The diagnosis of ECD was made by characteristic histopathologic features in addition to clinical-radiographic features and the typical immunoprofile (positive for cluster of differentiation 68 [CD68], CD163, and p16; negative for CD1a and S-100).
Diagnosis of ECD involves the analysis of histiocytes in tissue biopsies: these are typically foamy and CD68+ CD1a- in ECD, whereas in Langerhans cell histiocytosis (LCH) they are CD68+ CD1a+.