Baby with recurrent infection of ear & discharge & seborrheic dermatitis with hepatosplenomegaly with cystic skull lesions. Diagnosis is

In Langerhans Cell Histiocytosis,the most common involvement is of the skeleton(80%).Bone lesions can be single or multiple affecting skull bones,long bones,veebrae,mastoid and mandible.The lesions may be painless or present with pain and local swelling;X rays show sharp lytic lesions.Clinical manifestation includes veebral collapse and spinal compression,pathological fractures in long bones,chronic draining ears and early eruption of teeth.Other manifestations include seborrhoeic skin rash on scalp and back(60%),lymphadenopathy(33%),hepatosplenomegaly(20%),tachypnoea,air leaks,parenchymal lung infiltrates(15%),jaundice,abdominal distension,neurodegenerative symptoms and features of malabsorption.There may also be exophthalmos,pituitary dysfunction producing growth retardation and/or diabetes insipidus,fever,weight loss,malaise,failure to thrive,liver dysfunction,anemia and thrombocytopenia . Image : skull x-ray showing lytic leasions in Langerhans cell histiocytosis . Reference:Essential pediatrics-Ghai,8th edition,page no:620,621.