The relation between seborrheic keratoses and malignant solid tumours. A case-control study.

In order to establish whether or not here is an association between cancer and intense growth of seborrheic keratosis, the so-called Leser-Trelat sign, we conducted a case control study in which the number and features of seborrheic keratosis in 82 patients with recent solid tumours, were compared with 82 age- and sex-matched controls. Neither numbers nor features of seborrheic keratosis differed significantly in patients and controls. Eruptive seborrheic keratosis was noted in only one patient and one control. This study showed that solid malignancies are not generally associated with an increase in the number or size of seborrheic keratosis lesions, thus suggesting that they are not controlled by a hypothetical secretion of growth factors by tumours. Our results suggest that Leser-Trelat is either a coincidence, or at most a very rare sign of unusual types of cancer. We also showed that multiple cherry angiomas, previously reported to be a paraneoplastic sign, are not regularly associated with solid tumours.