Multifocal eosinophilic granuloma with femoral epiphyseal lesion mimicking an aneurysmal bone cyst.

Eosinophilic granuloma (EG) is a rare benign tumor-like disorder characterized by abnormal proliferation Langerhans cells. EG frequently presents as a solitary lesion in the axial skeleton and diaphysis long bones. Here we present the case of a 14-year-old male with multifocal EG with a lesion located in the femoral epiphysis mimicking an aneurysmal bone cyst that presented a diagnostic challenge. While the initial presentation of EG patients may appear uncommon, its overlapping features with other benign and malignant etiologies highlight the importance of increased awareness of this condition, as well as the need for an experienced multidisciplinary team in its diagnosis and treatment.