Abstract
Pulmonary renal syndrome (PRS) is a combination of rapid progressive glomerulonephritis (RPGN) and diffuse alveolar hemorrhage (DAH) caused by a variety of immunological and non-immunological etiologies. The difficulty in identifying and reporting seronegative PRS cases could be attributed to the lack of specific immunological markers. Thus, we report a rare case of a 13-year-old boy who was initially diagnosed with idiopathic pauci-immune pulmonary capillaritis (IPIPC). A year later, his condition became complicated, and was referred for further workup. During his hospital stay, he underwent a renal biopsy that showed stage II membranous nephropathy (MN). He tested negative for immunological markers and a diagnosis of seronegative PRS was established. He responded well to the immunosuppression therapy with monthly follow-ups. As in our patient, PRS may manifest as acute renal failure symptoms and non-specific respiratory symptoms that require extensive workup. The severity of the disease is inferred from the renal function at the time of presentation. Management involves immunosuppression and treatment of the underlying condition, with dialysis dependency occurring in a significant percentage of patients and a high mortality rate, especially in critically ill and older patients. In conclusion, timely diagnosis and treatment are essential given the condition's rapid progression and high mortality rate.