Seborrheic keratosis is a benign skin tumors that arise in most older people, about 20% of the population and are usually absent or rare in people with middle age. Seborrheic keratosis has many clinical manifestations can be seen, and seborrheic keratosis is formed of proliferation of epidermal cells of the skin. Seborrheic keratoses can appear in many forms lesions, lesions can be one or many types of lesions or multiple.
Although there is no specific etiologic factors that can be known, seborrheic keratosis often appear on sun-exposed areas, especially on the neck and face, as well as the extremities.
Global or international, seborrheic keratosis is a benign tumor of the skin most widely among the population in the United States. Frequency figures for the emergence of seborrheic keratoses appear to increase with increasing age of the person
The exact cause of seborrheic keratoses is unknown. Others have suggested that genetic factors play an important role. Some cases decreased by autosomal dominant. Some say that chronic exposure to sunlight is the cause. There are also saying that the suspected virus infection based on clinical picture wart. DNA of human papilloma virus obtained in 40 cases of seborrheic keratosis genital and 42 of the 55 cases of non-genital seborrheic keratosis (76%)
In 1963, Tindall and Smith examined the population of individuals who are older than 64 years in North Carolina and get the result that 88% of the population has at least at least one seborrheic keratosis lesions. In this study, seborrheic keratosis was found in 38% of white women and 54% in white men, and about 61% in black men and about 10% more in black women.
In 1965 Young examine 222 people who live in nursing anti Orthodox Jewish in New York and found that 29.3% of men and 37.9% of women had a seborrheic keratosis lesions.
Seborrheic keratoses are often obtained in middle age to old and may appear first in adolescence.
Epidermal Growth Factor (EGF) or its receptor, has been shown to be involved in the formation of seborrheic keratosis. No significant differences of immunoreactive growth hormone receptor expression in epidermal keratinocytes in normal and seborrheic keratosis.
A high frequency of mutations in the gene encoding role in the tyrosine kinase receptor FGFR3 (fibroblast growth factor receptor 3) have been found in several types of seborrheic keratosis. This is the reason that the factor gene into the base in the pathogenesis of seborrheic keratosis. FGFR3 contained in transmembrane receptor tyrosine kinases that participate in signal transduction gives to the regulation of growth, differentiation, migration and cell healing. FGFR3 mutation present in 40% of seborrheic keratoses hyperkeratosis, acanthosis 40% seborrheic keratoses, seborrheic keratoses and 85% adenoids.
Seborrheic keratosis has many degrees of pigmentation. In pigmented seborrheic keratosis, proliferation of keratinocytes stimulate the activation of the melanocytes surrounding the melanocyte-stimulating secreting cytokines. Endothelin-1 has multiple simulation effect on DNA synthesis and melanization in human melanocytes and has been shown to be involved sabagai one important role in the formation of hyperpigmentation in seborrheic keratosis.