Pulmonary Infiltrates With Eosinophilia (PIE) Complicated by Autoimmune Hemolytic Anemia (AIHA)

Abstract

INTRODUCTION: PIE syndromes are caused by a large number of infectious and immune-mediated conditions. We present a case of unexplained PIE syndrome complicated by AIHA. CASE PRESENTATION: An 85 year old non-smoking, non-asthmatic male was evaluated for chronic cough and peripheral eosinophilia. Medication, travel or exposure history was nonsignificant. Physical exam was unremarkable. Hemogram revealed an absolute eosinophilia of >5000 cells/uL for >6 months duration. Autoimmune serologies were unrevealing. Imaging studies showed nodular infiltrates and lymphadenopathy (Figure 1). Bronchoscopy was notable for 19% eosinophilia in the lavage and tissue eosinophilia in transbronchial lung and lymph node biopsy samples. All cultures were negative. Based on mild symptoms, he opted for close observation. 9 months later, he was admitted with fatigue and dyspnea. Labs were pertinent for new normocytic anemia (Hgb 7.2 g/dL), persistent eosinophilia, reticulocytosis, elevated lactic dehydrogenase and indirect hyperbilirubinemia. Peripheral smear showed spherocytes. The direct Coombs test was positive. DISCUSSION: PIE syndromes are a heterogeneous group of disorders. It can be subdivided into primary lung process, like eosinophilic pneumonia, and secondary causes, including infectious, autoimmune, hematologic, or allergic disorders. When associated with unexplained peripheral or tissue eosinophilia and evidence of organ injury, PIE may occur in the context of hypereosinophilic syndrome (HES). Anemia with hypereosinophilia is usually due to marrow infiltration and rarely associated with AIHA. Specifically, AIHA has been reported with myeloproliferative eosinophilic disease and eosinophilic granulomatosis with polyangitis. Our patient had no evidence of these disorders. There is only one report of AIHA in association with HES. A shared pathogenesis between hypereosinophilia and AIHA cannot be proven in these cases. However, the concurrence of two rare entities suggests a common cause. One plausible explanation is the role of IL-5, which stimulates antibody production via the T helper-2 pathway and is a key mediator in eosinophil activation. CONCLUSIONS: Our patient was treated for AIHA with red blood cell transfusion and systemic corticosteroids. The etiology of hypereosinophilic syndrome remains unclear. Within a week of initiating systemic steroids his anemia and peripheral eosinophilia resolved. Likewise, his nodular lung disease has improved. He remains on a gradually tapering dose of corticosteroids.