What is the role of sebocytes in the development of sebaceous hyperplasia?

Updated: Oct 05, 2020
  • Author: David T Robles, MD, PhD, FAAD; Chief Editor: William D James, MD  more...
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Answer

Sebocytes contain androgen-metabolizing enzymes, including 5-alpha-reductase type I, 3-beta-hydroxysteroid dehydrogenase, and 17-beta-hydroxysteroid dehydrogenase type II. These enzymes metabolize relatively weak circulating androgens, such as dehydroepiandrosterone-sulfate, into the more potent androgens, such as dihydrotestosterone. These, in turn, bind to receptors within the sebocytes, causing an increase in the size and metabolic rate of the sebaceous gland. Studies have shown that the activity of 5-alpha-reductase is higher in the scalp and facial skin than in other areas, so that testosterone and dihydrotestosterone stimulate more sebaceous gland proliferation in these areas. Estrogens, on the other hand, have been found to decrease sebaceous gland secretion.

In the perinatal period, the sebaceous glands are initially large and are likely responsible for the production of vernix caseosa often seen in newborns. The activity and size of the sebaceous glands regress shortly after birth, due to withdrawal of maternal hormones, and remain small throughout infancy and childhood. At puberty, sebaceous glands enlarge and become increasingly active due to increased production of androgens, reaching their maximum by the third decade of life. As androgen levels decrease with advancing age, the sebocyte turnover begins to slow down.

This decrease in cellular turnover results in crowding of primitive sebocytes within the gland, resulting in enlargement. In contrast to normal sebocytes that are engorged with lipid, the hyperplastic sebaceous glands contain small undifferentiated sebocytes with large nuclei and scant cytoplasmic lipid. [16, 17, 18]


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