A 54-year-old man with a 4-month history of recurrent sinusitis, 100-lb unintentional weight loss, gait instability, and generalized weakness presented with headache and painless, bilateral visual loss. Bilateral temporal artery biopsies were performed and showed no arteritis. Magnetic resonance imaging (MRI) of the brain revealed mild meningeal enhancement and a chronic subdural hematoma causing mild midline shift. Following surgical drainage, visual acuity remained unchanged, and his headaches worsened. Pertinent clinical findings were no light perception in both eyes, amaurotic pupils, and bilateral mild, temporal optic disc pallor. Ocular coherence tomography (OCT) of both optic nerves demonstrated normal nerve fiber layer thickness. Laboratory tests failed to suggest an etiology of his vision loss. Lumbar puncture showed lymphocytic pleocytosis but cytology and flow cytometry were negative for lymphoma. Repeat brain MRI was performed and demonstrated diffuse pachymeningeal enhancement (Fig. a) with possible involvement of the optic nerve sheath (Fig. b); a dural biopsy was performed.\nHistopathology demonstrated a dense infiltrate of lymphocytes and plasma cells, with no definite vasculitis or granulomatous inflammation (Fig. c, d). The possibility of marginal zone lymphoma was considered but was ruled out by immunohistochemistry, with T cells (CD3-positive) outnumbering B cells (CD20-positive), and with in situ hybridization revealing a kappa:lambda ratio of <4:1 among the plasma cells (not shown). In situ hybridization for Epstein-Barr virus was negative (not shown). Additionally, molecular genetic studies did not show any evidence of a clonal IgH gene rearrangement by polymerase chain reaction (PCR). However, IgG4 immunostain was markedly positive, with 40 IgG4-positive cells per high-power field (HPF), comprising over 40 % of the total plasma cell population (Fig. e, f). (The total plasma cell population was assessed with CD138 immunostain, and IgG immunostain was also obtained, showing that all IgG-positive cells were also IgG4-positive, i.e., IgG4:IgG ratio of 1, not shown). Subsequent bone marrow biopsy also showed no evidence of lymphoma (small CD19-positive B-cell population with normal kappa:lambda light chain ratio), and fine-needle aspiration biopsy of a left supraclavicular lymph node showed similar findings negative for lymphoma.\nOn his systemic work-up, p-ANCA was borderline positive, and serum IgG showed elevated IgG4 subclasses (148.0; normal range 2.4–121.0). Accordingly, the diagnosis of IgG4-related meningeal disease was made. The patient was started on aggressive immunosuppression with high-dose corticosteroids to be followed by either cyclophosphamide or rituximab. However, due to insurance issues, he was able to receive only methotrexate. There was near-total resolution of meningeal enhancement on repeat MRI, but his visual acuity improved to only bare light perception in both eyes. He remains stable on methotrexate almost 1 year from his diagnosis.
A 76-year old man with a history of bilateral lacrimal gland masses and an otherwise unremarkable ocular examination underwent left orbital biopsy at another institution. Clinical suspicion was high for possible lymphoma due to the additional presence of cervical and axillary lymphadenopathy. The histologic diagnosis at that time was reactive lymphoid hyperplasia with fibrosis. Immunohistochemistry, kappa/lambda in situ hybridization, and flow cytometry were negative for lymphoma. The patient was lost to follow-up without any further work-up. He presented a year later due to recurrence of orbital inflammation, at which point the surgeon requested histologic work-up for IgG4-related disease. The slides from the prior orbital biopsy were requested and reviewed, showing lymphoid follicles with intervening bands of fibrosis and mixed chronic inflammatory cells. The tissue block was also received, and additional sections were cut for CD138 and IgG4 immunostaining. There were at least 150–180 IgG4-positive plasma cells per high-power field, comprising over 40 % of the total plasma cell population (as assessed by CD138). (Serum IgG4 was not obtained.) This was considered consistent with IgG4-associated orbital inflammatory pseudotumor with sclerosing features. The patient was initially treated with prednisone and then transitioned to intravenous rituximab as first-line therapy and had an excellent response with no recurrence at 2 years following therapy.