Cytoplasmic Antineutrophil Cytoplasmic Antibodies (C-ANCA) Vasculitis: An Uncommon Complication After Stem Cell Transplantation.

Granulomatosis with polyangiitis (GPA) is a rare, autoimmune, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis of uncertain etiology. The incidence of autoimmune complications following stem cell transplant is around 2-5%, with autoimmune cytopenia reported most frequently. We present a case of a 65-year-old male patient who presented to the hospital with productive cough, dyspnea, and fever for five months after haploidentical stem cell transplantation. On presentation, he was febrile, tachypneic, and mildly hypoxic. Chest radiograph showed bilateral pulmonary infiltrates. An initial diagnosis of pneumonia was made, and the patient was started on antibiotics. The patient did not respond to initial management, and all his initial infectious workups came back negative. On further evaluation, cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) resulted positive in high titers. The patient was diagnosed with GPA, and IV methylprednisolone and rituximab were started. He responded well to treatment and was eventually discharged home. The classical form of GPA is characterized by the involvement of the upper respiratory tract, sinuses, lungs, and kidneys. Autoimmune disorders may develop secondary to hematopoietic stem cell transplant (HSCT). In our case, the patient was diagnosed with GPA, which is likely one of the autoimmune complications after HSCT.