Epidemiologic aspects of seborrheic keratoses

Epidemiologic aspects of seborrheic keratoses Seborrheic keratoses (SK) are very common cutaneous tumors with unperceived onset occurring on almost any site of the body, especially in populations with fair complexion. In Greece, there is skin type ‡ 3 predominance in the population at large. Results were obtained from two independent series. In our region, the bulk of primary skin care is offered by dermatologists rather than general practitioners. It is acknowledged that selection bias of such an outpatient-based study cannot be completely avoided. At first we analyzed eight-year cross-sectional outpatient data (1995–2002) of an urban area general state hospital dermatologic teaching clinic regarding detection rates of SK as primary lesions. These are associated with a recently increased disease activity of a potentially overlooked condition and the fear of skin cancer and melanoma-related health education. The diagnosis was based on clinical findings. The overall denominator and reference population consisted of 50,237 self-referred Greek dermatologic outpatients, aged from 35 days to 96 years, consecutively examined by dermatologists, males 20,909 (41.6%) and females 29,328 (58.4%) (Table 1). All cases entered in the study were first time referrals. Mantel–Haenszel Chisquare stratified analysis was used to compare detection rates by age and gender without confounding effects. Age ranged widely: median age was 66 years for men (range, 27–89) and 64 years for women (range, 15–92). In accordance with classic opinions, there was no difference by gender in the overall relative prevalence (SK, n = 1131, 22.5&), and this also occurred in all but one the age groups indicating a parallel natural course (Table 1). Disease activity as reflected by detection rates in both sexes displayed three distinct periods by age: (1) Up to 45 years, characterized by much lower than the average rates. (2) From 46 up to 70 years in males and 75 years in females, characterized by a gradual increment by age of already high rates who eventually reached peak prevalence. It is conceivable that there is a little tendency to spontaneous disappearance, whereas new lesions may continue to appear for many years. (3) Thereafter diagnoses declined, probably because the disease was neglected (Table 1). In British and Australian studies, a female preponderance was reported under the age of 40 years. In our series, during the low prevalence period (up to 45 years) although women exceeded men 1.4 times this difference did not reach significance. The significant difference of the 71–75 years age group reflects the more protracted aesthetic concerns in women (Table 1). Irrespective of the presenting complaint, in a second series (n = 787) of consecutively examined, self-referred dermatologic outpatients there were 180 cases of SK (22.9%) and associations with body mass index (BMI) for obesity and skin type were investigated. BMI did not differ between SK cases and non-SK cases (mean ± SEM, unpaired t-test) ([n = 180, 26.98 ± 0.32 and n = 605, 26.78 ± 0.21). SK was also an equally neglected condition with the average of non-SK cases, as perceived disease duration did not differ: [mean ± SEM; n = 180, 5.04 ± 0.6 years (range, 0.0–40 years) vs. n = 597, 4.95 ± 0.26 (range, 0.0–65 years)]. This event in conjunction with the fact that SK as primary lesions accounted for 50% of patients (n = 90) provides evidence for a less neglected condition than believed. Skin type was more fair in SK patients (n = 180, 2.7 ± 0.05 and n = 602, 2.85 ± 0.03, P = 0.01). Lesions were localized on the face (40.4%), multiple sites (30.3%), trunk (20.2%), neck (4.5%), and lower limbs (4.5%).