Role of PET/CT in congenital histiocytosis.

Congenital Langerhans cell histiocytosis (LCH) is a rare, but often severe, form of LCH. Although a more benign single-system congenital LCH has been described, most cases present as multisystem disease with poorer prognosis and are often treated with systemic chemotherapy. Imaging plays a central role in diagnosis, initial staging and assessment of treatment response. PET/CT is increasingly utilized for pediatric LCH. We report a unique case with PET/CT used as an imaging tool in staging and evaluating treatment response in congenital multisystem LCH.