Two year old child presented with multiple bone defects and seborrheic dermatitis. Diagnosis ?

Letterer Siwe disease - - child- <2yrs - generalised systemic involvement - Bone>skin>hepatosplenomgaly 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 organs(hematopoietic system, lungs, liver, and spleen)