Unusual presentation of Erdheim-Chester disease in a child with acute lymphoblastic leukemia

Table 2 Differential diagnoses of Erdheim-Chester disease

Radiologic differential diagnoses
With osteosclerotic lesions	Renal osteodystrophy, Pagets disease, myelofibrosis, osteoblastic metastases, chronic osteomyelitis, metabolic bone disorders
With osteolytic lesions in children	Langerhans cell histiocytosis, infection, metastatic neuroblastoma
Histologic
Langerhans cell histiocytosis	Positive for S100, CD1a, and Langerin
Rosai-Dorfman disease	Histiocytes show emperipolesis; positive for S100 and CD68; negative for CD1a, and Langerin
Juvenile xanthogranuloma	Lack characteristic radiologic features of ECD; positive for factor XIIIa, CD68, CD163, fascin, and CD14, negative for CD1a, S100, and Langerin
Solitary/multicentric reticulohistiocytoma	Lack characteristic radiologic features of ECD; positive for factor XIIIa, CD68, CD163, fascin, and CD14; negative for CD1a, S100, and Langerin

ECD: Erdheim-Chester disease.