<prompt> Two year old child presented with multiple bone defects and seborrheic dermatitis. Diagnosis ?Eosinophilic granulomaHand schuller Christian diseaseLetterer siwe diseaseHashimoto pritzker disease  <response>: Letterer Siwe disease - - child- 2yrs - generalised systemic involvement - Boneskinhepatosplenomgaly with lymphadenopathy -Skin- mc manifestation is seborrheic dermatitis. Current Classification Single-system Disease - either Localized single site or Multiple siteMultisystem Disease - Low-risk group Disseminated disease with involvement of low-risk organs skin, bone, lymphnode, pituitary or High-risk group Disseminated disease with involvement of one or more of the high-risk organshematopoietic system, lungs, liver, and spleen 