Our data describe for the first time the presence of elevated IL-7 levels in sera of male patients affected by solid tumors, in fact the only data available in literature, concerning IL-7 serum levels in patients affected by solid tumors are related to gynecologic cancers [27]–[29], while elevated serum IL-7 levels were previously detected in other pathologies with bony involvement, such as multiple myeloma [19], rheumatoid arthritis [30] and systemic juvenile rheumatoid arthritis [31]. Here, IL7 is linked to juvenile idiopathic arthritis.