IgG4-Related Hepatic Disease Unmasking Hepatic Actinomycosis

PURPOSE: Hepatic actinomycosis is a rare granulomatous disease caused by an opportunistic Gram-positive bacillus of the genus Actinomyces. We report an unusual association between hepatic actinomycosis and IgG-4 related disease. CASE DESCRIPTION: A 70-year-old man was admitted to the University Hospital of Reunion Island for asthenia and abdominal pain. Laboratory tests showed hepatic cholestasis and inflammatory reaction without cytolysis. The computer tomography scanner (CT scan) revealed a large hepatic mass in segment IV. IgG4 related disease (IgG4-RD) was diagnosed following liver biopsy. Despite the use of corticosteroids, the lesions progressed. A new biopsy was performed and a PCR test returned positive for Actinomyces spp. We observed patient improvement after 4 months of treatment with amoxicillin and discontinuation of corticosteroids. CONCLUSIONS: Clinical presentation, imaging characteristics, and diagnostic challenges are strikingly similar between hepatic actinomycosis and IgG4-related disease. However, distinguishing between these two disorders is essential - as the treatment of one may worsen the course of the other. Knowing and understanding the interactions between these two disorders can only be achieved through an integrated and collaborative approach involving various disciplines.