Volume 26 Number 6 June 1992 Autoantibodies in oral lichen planus tibodies--in a patient with generalized lichen planus. J Korean Med Sci 1987;2:259-62. 23. Camisa C, Allen CM, Brown B, et al. Indirect immuno- fluorescence of oral lichen planus. J Oral Pathol 1986;15:218-20. 24. Nisengard R J, Neiders M. Desquamative lesions of the gingiva. J Periodontol 1981;52:500-10. 25. Medenica M, Lorincz A. Lichen planus: an ultrastructural study. Acta Derm Venereol (Stockh) 1977;57:55-62. 26. Shklar G, Flynn E, Szabo G. Basement membrane alter- ations in oral lichen planus. J InvestDermato11978;70:45- 50. 27. Jungell P. Immunoelectron microscopic study of the base- ment membrane in oral lichen planus. J Cutan Pathol 1990;17:72-6. 28. Sun A, Wu YC. Antimucosal antibodies in recurrent aphthous ulcers. J Formosan Med Assoc 1989;88:122-7. IIIll IIIII Seborrheic keratoses and cancer B. Lindel6f, MD, PhD, B. Sigurgeirsson, MD, and S. Melander Stockholm, Sweden Background: The eruptive appearance of numerous seborrheic keratoses, the sign of Leser- Tr61at, has been regarded as a reliable cutaneous marker of internal malignancy. Objective: We have evaluated the possible association of malignant disease and the sign in 1752 consecutive cases of seborrheic keratoses. Methods: First, the Swedish Cancer Registry was searched for records of malignancies in the study population (1958 to 1984), and the expected number of malignancies was calculated. Second, records of persons with malignancy within 1 year before or after the diagnosis of se- borrheie keratosis were checked for the sign of Leser-Tr61at. Third, a case control study was performed to evaluate the possibility of eruptive seborrheic keratoses among the noncancer patients in the study population. Results: The results showed a slight increased risk of cancer in the study population (relative risk = 1.2; 95% confidence interval = 1.0 to 1.3), mainly because of an increased risk of cu- taneous squamous cell carcinoma. In 62 patients with seborrheic keratose, s, a malignancy (excluding skin) was diagnosed within 1 year before or after the diagnosis of seborrheic kera- tosis. Of these 62 patients, 6 were regarded as possibly having presented with the sign of Leser-Tr61at. For every one of the 62 cases with seborrheic keratosis and malignancy within one year, an age- and sex-matched control patient without cancer was selected from the study population and the records were checked for sudden and eruptive seborrheic keratoses. Among the control patients, five were regarded as possibly having presented with the sign of Leser-Tr61at. Conclusion: This study gives no evidence to support the opinion that eruptive seborrheic keratoses are related to internal cancer risk. (J AM ACAD DERMATOL1992;26:947-50.) The sign of Leser-Tr61at, or eruptive seborrheic keratoses (SK), is considered to be a cutaneous marker for many underlying malignancies] How- ever, the credibility of this skin change as a para- neoplastic sign has been questioned. 2 In this study we have linked details of many patients with SK with From the Department of Dermatology,Karolinska Hospital, Accepted for publication Dec. 20, 1991. Reprint requests: Bernt Lindel6f, MD, Department of Dermatology, Karolinska Hospital, S-t04 01 Stockholm,Sweden. 16/1/35756 Swedish Cancer Registry records to identify those with malignant tumors. Data from persons with malignancy between 1 year before and 1 year after the diagnosis of SK were examined for the sign of Leser-Tr61at. A matched control population without malignancy was also reviewed with regard to the sign. PATIENTS AND METHODS Patients From 1958 to 1983, 1752 cases of SK were diag- nosed at the Department of Dermatology, Karofin- 947