Acral manifestations of paraneoplastic and collagen vascular diseases.

The skin often signals a number of systemic disease, making skin findings of paramount significance. Paraneoplastic diseases and collagen vascular diseases are vitally important illnesses. Paraneoplastic diseases and collagen vascular diseases may also occur with many different acral skin findings. Paraneoplastic skin diseases, associated with some cancers, are by definition nonmalignant skin disorders. These diseases can occur before, simultaneously, or after the diagnosis of cancer. Acral paraneoplastic diseases include acanthosis nigricans maligna, acquired pachydermatoglyphia, acrokeratosis paraneoplastica, palmoplantar keratoderma, and paraneoplastic nail disorders. Collagen vascular diseases include the acral skin findings of lupus erythematosus, scleroderma, dermatomyositis, and rheumatoid arthritis. Any acral skin finding may be encountered as the first finding of an undiagnosed malignancy or collagen vascular diseases. The role of the dermatologist is significant for often being the first physician to suspect a malignancy or collagen vascular disease.