A case of spontaneous regression of primary hepatic diffuse large B-cell lymphoma.

We report a rare case of spontaneous regression of primary hepatic diffuse large B-cell lymphoma (DLBCL) in an 89-year-old man. A 12 cm solitary hepatic mass was found in the anterior and medial segments. Contrast-enhanced CT showed a hypovascular solid tumor. Serologic markers including hepatitis B virus, hepatitis C virus, human immunodeficiency virus, alpha-fetoprotein, protein induced by vitamin K absence or antagonist-II, carbohydrate antigen 19-9, and carcinoembryonic antigen were negative, but soluble interleukin-2 receptor was elevated. Ultrasound-guided liver biopsy confirmed DLBCL, and the diagnosis of primary hepatic lymphoma was established based on Caccamo's criteria. The patient declined chemotherapy or radiotherapy due to age and preference, and was observed without treatment. Initially, the tumor grew slightly, but later imaging showed spontaneous regression without intervention. No recurrence or progression was observed during 15 months of follow-up. The regression may have been triggered by an immune response, possibly induced by biopsy-related stimulation. Primary hepatic lymphoma is extremely rare, accounting for 0.07% of malignant liver tumors, and spontaneous regression of untreated DLBCL is exceedingly uncommon. This case highlights the potential role of immune-mediated mechanisms in spontaneous tumor regression and supports careful observation as a possible management strategy in select elderly patients with primary hepatic lymphoma.