Multisystem Hepatic Sarcoidosis With Hypereosinophilia and Elevated IgG4 Mimicking IgG4-Related Disease and Lymphoma: A Diagnostic Challenge.

Sarcoidosis is a multisystem granulomatous disease that can involve multiple organ systems, present with varied clinical features, and overlap diagnostically with malignancy and immune-mediated disorders. We report the case of a 39-year-old woman who presented with mild dyspnea, generalized weakness, and unintentional weight loss, accompanied by marked hypereosinophilia. Laboratory evaluation revealed a cholestatic pattern of liver injury, elevated total serum IgG, markedly elevated serum IgG4, elevated serum IgE, polyclonal hypergammaglobulinemia, and elevated serum angiotensin-converting enzyme levels. Cross-sectional imaging demonstrated marked hepatosplenomegaly with multiple nodular lesions, extensive abdominal and mediastinal lymphadenopathy, and bilateral subpleural pulmonary nodules. Given these findings, an infiltrative or malignant process was initially suspected. Excisional lymph node biopsy revealed non-necrotizing granulomatous inflammation consistent with sarcoidosis. Bone marrow aspiration and biopsy demonstrated preserved hematopoiesis without abnormal cellular infiltration, while acid-fast bacilli staining and mycobacterial cultures were negative, effectively excluding hematologic malignancy, tuberculosis, and primary hypereosinophilic syndromes. This case expands the limited literature on hepatic sarcoidosis presenting with marked hypereosinophilia and elevated serum IgG4, emphasizing the importance of histopathological confirmation and systematic exclusion of alternative diagnoses.