<prompt> A 70 yrs male patient has single well defined lytic lesion of skull. The patient had no other complaint and urine examination had no abnormality. What is the most likely diagnosis?L.C.HLocalized myeloproliferative disorderGeneralized myeloproliferative disorderTumor of osteoblasts  <response>: Langerhanss cell histiocytosis X-ray- well-demarcated lytic lesion, hole within a hole. ME - Tennis-racket inclusion bodies and Birbeck granules Plasmacytoma Localized myeloproliferative disorder, does not present with lytic lesions in the skull. Generalized myeloproliferative disorder is multiple myeloma which presents with characteristic punched-out lytic lesions in the skull. Serum or urinary electrophoresis measures immunoglobulins over-produced by the plasma cells. Lytic lesions of skull: M- Metastasis E- EGeosinophilic granuloma L- LCHLymphoma T-T.B H-Hyperparathyroidism O- Osteomyelitis R- Radiotherapy M- MMMultiple myeloma E- Epidermoid 