eMedicine Specialties > Dermatology > Diseases of the Adnexa

Perforating Folliculitis

Author: Suguru Imaeda, MD, Chief of Dermatology, Yale University Health Services; Chief of Dermatology, West Haven Veterans Affairs Medical Center; Assistant Professor, Department of Dermatology, Yale University School of Medicine
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Updated: Jun 18, 2009

Introduction

Background

Perforating disorders are characterized by transepidermal elimination of altered keratin or dermal connective tissue material. These disorders include perforating folliculitis, Kyrle disease, elastosis perforans serpiginosa, reactive perforating collagenosis, and acquired perforating dermatosis. Cases of overlap are described, and diagnostic criteria are not well-defined for all the entities.¹ Clinically, the lesions are hyperkeratotic to verrucous papules and nodules.

In perforating folliculitis, keratotic follicular papules develop, particularly over extensor surfaces. Microscopically, the disorder is characterized by disruption of the infundibular portion of the follicular wall, with transepidermal (transfollicular) elimination of connective-tissue elements and cellular debris.

Perforating folliculitis may present as an isolated finding, apparently unrelated to other disease states, but also can be associated with chronic renal failure and diabetes mellitus. Perforating folliculitis is closely related, if not identical, to the acquired perforating dermatosis that occurs with chronic renal disease. Kyrle disease (hyperkeratosis follicularis et parafollicularis in cutem penetrans) may simply represent an exaggerated form of perforating folliculitis. In addition, another disorder of transepidermal elimination, elastosis perforans serpiginosa, occasionally displays involvement of follicular units.

Pathophysiology

As in Kyrle disease, the concept of an extrinsic keratin plug penetrating the epidermis generally has been discredited. Abnormally premature keratinization at the expense of proliferation is a possible explanation, as proposed by Carter and Constantine and Tappeiner et al in Kyrle disease.^2,3 A role for fibronectin has been postulated. In addition, a primary alteration of connective tissue or deposition of foreign material within the superficial dermis, with subsequent engulfment and elimination by proliferative follicular epithelium, also is conceivable as a mechanism. Such a response to experimental implantation of foreign material has been described.

In addition, evidence suggests a pathologic role for excessively coiled hairs. Mehregan first proposed that curled hairs within follicular canals may act as springs, penetrating the lateral follicular wall, thereby initiating the process of transepidermal elimination.⁴ Support for this concept has been provided by an ultrastructural study of acquired perforating dermatosis that showed hair shaft fragments within transepidermal channels, even in patients in whom follicular involvement was not demonstrable on routine light microscopy. Factors that may promote coiling of hairs include follicular hyperkeratosis (occasional perforated follicles can be identified in keratosis pilaris) or contact dermatitis (eg, resulting from formaldehyde in clothing). Finally, trauma, such as scratching of pruritic skin, may well play a significant role in lesional development, possibly by setting in motion one or more of the pathologic events described above.⁵

Frequency

United States

Incidence of perforating folliculitis in the United States is not known precisely, although the disorder is not uncommon. In Detroit, Michigan, 50 cases were reported during a 2-year period in the early 1970s, although this observation was followed by a declining incidence of new cases.

International

International incidence of perforating folliculitis is not known.

Mortality/Morbidity

Perforating folliculitis Morbidity is associated with the cosmetic appearance of lesions and the pruritus that occasionally accompanies them. Although cutaneous disease is insignificant, substantial morbidity or mortality rates can be seen in association with the primary underlying diseases, such as diabetes mellitus or chronic renal failure.

Race

Although generally no ethnic predilection has been identified, 1 study found a higher incidence of Kyrle disease in chronic renal failure among African American individuals.

Sex

Perforating folliculitis occurs equally in males and females; no sex predilection has been reported.

Age

Perforating folliculitis is more common in the second through fourth decades of life.

Clinical

History

In perforating folliculitis, papules typically are concentrated on hair-bearing portions of the extremities (arms, thighs) and buttocks. Often, lesions are asymptomatic, although pruritus may be a striking feature, especially in patients with renal insufficiency. Lesions may wax and wane and persist for months or years. Spontaneous remission can occur, and remission following renal transplantation has been documented in 1 patient who developed lesions secondary to renal failure.

Physical

Typical primary lesions of perforating folliculitis consist of 2-8 mm diameter scaly folliculocentric papules with small central keratotic plugs and varying degrees of erythema (see Media File 1).

Compression of papules may yield keratin debris and a coiled hair or hair fragments. An initial eruption of follicular pustules, followed by typical plugged papules and subsequent development of prurigo-nodularis–like lesions was reported in 1 study. The Köebner phenomenon usually is not readily demonstrable, but a linear configuration occasionally can be observed. A case of progressive generalized perforating folliculitis has been reported to be associated with erythroderma, keratoderma of the palms and soles, alopecia of the scalp and eyebrows, and nail changes. Accompanying jaundice has been observed in patients with underlying liver disease.⁶

Causes

A number of reported cases of perforating folliculitis appear to be idiopathic, but specific associations also have been observed. Although some associations could be coincidental, the association with chronic renal failure (including both dialysis-dependent and nondialysis patients) is relatively common, suggesting a pathogenetic link.^{7,8,9,10,11,12} Perforating folliculitis also is observed relatively commonly in association with diabetes mellitus.

Less common associations include sclerosing cholangitis,^13,14 hypertension, atherosclerotic cardiovascular disease, acanthosis nigricans, psoriasis,¹⁵ and phrynoderma.¹⁶ A single case report described an association with Poland syndrome (unilateral absence of the pectoralis major muscle and ipsilateral symbrachydactyly), but this patient also had diabetes mellitus, hyperuricemia, and dilated cardiomyopathy.¹⁷ A single case highlighted the presence of perforating folliculitis in a patient with human immunodeficiency virus infection.¹⁸ Drug-induced cases include associations with infliximab and etanercept as possible inciting agents in a patient with rheumatoid arthritis¹⁹ and dose-dependent association of sorafenib with skin lesions of perforating folliculitis.²⁰

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