Acquired cutis laxa (ACL) is a rare connective tissue disorder that affects the skin elastic fibers, resulting in the loss of elasticity. In 50% of cases, this condition is associated with other diseases, particularly plasma-cell dyscrasias. This report describes a case of ACL with unusual clinical and histopathological characteristics. A 29-year-old man presented with diffuse erythematous plaques that had first appeared 5 months previously. Examination revealed multiple flaccid erythematous plaques on his trunk, neck, and skinfolds. Immunophenotyping of bone marrow aspirate revealed 7% of monoclonal plasma cells with lambda light chain expression. Skin biopsy histology revealed foci of interstitial granulomatous reaction. Weigert stain showed a loss of elastic fibers in the dermis, areas with thickened fibers and elastophagocytosis. Immunohistochemistry was positive for CD68. The cutaneous findings enabled an early diagnosis of IgG lambda monoclonal gammopathy to be made. Microscopic examination revealed an interstitial granulomatous reaction and severe alterations in the elastic fibers that varied in intensity in the different biopsies. Curiously, little has been mentioned in the literature regarding the presence of an interstitial granulomatous reaction in ACL. It is our belief that this reaction is secondary to the degenerative process of the elastic fibers.