Langerhans cell histiocytosis is essentially a pediatric disorder with a large spectrum encompassing focal lytic osseous eosinophilic granuloma, chronic multifocal Hand-Schuller-Christian lesions, and fulminant disseminated Letterer-Siwe syndrome. However, adult involvement is not uncommon. The authors present a case of multifocal Langerhans cell histiocytosis in a 47-year-old woman. The PET/CT-depicted infiltrative features of soft tissue and osseous pelvic lesions with obstructive uropathy are unusual for this disease.