Henoch-Schönlein Purpura Presenting as Mononeuritis Multiplex

Dear Editor, Mononeuritis multiplex (MM) is a syndrome of the peripheral nervous system (PNS) involving progressive multifocal peripheral nerve lesions. Its distribution is typically asymmetric, and the course of the disease varies with the underlying etiology. MM is associated with several medical conditions, including vasculitis, immune-mediated diseases, diabetes, infections, neoplasms, infiltrative diseases, and drugs. Henoch-Schönlein purpura (HSP) is an IgA-mediated small-vessel vasculitis, and also a rare cause of MM.1 The prevalence of HSP is lower in adults than in children, and no cases of MM with HSP in Korea have been reported previously. Here we report a case of MM with HSP in a Korean patient. A 57-year-old female patient visited the emergency room due to weakness of her right ankle and right hand. She had been diagnosed with rheumatoid arthritis (RA) 10 years previously due to multiple arthralgia. Her RA was well controlled with medication, and she had no arthralgia at the present visit. One day before her presentation she had experienced shock-like pain that developed along her right upper arm and in her right ankle. A neurologic examination revealed weakness of wrist flexion, thumb abduction, and ankle dorsiflexion, and hypesthesia of the right finger tips and foot dorsum. Purpuric skin lesions had developed on both feet 1 year before the current presentation, and the patient reported diffuse nonspecific abdominal pain (Supplementary Fig. 1 in the online-only Data Supplement). She had undergone a skin biopsy 1 month previously, which revealed leukocytoclastic vasculitis and IgA deposition within the purpuric lesion. The patient was diagnosed with HSP based on IgA vasculitis, purpuric skin lesions, and diffuse abdominal pain. A nerve conduction study revealed multifocal axonal neuropathy (Table 1), leading to a diagnosis of MM. Laboratory tests revealed mild leukocytosis, elevated C-reactive protein and increased erythrocyte sedimentation rate (60.3 mg/L and 45 mm/hr, respectively). The findings of serologic tests were negative for antineutrophil cytoplasmic antibody, anti-SS-A antibody, anti-SS-B antibody, antinuclear ribonucleoprotein antibody, anti-Smith antibody, antihistone antibody, anti-double-stranded DNA antibody, cold agglutinin, and cryoglobulin. She was positive for antinuclear antibody at a titer of 1:640 and with a nucleolar pattern, and her serum rheumatoid factor was elevated (to >120 IU/L). The patient underwent methylprednisolone pulse therapy (1 g per day for 5 days) without significant complications, and she was maintained on low-dose oral steroid. Her ankle and wrist weakness had improved at the 1-year follow-up, but the sensory loss persisted. Among various etiologies, the most common cause of MM is vasculitic process, while HSP is rare.2 HSP is an immune complex vasculitis that predominantly affects small vessels, and is characterized by nonthrombocytopenic palpable purpura, abdominal involvement, arthralgia, and renal involvement. Its pathophysiology remains unclear, but IgA is thought to play an essential role.3 HSP mainly occurs in children and is uncommon in adults. FurtherMincheol Park Younggun Lee Young-Chul Choi