Introduction Histocytosis X is a spectrum of diseases of the reticuloendothelial system that includes eosinophilic granuloma usually a single self-limited lesion found in younger patients (first 3 decades of life) Hand-Schuller-Christian disease has both bone and visceral lesions classic triad (< 25%) includes exophthalmus diabetes insipidus lytic skull lesions Letterer-Siwe disease fatal form that occurs in young patients Presentation Symptoms pain and swelling Imaging Radiographs well defined intramedullay lytic or "punched-out" lesion cortex may be destroyed may have periosteal reaction vertebra plana in spine MRI may show a soft tissue mass bone scan is warm to hot Electronmicroscopy birbeck granules seen inside Langerhan's cells Histology Characteristic histology shows Langerhan's cells mononuclear histiocyte-like cells with oval nuclei with well-defined round or oval cytoplasm. a prominent nuclear groove (coffee bean nuclei) can be seen in most of the nuclei pink cytoplasm (depends on stain) lipid-laden foam cells with nuclear debris a mixture of inflammatory cells lack of nuclear atypia and atypical mitoses differentiates this condition from malignant conditions such as Ewings sarcoma, lymphoma of bone, and metastatic neuroblastoma, which may look similar based on the round cells alone Treatment Nonoperative observation alone a self-limited process and it is reasonable to treat with observation alone low dose irradiation (600-800 cGy) effective for most lesions indicated for lesions in the spine that compromise stability and neurologic status Operative curettage and bone grafting indicated for lesions that endanger the articular surface or are a risk for impending fractures Differentials and Groups Destructive lesion in young patients Multiple lesions in young patients (1) Treatment is Observation alone (2) Eosinophilic granuloma • • • Osteomyelitis • Osteosarcoma • Ewing's sarcoma • Desmoplastic fibroma • Lymphoma • • Leukemia • • Fibrous dysplasia • • Enchondroma / Olliers / Marfucci's • • Osteochondroma / MHE • • Hemangioendothelioma • NOF / Jaffe-Campanacci syndrome • • Paget's • ASSUMPTIONS: (1) Younger patient is < 40 yrs; (2) assuming aymptomatic and no impending fracture Ibank Location Xray Xray CT B. Scan MRI MRI Histo (1) Case A Spine Case B Radius Case C Humerus Case D Femur, 13 yo female Case E Skull (1) - histology does not always correspond to clinical case