Hepatic Monoclonal Light‐ and Heavy‐Chain Deposition Disease Presenting as Noncirrhotic Portal Hypertension With Ascites

Monoclonal immunoglobulin deposition disease (MIDD) is a plasma cell disorder where immunoglobulin light‐ and/or heavy‐chains accumulate in various organs. Hepatic involvement can be challenging to diagnose, as manifestations are protean and Congo red staining is negative. We report a patient with IgG kappa plasma‐cell dyscrasia who developed refractory ascites despite normal liver tests and function. Transjugular liver biopsy showed mild portal and periportal vascular changes with minimal perisinusoidal fibrosis, and Congo red staining was negative. Immunofluorescence demonstrated diffuse linear IgG1 and kappa deposition along the sinusoids and space of Disse, establishing hepatic light‐ and heavy‐chain deposition disease (LHCDD). This case highlights hepatic LHCDD as a rare cause of noncirrhotic portal hypertension and emphasizes the diagnostic value of hepatic immunofluorescence when routine histology and Congo red staining are nondiagnostic.