A child presents with painless bilateral mandibular enlargement over the past year. Calcium and phosphate levels are NORMAL. T3 and T4 are NORMAL. Histopathology reveals GIANT CELLS. What is the most likely diagnosis?

Cherubism (A) is the correct diagnosis. Cherubism is a rare autosomal dominant condition presenting in early childhood (2-7 years) with bilateral, painless jaw enlargement — classically both mandible and maxilla. Histologically it shows giant cells in a fibrovascular stroma (identical to central giant cell granuloma). KEY distinguishing features:
• BILATERAL involvement (vs. CGCG which is usually unilateral)
• NORMAL calcium, phosphate, T3/T4 (rules out hyperparathyroidism and thyroid disease)
• Brown Tumor (B): associated with ELEVATED PTH, LOW calcium, LOW phosphate (hyperparathyroidism). Labs abnormal!
• CGCG (C): usually UNILATERAL, not bilateral.
• Key rule: bilateral jaw enlargement in a child + normal labs + giant cells = Cherubism.