Optic neuritis in a psoriatic arthritis patient treated by infliximab

Dear Editor, We report a case of psoriatic arthritis (PA) who developed optic neuritis (ON) during infliximab therapy. To the best of our knowledge, this is the first report of ON associated with infliximab in a Japanese psoriatic patient. The patient was a 55year-old man who had arthritis of finger joints, wrists and elbows, and well-demarcated hyperkeratotic scaly erythematous plaques on the umbilicus, groins, trunk and scalp (Fig. 1). Histopathology of the thigh lesion revealed hyperkeratosis, parakeratosis and neutrophilic microabscess in the horny layer. Absence of granular layer and elongation of rete ridges were compatible with psoriasis (Fig. 2). He did not have any prior history of demyelinating diseases. Anteroposterior radiographic finding of hands revealed narrowing of joint spaces with bone proliferation on all distal interphalangeal joints. His 28-joint Disease Activity Score based on C-reactive protein was 3.21. While skin lesions were well controlled with topical corticosteroid and active vitamin D3 ointment, joint pain was aggravated. Tuberculin skin test was positive and computed tomography detected two small old granulomatous nodules on his left lung. He was given isoniazid 300 mg once daily according to the Japanese standard guideline. After he received infliximab, his skin lesions and arthritis disappeared. However, he noticed numbness of the hands and feet 4 weeks after the fifth infusion of infliximab. Isoniazid-induced peripheral neuropathy was suspected and rifampicin 450 mg once daily was initiated instead of isoniazid. However, 4 weeks after the sixth infusion of infliximab, he developed blurred vision and superior visual field depression in his right eye. Best corrected visual acuity (BCVA) of the right eye was 20/100. The results of contrast-enhanced brain magnetic resonance imaging (MRI) and lumbar puncture were normal. Neither anti-aquaporine-4 antibody nor evidence for multiple sclerosis (MS) was detected. He was diagnosed as right ON by ophthalmologists in our hospital. Following i.v. methylprednisolone (1000 mg/day 3 days), oral predonisone was prescribed and tapered off. His vision improved gradually in the subsequent 8 weeks. His BCVA was 20/20 in the right eye and his visual field recovered completely. The numbness of hands and feet also gradually disappeared following the corticosteroid therapy. Rheumatoid factor and antinuclear antibodies were negative throughout the course, and there was no change of immunoglobulin levels during the development and course of ON. He did not receive further infliximab therapy. Tumor necrosis factor (TNF)-a inhibitors are used for rheumatoid arthritis, inflammatory bowel diseases and PA. There are several adverse events, however, after the TNF-a antagonists therapy, such as infections, congestive heart failure, and demyelinating diseases including MS and ON. ON is an inflammatory optic nerve demyelinating disease that is primary or MS-associated. Specific brain MRI abnormalities suggest the association with MS. Twenty-three cases of ON associated with TNF-a antagonists have been reported up until December 2011. Fifteen Figure 1. Well-demarcated hyperkeratotic scaly erythematous plaques on groins and pubic area. Figure 2. Histopathology of the lesion revealed hyperkeratosis, parakeratosis and microabscess of neutrophils in horny layer (hematoxylin–eosin, original magnification 9100). The epidermis showed absence of granular layer and mild acanthosis.