Leser-Trelat sign in metastasized malignant melanoma.

The Leser-Trelat sign is defined as the association of multiple, eruptive seborrheic keratoses with an internal malignancy of a usually advanced stage. We report the case of malignant melanoma in an 82-year-old man covered with hundreds of greyish-dark seborrheic keratoses resembling a Christmas tree pattern, who was diagnosed with metastasized malignant melanoma involving the parotid gland and lymph nodes. Though the pathogenesis of Leser-Trelat sign is still unknown, spontaneous regression of the seborrheic keratoses following tumor reduction described in some cases argues for a paraneoplastic origin of this highly instructive clinical entity. Physicians should consider a workup for internal malignancy in patients presenting with multiple eruptive seborrheic keratoses.