Phospholamban is involved in the regulation of the activity and storage of calcium in cardiac muscle. Several mutations have been identified in thePLNgene causing cardiac disease associated with arrhythmogenic and dilated cardiomyopathy. The patho-mechanism underlyingPLNmutations is not fully understood and a specific therapy is not yet available.PLNmutated patients have been deeply investigated in cardiac muscle, but very little is known about the effect ofPLNmutations in skeletal muscle. In this study, we investigated both histological and functional features in skeletal muscle tissue and muscle-derived myoblasts from an Italian patient carrying theArg14delmutation inPLN. The patient has a cardiac phenotype, but he also reported lower limb fatigability, cramps and fasciculations. The evaluation of a skeletal muscle biopsy showed histological, immunohistochemical and ultrastructural alterations. In particular, we detected an increase in the number of centronucleated fibers and a reduction in the fiber cross sectional area, an alteration in p62, LC3 and VCP proteins and the formation of perinuclear aggresomes. Furthermore, the patient’s myoblasts showed a greater propensity to form aggresomes, even more marked after proteasome inhibition compared with control cells. Further genetic and functional studies are necessary to understand whether a definition of PLN myopathy, or cardiomyopathyplus, can be introduced for selected cases with clinical evidence of skeletal muscle involvement. Including skeletal muscle examination in the diagnostic process ofPLN-mutated patients can help clarify this issue.