Langerhans cell histiocytosis (LCH) lesion histology. 

A: LCH lesion demonstrating foamy histiocytes with grooved nuclei on a polymorphous inflammatory infiltrate background composed of abundant eosinophils, lymphocytes, neutrophils. B: CD207+ (langerin) antibody stain on an LCH lesion demonstrating strong positivity with associated multinucleated giant cells from an LCH lesion. C:Juvenile xanthogranuloma lesion demonstrating multinucleated Touton giant cells and xanthomatous cells in background. D: Biopsy of an enlarged lymph node from a child with significant bilateral cervical lymphadenopathy. This image demonstrates emperipolesis, a characteristic of Rosai-Dorfaman disease, where viable lymphocytes traffic through with histiocytes (clear background). E: Bone marrow aspirate from a patient with hemophagocytic lymphohistiocytosis, demonstrating characteristic vacuolated macrophages engulfing red blood cells (hemophagocytosis) and lymphocytes.

Source: Kline MW. Rudolph's Pediatrics, 23e; 2018.