Figure 4.

Patients displaying CXCR4⁺ LCH-cells at diagnosis are more likely to develop LCH at multiple sites and are prone to LCH reactivation. (A) Flow diagram showing the association between CXCR4 expression on LCH-cells in primary LCH lesions with the manifestation of LCH either at a single or at multiple sites at diagnosis (upper row) or during the entire follow-up period (lower row). Note that, poly-ostotic lesions and LCH lesions in multiple organ systems were collectively designated as ‘LCH manifestations at multiple sites’; mono-ostotic lesions and solitary skin, lung or LN lesions were designated as ‘single site LCH manifestation’. Follow-up data were not available from two patients with single-site disease; these patients were designated as single-site lesions in follow-up. (B) Kaplan–Meier analysis showing that none of the 13 of LCH patients in whom the LCH-cells lacked membrane CXCR4 expression reactivated within 10 y after the primary diagnosis. On the contrary, nearly half of the patients (17/41) with CXCR4⁺ LCH-cells at disease onset showed LCH reactivation later in time. Clinical follow-up was incomplete for five patients, who were excluded from the correlation analysis. Clinical follow-up for nine patients was longer than ten years without any event.