Skin biopsies in the evaluation of atypical optic neuropathies

Patients with atypical clinical presentations of common optic neuropathies such as optic neuritis (ON), anterior ischemic optic neuropathy (AION), or optic neuropathy of unknown etiology (UON) are difficult to distinguish from inflammatory autoimmune optic neuropathy (AON) which is typically associated with a poor visual prognosis, unless treated with high doses of corticosteroids and/or immunosuppressive agents. The authors retrospectively evaluated 34 patients [AON (n = 12); AION (n = 5); ON (n = 9); UON (n = 8)] with visual loss which deteriorated over weeks to months or followed an atypical course, for the presence of immunological markers suggestive of AON. These markers included serological testing for antiphospholipid (APA) and antinuclear (ANA) antibodies, and evaluation of histopathologic and immunofluorescent staining of skin biopsies. All patients underwent a skin biopsy. Four of the 12 patients with AON had urticarial cutaneous lesions which revealed leukocytoclastic and/or lymphohistiocytic vasculitis. Seven of the remaining eight AON patients had skin biopsies of non-lesional skin which revealed immunoreactant deposition. Seven of the 21 skin biopsies obtained from the non-AON patients had findings of vacuolization or mild perivascular infiltration of lymphocytes (n = 5) and immunofluorescent deposits (n = 2). Abnormal skin biopsies (92%;p = 0.0009) and circulating APA (82%; p = 0.013) were common in AON patients while ANA was not statistically increased in AON patients (p = 0.06) when compared to the remaining patients as a whole. AON patients typically demonstrate evidence of systemic autoimmune involvement, as manifested by cutaneous abnormalities such as urticarial vasculitis and/or immunoreactant deposition and circulating APA. These may serve as markers for identifying AON patients who may be treated with immunomodulatory agents.