Diffuse plane normolipemic xanthomatosis (DPNX) is a rare, non-inherited disease that is often associated with systemic diseases, mainly malignant hematological (especially multiple myeloma) or lymph proliferative disorders. The DPNX can precede the appearance of such conditions by several years, so careful follow-up and periodic laboratory examinations are recommended even for patients that seemed to have no underlying disease. We describe a case associated with monoclonal gammopathy. This case shows that dermatological lesions can be the first manifestation of important hematological diseases and so physicians should be familiarized with this entity.