Case Presentation: A 76-year-old man presented with two weeks of dyspnea on exertion and left lower extremity pain and swelling. He reported associated orthopnea, paroxysmal nocturnal dyspnea, and weight gain. He had COPD and OSA. He was diagnosed eight weeks prior to presentation with suspected hypereosinophilic syndrome after an admission with left pleural effusion. Thoracentesis revealed exudative effusion with pleural and peripheral eosinophilia. He was started on imatinib. Vital signs were normal on two liters of supplemental oxygen. He appeared anxious but in no distress. He had diminished lung sounds and bilateral 2+ lower extremity edema, worse on the left. He had bilateral erythematous raised lesions on both lower extremities on the medial aspect of his thigh and calf. White blood cell count was 18 K/uL with 6.7% eosinophils and an absolute eosinophil count of 1.52 K/uL. Creatinine was 2.10mg/dL. Urinalysis showed trace protein, 2+ blood, 5-9 RBCs, 5-9 WBCs, and few granular casts. NT-pro-BNP was 17000pg/mL. Chest x-ray demonstrated mild cardiomegaly and blunting of both costophrenic angles with bilateral interstitial infiltrates likely representing fluid overload. Lower extremity venous duplex was negative for DVTs, however, the aforementioned lesions were revealed to be superficial thrombi. Transthoracic echocardiogram demonstrated impaired left ventricular relaxation with preserved ejection fraction. Further investigation of eosinophilia and renal failure including RF, ANA, C-ANCA, P-ANCA, MPO, PR3, Anti-DS, flow cytometry, and Strongyloides IgG and stool O&P were negative. The patient’s renal failure worsened. Renal biopsy showed necrotizing crescentic glomerulonephritis with 2+ linear staining along capillary walls consistent with anti-glomerular basement membrane (GBM) disease. GBM IgG was elevated at 90 (0-19 considered normal). He was placed on high-dose dexamethasone, cyclophosphamide, and underwent plasmapheresis. He improved and renal failure stabilized and was discharged to a rehab facility.
Discussion: Identifying an initial differential diagnosis for eosinophilia is important for a hospitalist. The CHINA mnemonic is a helpful tool to remember the differential diagnoses. The mnemonic is as follows: C for connective tissue diseases, H for helminthic infections, I for idiopathic hypereosinophilic syndrome, N for neoplasia, and A for allergies. Eosinophilic granulomatosis with polyangiitis is a vasculitis strongly associated with eosinophilia. Other connective tissue diseases associated with eosinophilia include systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, Sjögren’s syndrome, and dermatomyositis. Anti-GBM disease classically presents with clinical features that resonate with rapidly progressive glomerulonephritis. Pulmonary involvement when present generally consists of alveolar hemorrhage. This is a case of anti-GBM disease first presenting with significant eosinophilia which then progressed to the more classic renal involvement. There are case reports describing an association of anti-GBM disease and eosinophilic vasculitis.
Conclusions: This case is an example of a rare presentation of anti-GBM disease that initially masqueraded as idiopathic hypereosinophilic syndrome. When evaluating patients with peripheral eosinophilia, remembering the CHINA mnemonic is a useful way to guide history and examination.