Thus, immunostaining for CD138, CK, desmin, vimentin, S-100, and HMB45 were requested and the results were compatible with the final diagnosis of amelanotic plasma melanoma.<h4>Conclusion</h4>It is crucial to consider melanoma as one of the differential diagnoses of a tumor with plasmacytoid feature and CD138 positive staining as it can mimic multiple myeloma as demonstrated in this case report. This evidence concerns the gene SDC1 and plasma cell myeloma.