Spontaneous Regression of Adult Multi-system Langerhans Cell Histiocytosis Presenting as Liver Tumor Rupture.

Adult multisystem Langerhans cell histiocytosis (MS-LCH) is rare and has a poor prognosis. A 67-year-old man with MS-LCH presented with a hepatic tumor rupture and multiple masses in the lungs, liver, and pancreas. Despite the initial aggressive disease course and involvement of organs at risk, the patient experienced spontaneous regression and lesion disappearance following smoking cessation without chemotherapy. A literature review revealed a distinct subset of MS-LCH that can be managed by smoking cessation and careful observation through follow-up imaging. This suggests that careful observation through follow-up imaging may be a reasonable alternative to chemotherapy in select adult cases of MS-LCH.