<prompt> Localised langerhans cells histiocytosis affecting head neck is -Letterer-siwe diseasePulmonary langerhans cell histiocytosisHand-schuller-christian diseaseEosinophilic granuloma  <response>: Unifocal and multifocal unisystem Langerhans cell histiocytosiseosinophilic granulomais characterised by proliferation of Langerhans cells admixed with variable number of eosinophils , lymphocytes , plasma cell, and neutrophils .Eosinophils are usually , but not always a prominent component of the infiltrate .It typically arises within the medullary cavities of bones, most commonly the calvarium, ribs and femur. ref: Robbins pathologic basis of disease ; 8th edition ; pg 632 