summary Eosinophilic Granulomas are self-limiting benign histiocytic lesions that can occur in isolation or as a part of 2 systemic syndromes: Hand-Schuller-Christian (HSC) disease and Letterer-Siwe disease (LSD). Isolated lesions typically present with pain in the thoracic spine or long bones in patients < 20 years of age. HSC presents with diabetes insipidus and exophthalmos, while LSD is fatal in early childhood. Diagnosis is made with biopsy showing mononuclear histiocyte-like cells with oval nuclei with well-defined round cytoplasm with electron microscopy revealing Birbeck granules seen inside Langerhan's cells. Treatment for isolated Eosinophilic Granulomasis is usually observation with pain management as the lesions typically resolve over time. Surgical management is indicated for lesions associated with impending fracture. Treatment for HSC and LSD is focused on the medical management of the syndrome. Epidemiology Demographics most commonly occurs in children (80% of afflicted < 20 years of age) HSC disease presents in children > 3 years of age LSD occurs in children < 3 years of age Male to female ratio of 2:1 Anatomic location eosinophilic granuloma login to view 3 more bullets HSC login to view 3 more bullets Etiology A spectrum of diseases of the reticuloendothelial system with one of three general presentations Eosinophilic granuloma (EG) login to view 1 more bullet Hand-Schuller-Christian disease (HSC) login to view 2 more bullets Letterer-Siwe disease (LSD) login to view 1 more bullet Genetics no clear genetic pattern of inheritance or locus has been determined Presentation Symptoms skeletal involvement login to view 2 more bullets vertebral involvement login to view 3 more bullets HSC login to view 7 more bullets Imaging Radiographs general login to view 2 more bullets diaphyseal lesions login to view 3 more bullets metaphyseal lesions login to view 2 more bullets spinal lesions login to view 2 more bullets cranial involvement login to view 1 more bullet MRI may show a soft tissue mass adjacent to boney lesions Bone scan generally shows increased uptake in the region of boney lesion Whole Body PET/CT indicated as part of staging if multifocal disease confirmed login to view 1 more bullet Studies Histology Langerhan's cells login to view 6 more bullets mixture of inflammatory cells also present giant cells are present lack of nuclear atypia and atypical mitoses login to view 1 more bullet Differential Eosinophilic Granuloma Differential Destructive lesion in young patients Multiple lesions in young patients Treatment is Observation alone Eosinophilic granuloma o Osteomyelitis o Osteosarcoma o Ewing's sarcoma o Desmoplastic fibroma o Lymphoma o o Leukemia o o Fibrous dysplasia o o Enchondroma / Olliers / Maffucci's o o Osteochondroma / MHE o o Hemangioendothelioma o NOF /Jaffe-Campanacci syndrome o o Paget's o Treatment Nonoperative observation alone login to view 2 more bullets bracing login to view 5 more bullets low dose irradiation (600-800 cGy) login to view 5 more bullets chemotherapy login to view 4 more bullets corticosteroid injection login to view 3 more bullets Operative curettage and bone grafting login to view 2 more bullets spinal deformity correction login to view 3 more bullets Prognosis EG isolated involvement generally treatable with local management spine lesions can spontaneously resolve HSC prognosis depends on response to chemotherapy worsening prognosis with increasing extraskeletal involvement LSD generally fatal in children < 3 years of age