This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cells of epidermis, Subject name: Dental
Two year old child presented with multiple bone defects and seborrheic dermatitis. Diagnosis ? 
Select and explain. 
A. Eosinophilic granuloma, B. Hand schuller Christian disease, C. Letterer siwe disease, D. Hashimoto pritzker disease
C: Letterer siwe disease
Answer: C: Letterer siwe disease 
Explanation: 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)