Sebaceous Hyperplasia

Updated: Jun 22, 2017
  • Author: David T Robles, MD, PhD; Chief Editor: William D James, MD  more...
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Overview

Background

Sebaceous hyperplasia is a common, benign condition of sebaceous glands in adults of middle age or older. Lesions can be single or multiple and manifest as yellowish, soft, small papules on the face (particularly nose, cheeks, and forehead). Sebaceous hyperplasia occasionally also occurs on the chest, [1] areola, [2] mouth, [3] scrotum, [4] foreskin, [5] shaft of penis, [6] and vulva. [7, 8, 9] Rarely reported variants have included a giant form, [10] a linear [11] or zosteriform arrangement, a diffuse form, a nevoid form, [12] and a familial form. Lesions of sebaceous hyperplasia are benign, with no known potential for malignant transformation, but they may be associated with nonmelanoma skin cancer in transplantation patients. [13, 14, 15]

Typical facial papules appear in middle age, are larger than lesions on the areola or mouth, and display a central dell that corresponds to a central follicular infundibular ostium.

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Pathophysiology

Sebaceous glands are found throughout the skin except on the palms and soles. They exist as a component of the pilosebaceous unit or, less frequently, open directly to the epithelial surface in areas of modified skin, including the lips and buccal mucosa (as Fordyce spots), glans penis or clitoris (as Tyson glands), areolae (as Montgomery glands), and eyelids (as meibomian glands). The largest and greatest numbers of sebaceous glands are found on the face, chest, back, and the upper outer arms.

These holocrine glands are composed of acini attached to a common excretory duct. The life cycle of a sebocyte, the cells that form the sebaceous gland, begins at the periphery of the gland in the highly mitotic basal cell layer. As sebocytes differentiate and mature, they accumulate increasing amounts of lipid and migrate toward the central excretory duct. The mature sebocytes complete their life cycle at the central duct and disintegrate, releasing their lipid contents as sebum. The turnover time from sebocyte production to disintegration is approximately 1 month.

Sebaceous glands are highly androgen sensitive, and, although the number of sebaceous glands remains approximately the same throughout life, their activity and size vary according to age and circulating hormone levels. Together, sebaceous and sweat glands account for the vast majority of androgen metabolism in the skin.

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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Epidemiology

Frequency

Sebaceous hyperplasia is a common skin finding in aging adults, reported to occur in approximately 1% of the healthy US population. However, the prevalence of sebaceous hyperplasia has been reported to be as high as 10-16% in patients receiving long-term immunosuppression with cyclosporin A. [19, 20, 21]

Sex

The difference in prevalence between men and women is unknown.

Age

Sebaceous hyperplasia is common in newborns. [22] Of 1000 consecutive neonates examined in an Iranian prospective cohort study, 43.7% had sebaceous hyperplasia. [23]

Typical facial papules begin to appear in middle age (usually fifth or sixth decade) and continue to appear into later life.

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Prognosis

Sebaceous hyperplasia has no direct association with malignant degeneration and is not a cause of morbidity beyond cosmetic concerns. Sebaceous hyperplasia has been reported in association with internal malignancy in the setting of Muir-Torre syndrome. Muir-Torre syndrome is a rare autosomal dominant disorder in which visceral malignancies, sebaceous neoplasms (eg, sebaceous adenoma, sebaceous carcinoma), and keratoacanthoma coincide. Colon cancer is the leading internal malignancy associated with Muir-Torre syndrome, followed by hematologic malignancies. [24] Sebaceous hyperplasia alone does not signify a predisposition to cancer or represent a sign of Muir-Torre syndrome.

One study reported that 29.9% of patients with a renal transplant had sebaceous hyperplasia, and that 45.7% of these patients had a history of nonmelanoma skin cancer (NMSC), compared with 7.3% of patients without sebaceous hyperplasia. In this population, the association of NMSC with sebaceous hyperplasia remained significant after correction of factors such as age, sex, skin type, and duration since transplantation. [14] Thus, the presence of sebaceous hyperplasias in the setting of renal transplantation may serve as a marker for an elevated risk of NMSC.

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Patient Education

Patients should be educated that sebaceous hyperplasias are benign and that treatment is primarily for cosmetic benefit. 

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