Pulmonary-Renal Syndrome with Negative ANCAs and Anti-GBM Antibody

We report the case of a 76-year-old woman who was referred to our hospital for a gradually worsening cough and renal dysfunction. Although pneumonia was initially suspected, imaging findings of the lungs revealed diffuse alveolar hemorrhage at a later date. Renal failure developed and hemodiafiltration was performed on the 9th day. Rapidly progressive glomerulonephritis with crescent formation was diagnosed by renal biopsy. This case presentation has important clinical implications because uncategorizable pulmonary-renal syndrome (PRS) without the presence of ANCAs and anti-GBM antibody is extremely rare and has high rates of morbidity and mortality. No treatment has been established. 1. Introduction Pulmonary renal-syndrome (PRS), characterized by a combination of diffuse alveolar hemorrhage (DAH) and rapidly progressive glomerulonephritis (RPGN), is caused by varied etiologies, including Goodpasture’s syndrome, antineutrophil cytoplasmic antibody (ANCA)-associated small vessel vasculitis (ASVV), cryoglobulinemia, systemic lupus erythematosus, environmental factors, and certain drugs [1, 2]. ASSV, which can be caused by microscopic polyangiitis (MPA), Wegener’s granulomatosis, and Churg-Strauss syndrome, accounts for approximately 70% of the cases of PRS. Antiproteinase-3 (anti-PR3, c-ANCA) and antimyeloperoxidase (anti-MPO, p-ANCA) antibodies, which have been reported to play a major role in the pathogenesis of ASSV, are detectable in 70–90% of cases and facilitate diagnosis. Our present patient could not be classified into known subgroups because all commercially available serologic studies were negative. Therefore, a renal biopsy was performed for diagnostic clues at a later date. As a result, PRS was diagnosed on the basis of clinical manifestations and pathological findings. 2. Case Report A 76-year-old Japanese woman presented to our hospital complaining of a worsening cough of 10-day duration. Her past medical history included hypertension since age 70. Her activities of daily living had been independent before admission. On admission, her vital signs were as follows: body temperature, 35.3°C; heart rate, 86 beats/min; SpO2, 96% (on room air); respiratory rate, 14 breaths/min; and blood pressure, 161/78？mmHg. No skin lesions or peripheral neuropathy were noted. A laboratory examination revealed leukocytosis (white blood cell count [WBC]: 11,900/mm), normocytic normochromic anemia (Hb: 6.1？g/dL), elevation of C-reactive protein (CRP) level (6.1？mg/dL), and renal dysfunction (BUN: 42.6？mg/dL, Cr: 4.04？mg/dL). Urinalysis showed the following