A 22-year-old female presented to the hospital with worsening pain and weakness in her left lower extremity. The patient reported non-healing ulcerations along her left leg and foot for the past month that she initially attributed to a bug bite while in the woods. She originally presented to an outside hospital and was treated with antibiotics for a presumed cellulitis, but the ulcers did not improve and her pain worsened. Her physical exam was remarkable for a left foot drop, numbness in her left lower extremity distal to her knee extending to her toes, and ulcerations measuring 2-7 cm in diameter that were necrotic with surrounding erythema. Her labs were unremarkable and her inflammatory markers were normal. She had an extensive serologic work up including HIV, hepatitis panel, ANCA, ANA, complements, and coagulopathy panel that were normal. Given the concern for potential toxin from an insect bite, infectious disease evaluated the patient, but did not believe her symptoms were consistent with a toxin. Dermatology performed biopsies of the ulcerations revealing extensive coagulative necrosis as well as fibrinoid necrosis surrounding several medium-sized vessels. Neurology conducted an electromyography that showed severe axonal neuropathies affecting the tibial and peroneal-innervated muscles distal to the knee in the left leg, consistent with nerve involvement vasculitis. After multi-disciplinary review of the case, the patient was diagnosed with polyarteritis nodosa and rheumatology recommended pulse dose steroids followed by a prednisone taper. Throughout her stay she continued to have refractory pain, but her pain was eventually controlled using a multimodal pain management approach. The erythema surrounding the necrotic ulcers improved with steroids, but her neuropathy and foot drop persisted. She was discharged home with follow up with physical therapy and rheumatology for initiation of rituximab infusions.
Discussion:
Vasculitides are rare diseases with variable clinical presentations. Peripheral neuropathy is commonly associated with polyarteritis nodosa (PAN) and can be the initial manifestation in up to 85% of patients. The incidence of PAN is 2 to 9 per million a year in the US and Europe. PAN is an ANCA negative vasculitis affecting the small and medium sized vessels. The diagnosis requires a high degree of clinical suspicion and quick evaluation with histopathology in order to provide proper treatment.
Conclusions:
Diagnosing polyarteritis nodosa can be challenging due to the multitude of clinical manifestations. Weakness, neuropathy, weight loss, and cutaneous lesions are some of the many features of PAN. The clinician should perform a detailed history and physical examination, laboratory evaluation, and histologic evidence showing necrotizing vasculitis. The variable presentations frequently require multi-disciplinary review. Early recognition and treatment leads to an improvement in outcomes and a reduction in morbidity and mortality.