IL10 and mucoepidermoid carcinoma: In patients with cancer, IgG4-positive cells may occur as an inflammatory response, a finding that raises the suspicion of MEC-mediated IgG4 production.[7,16] The mechanism behind this inflammatory response is thought to be cytokine-mediated, involving interleukin-10 and transforming growth factor β, both of which induce increased IgG4-positive cells and fibrosis.[17] Tian et al[5] reported several cases of sclerosing MEC with surrounding IgG4-positive cells, but none of their patients had IgG4-RD in other organs or in the nontumoral salivary gland.