Paraneoplastic Dermatoses: A Clue for Underlying Malignancies.

Paraneoplastic dermatoses (PDs) belong to a group of rare and polymorphous dermatoses, and they can often be the first sign of underlying malignancies. Therefore, dermatologists should be able to identify skin features to identify earlier underlying neoplasms. Indeed, lack of familiarity with cutaneous clues of internal malignancies can lead to a delay in the diagnosis and an impairment of the prognosis of the patients. In this review, we described several PDs, including more common and rarer PD. Indeed, while malignant acanthosis nigricans, characterized by velvety, verrucous, hyperpigmented plaques that usually affect intertriginous areas, is a well-known PD, necrolytic migratory erythema is usually misdiagnosed because its clinical features can be similar to seborrheic dermatitis. Furthermore, we focused on two paradigmatic PDs, namely paraneoplastic autoimmune multiorgan syndrome (PAMS) and paraneoplastic dermatomyositis. Indeed, PAMS represents a paradigmatic form of obligate PD, which is always associated with an underlying neoplasm, while paraneoplastic dermatomyositis belongs to the facultative PD, which can be associated with neoplasia in a variable percentage of cases.