Drug Induced Autoimmunity: Propylthiouracil Induced ANCA Vasculitis

A 57-year-old woman with a history of hypertension and hyperthyroidism presented with recurrent vomiting and loose stools since the past 7–8 months on November 8, 2017. She noticed blackish discoloration over her nasal tip and toes, along with a non-healing skin lesion on her left leg Figures 1 and 2. She had been taking an unsupervised regimen of propylthiouracil (PTU) 50 mg daily for her hyperthyroidism. On examination, she appeared delirious and pale, with large hyperpigmented patches and erythema on her skin. Laboratory tests revealed pancytopenia (hemoglobin-6.9 mg/dL, total count-3720/cubic mm, neutrophil-87%, lymphocyte-10%, monocyte-3%, platelet count-113 000/cubic mm), elevated ESR, a low serum TSH-0.03 m IU/L, and hypoalbuminemia (s. albumin-2.3 g/dL), with positive p-ANCA (22.3 RU/mL). A skin biopsy confirmed leukocytoclastic vasculitis. What is the condition affecting this patient? Answer: The patient was diagnosed with PTU-induced Anti-Neutrophil Cytoplasmic Antibody (ANCA)-associated vasculitis and pancytopenia. PTU, a medication commonly used for hyperthyroidism, can trigger autoimmune responses, including ANCA-associated vasculitis, which is confirmed by the positive p-ANCA and clinical findings [1, 2]. ANCA-associated vasculitis represents a group of potentially life-threatening autoimmune diseases characterized by multi-system involvement [3]. Immediate cessation of PTU and administration of intravenous methylprednisolone significantly improved her symptoms [3]. Patient's delirium, pancytopenia resolved (hemoglobin-11.6 mg/dL, total count-5300/cubic mm, neutrophil-64%, lymphocyte-32%, monocyte-3%, eosinophil-1%, platelet count-211 000/cubic mm) and hypoalbuminemia improved (s. albumin-3.8 g/dL) by December 6, 2017. Her skin lesions began to heal. Four months later, she underwent successful nasal tip reconstruction and a split-thickness skin graft for the necrotic tissue. PTU-induced ANCA vasculitis is serious but manageable with prompt recognition and intervention [4, 5]. Physicians should suspect vasculitis in PTU-treated patients presenting with relevant symptoms, especially with systemic involvement. The positive response to the discontinuation of PTU and steroid therapy in this case underscores the importance of early and appropriate management. Authors have contributed equally to this article. The authors have nothing to report. We state that we obtained the patient's written informed consent to publish the material. The authors declare no conflicts of interest. The authors have nothing to report.