Contrast-enhanced sonography in the diagnosis of Langerhans cell hyperplasia in children with isolated liver involvement: A case report and review of the literature.

RATIONALE: Isolated hepatic involvement of Langerhans cell histiocytosis (LCH) in the pediatric population is an exceedingly rare condition. Its clinical presentation is nonspecific, and its imaging features frequently overlap with those of other hepatic focal lesions, rendering preoperative diagnosis particularly challenging. PATIENT CONCERNS: An 11-year-old girl presented with a chief complaint of intermittent abdominal pain. DIAGNOSES: Enhanced computed tomography and magnetic resonance imaging revealed multiple liver nodules. A characteristic imaging pattern was observed: during the portal venous and delayed phases, the periphery of the lesions exhibited a "wash-in and wash-out" enhancement pattern, while the central areas remained non-enhancing throughout all phases. This imaging finding provided a crucial diagnostic clue. The diagnosis of LCH was ultimately confirmed by liver biopsy, supplemented by electron microscopy and immunohistochemistry. Systemic evaluation verified isolated hepatic involvement. INTERVENTIONS: The patient received immunosuppressant therapy combined with prednisone and vindesine-based combination chemotherapy. OUTCOMES: The patient was treated with immunosuppressant therapy and combination chemotherapy. Follow-up at 6 months indicated a favorable recovery. LESSONS: This case illustrates that contrast-enhanced ultrasound can effectively delineate the unique hemodynamic characteristics of hepatic LCH lesions, serving as a valuable supplement to conventional cross-sectional imaging. In the differential diagnosis of focal liver lesions in children, particularly when there is clinical suspicion for LCH, increased recognition of these specific contrast-enhanced ultrasound features is crucial. This awareness can help prevent diagnostic delays and guide targeted pathological sampling.