Histology of a patient with mixed histiocytosis. LCH and ECD lesions were present but distinguishable in the same biopsy from a patient with mixed histiocytosis. This sample (patient 8) contained (A) typical LCH as well as (B) ECD infiltration (HandE stain, original magnification ×200). On serial sections, immunohistochemistry showed (C) strong CD1a staining contrasting with (D) strong CD68 staining in distinct areas (original magnification ×40).