Giant rapidly involuting congenital hemangioma in a neonate: a case report.

This case report presents a rare instance of a giant rapidly involuting congenital hemangioma (RICH) in a neonate. Prenatal ultrasound identified a placenta-like lesion on the right lower limb. Postnatally, a massive, dark purple tumor was observed. Imaging confirmed the diagnosis of RICH with no deep tissue involvement. The lesion underwent complete spontaneous involution within the first year of life without intervention, accompanied by transient thrombocytosis and ulceration during regression. This case demonstrates that even exceptionally large RICH lesions follow the classic, rapid involuting course. It underscores the importance of recognizing characteristic clinical and radiological features to adopt an active observation strategy, thereby avoiding unnecessary invasive treatments. The report highlights the roles of multidisciplinary management and long-term follow-up in ensuring optimal outcomes.