Orbital Involvement in Bing-Neel Syndrome

Abstract

We read the article “Orbital Involvement in Bing-Neel Syndrome” by Stacy et al (1) with great interest and commend the authors for their excellent discussion of the manifestations of Waldenström macroglobulinemia (WM) in the orbit and brain. We had the opportunity recently to see a similar patient with WM and diffuse orbital involvement whose clinical course demonstrates that the visual outcome in these patients may be poor despite aggressive therapy. A 57-year-old man was referred to a retina specialist with a 3-week history of progressive, painless, bilateral visual loss. His medical history was significant for WM diagnosed 9 years previously, for which he was treated with 5 cycles of cyclophosphamide, rituximab, and prednisone, most recently 1 year prior to presentation. On examination, visual acuity was 20/160, right eye, and 20/32, left eye. Anterior segments were quiet, eye movements were full, and there was no proptosis. Dilated fundus examination revealed bilateral optic disc edema greater in the right eye than in the left eye, with a normal appearance of the retinal vessels, macula, and periphery. Fluorescein angiography showed leakage and staining of the optic discs. Infiltrative optic neuropathy was suspected, and he was started on oral prednisone 80 mg daily and referred immediately to his oncologist. MRI of the orbits revealed enhancement of the orbital fat and optic nerves (Fig. 1). Serum IgM was elevated at 1,350 mg/dL (range, 40-230 mg/dL). Chemotherapy with cyclophosphamide, vincristine, prednisone, and rituximab was initiated. However, vision declined to hand motions, right eye and 20/50, left eye, within 3 weeks of initial presentation. A right orbital biopsy was performed, and histopathologic examination revealed fibroadipose tissue with patchy aggregates of small lymphocytes, scattered plasma cells, and histiocytes. Immunoperoxidase staining of the lymphocytes was positive for CD20, CD79a, and CD138 and negative for CD23, CD5, CD10, and BCL-1. These matched markers from the patient's previous bone marrow biopsies, confirming orbital infiltration of WM.FIG. 1: Contrast-enhanced axial (A) and coronal (B) fat-suppressed T1 orbital MRI scans show patchy enhancement of orbital fat, enlargement of the extraocular muscles, and thickening and enhancement of the orbital segments of the optic nerves.The patient was hospitalized for intravenous infusion of high-dose methotrexate and intrathecal cytarabine. A lumbar puncture yielded lymphocytes in insufficient number for flow cytometry. The patient received external beam orbital radiation therapy in 18 fractions for a total dose of 30.6 Gy. Despite treatment, the patient's vision declined to no light perception in each eye. Stacy et al (1) noted that other than slight resistance to retropulsion, their patient's external examination gave no hint of the diffuse infiltration of the orbital fat and optic nerves by malignant cells found on neuroimaging and confirmed with orbital biopsy. They suggested the absence of proptosis could be explained by an almost equal replacement of fat by tumor. Similarly, except for bilateral optic disc edema and progressive visual loss, our patient's clinical examination offered no clues to the extent of the orbital and optic nerve involvement found on MRI. Our case differed somewhat in that severe visual loss occurred early and progressed rapidly to complete bilateral blindness despite aggressive therapy. In addition, our patient's MRI demonstrated involvement of the extraocular muscles. That such diffuse infiltration of orbital tissue can occur without proptosis or orbital congestion, and with preservation of eye movements, is striking. Rishi R. Doshi, MD Rona Z. Silkiss, MD, FACS Richard K. Imes, MD California Pacific Medical Center, San Francisco, California [email protected]