Bone involvement in Hodgkin lymphoma (HL) is rare. The differential diagnosis between HL bone localization and other malignant or benign skeletal diseases is challenging. We report the case of a girl affected by classic HL, initially staged IVA because of supradiaphragmatic lymph nodes and skeletal involvement. After 6 ABVD (adriamycin, bleomycin, vinblastine, dacarbazine) cycles, positron emission tomography (PET) showed a complete metabolic response of the nodal localizations and a persistent, high metabolic activity of bone lesions. Salvage treatment followed by autologous stem cell transplant was carried out. After the transplant, the bone lesions maintained a high metabolic activity at PET. A targeted bone biopsy led to the diagnosis of a fibrous dysplasia excluding the presence of HL. To our knowledge, the concomitant presence of HL and fibrous dysplasia has not been previously reported. An in-depth evaluation of disease response to frontline treatment with a biopsy of the PET-hypercaptant bone lesions could have avoided overtreatment in this patient.