnostic. Other authors have noted the lack of dural involvement by lymphoma in this condition. We wish to add that in addition to potential diagnostic failure if optic nerve sheath alone is biopsied, the presence of reactive meningeal hyperplasia might lead to an erroneous diagnosis of optic nerve sheath meningioma on an inadequate biopsy specimen. Also, it is possible for accurate diagnosis to be achieved without sacrificing the optic nerve, although visual loss may not be avoided.