PDCD1 and Miyoshi myopathy: The aim of this study was to analyse PD-1/PD-L1 expression in the BM niche of patients with MGUS, asymptomatic SMM or active disease, including MMD and MMR patients, and to further investigate a possible correlation with both clinical parameters, as cytogenetic abnormalities and bone disease, and serum levels of soluble factors involved in MM pathophysiology and immune response.