Background
In trichostasis spinulosa (TS), clusters of vellus hairs become embedded within hair follicles, with resultant dark, spiny papules on the face or trunk. Trichostasis spinulosa frequently is discovered as an incidental finding, and often it is confused with keratosis pilaris or acne comedones.
Pathophysiology
Trichostasis spinulosa results from successive production and retention of vellus telogen club hairs from a single hair matrix in a follicle. Hyperkeratosis plugs the follicle and results in the retention of the vellus hairs in the obstructed follicular infundibulum. The precise cause of this phenomenon remains undetermined.
Epidemiology
Frequency
To the authors' knowledge, studies of prevalence have not been undertaken, but published reports indicate that the condition is common, especially in elderly persons.
Sex
Most reports state that trichostasis spinulosa more frequently affects male patients, but it may occur equally in men and women.
Age
Rarely, cases are reported in children, but the condition nearly always occurs in adults, especially older adults.
Prognosis
Trichostasis spinulosa (TS) persists and remains medically inconsequential; however, the condition may become more severe with age. Trichostasis spinulosa is primarily a cosmetic concern. Trichostasis spinulosa does not cause morbidity.
History
In most cases, the condition does not lead to any subjective complaint and is observed only as an incidental finding. Pruritus is occasionally present, as is roughness of the skin. Pruritus may be more common when lesions are present on the trunk and arms of young adults. In younger patients, the chief complaint may be a cosmetic concern about facial lesions, which are frequently confused with open comedones. In this setting, patients may report a history of unsuccessful treatment for acne.
Physical Examination
Pertinent physical findings of trichostasis spinulosa are limited to the skin. Because spinous plugs may be inapparent to the naked eye, examination of suspected lesions under a hand lens or with a dermatoscope is recommended.
Lesions typically appear as dark, follicular plugs or papules. The lesions may have protruding tufts or spines of fine hair that can easily be removed with a comedo extractor or small-toothed forceps without discomfort to the patient. The horny plugs are soft and contain 5-25 hairs per plug. Scales may sometimes be present. Note the image below.
View Image | Small, dark, follicular papules on the nose. |
Lesions may occur anywhere on the body, but they characteristically appear on the face, especially the nose, and the upper part of the trunk and arms, especially the interscapular area. Lesions less typically appear on other areas of the head, neck, and cheeks.
Lesions are characteristically less than or equal to 1 mm.
Lesions characteristically are black.
Causes
The cause is unknown.
Various explanations for the hyperkeratosis and plugging of the follicular apparatus are proposed. Internal mechanisms, such as endocrine or metabolic disturbances, are suggested. Widespread trichostasis spinulosus has been reported with renal failure.[1] External mechanisms include the use of irritating soaps or paraffin-containing creams and prolonged exposure to dust, hydrocarbons, or industrial oils. Trichostasis spinulosa has also been associated with prolonged use of clobetasol.[2]
Some consider trichostasis spinulosa to be a variant of the comedonal lesions of acne; they note the similar distribution of lesions and the rarity of trichostasis spinulosa among preadolescent patients.
Microorganisms are also suggested to have a causative role. Propionibacterium acnes and Pityrosporum species are implicated as possible organisms.
Approach Considerations
The diagnosis of trichostasis spinulosa (TS) can be made clinically without obtaining a biopsy specimen. If the diagnosis is in doubt, a specimen may easily be obtained by removing a hair plug with a forceps or comedone extractor. The specimen may be placed on a glass slide for microscopic examination. Treatment with potassium hydroxide dissolves the keratinous plug, leaving numerous vellus hairs in a characteristic tuft. Dermatoscopy may also be used to help confirm the diagnosis.[4]
Histologic Findings
If a biopsy specimen is obtained, histology reveals a dilated hair follicle housing multiple vellus hairs in a keratotic sheath and acanthosis of the follicular epithelium (see the images below). Inflammatory changes are not a characteristic of trichostasis spinulosa.
View Image | Biopsy specimen demonstrates a dilated follicle that contains numerous vellus hairs and keratin debris. |
View Image | Potassium hydroxide mount of an extracted plug reveals multiple vellus hairs embedded in keratinous material. |
Medical Care
Treatment for trichostasis spinulosa (TS) is usually administered for cosmetic purposes. The individual plugs of impacted hairs may be removed by means of the following:
Tweezing with forceps
Pressure expression with a comedone extractor
Use of depilatory wax, adhesive strips,[5] or laser depilation[6]
Emollients and keratolytics may also be helpful. After the apparent lesions are removed, topical retinoic acids can be used to help prevent future lesions.
Surgical Care
Laser treatment with a 755-nm long-pulsed alexandrite laser may also be considered.[7, 8]
Prevention
After the apparent lesions are removed, topical retinoic acids can be used to help prevent future lesions; however, recurrence of lesions is commonplace.
Medication Summary
Varying degrees of success are reported with the use of topical tretinoin, which is used primarily as a preventive measure.
Tretinoin topical (Avita, Retin-A, Tretin-X, Atralin, Avita)
Clinical Context:
Tretinoin inhibits microcomedo formation and eliminates the lesions present. It makes keratinocytes in sebaceous follicles less adherent and easier to remove. Use 0.05% cream.
Class Summary
Retinoid-like agents decrease the cohesiveness of abnormal hyperproliferative keratinocytes and may reduce the potential for malignant degeneration. These drugs modulate keratinocyte differentiation and reduce the risk of skin cancer formation in patients with renal transplants. Applied topically, retinoids may prevent the development of lesions.
Author
Nicholas V Nguyen, MD, Director of Pediatric Dermatology, Akron Children's Hospital
Disclosure: Nothing to disclose.
Coauthor(s)
Tracy Funk, MD, Fellow in Pediatric Dermatology, Department of Dermatology, The Children’s Hospital Colorado
Disclosure: Nothing to disclose.
Specialty Editors
Michael J Wells, MD, FAAD, Dermatologic/Mohs Surgeon, The Surgery Center at Plano Dermatology
Disclosure: Nothing to disclose.
Jaggi Rao, MD, FRCPC, Clinical Professor of Medicine, Division of Dermatology and Cutaneous Sciences, Director of Dermatology Residency Program, University of Alberta Faculty of Medicine and Dentistry, Canada
Disclosure: Nothing to disclose.
Chief Editor
Dirk M Elston, MD, Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
Leonard Sperling, MD, Chair, Professor, Department of Dermatology, Uniformed Services University of the Health Sciences
Disclosure: Nothing to disclose.
Acknowledgements
Stephen J Krivda, MD Assistant Professor of Dermatology, Uniformed Services University of the Health Sciences; Chief of the Integrated Department of Dermatology, Chief of Dermatology Service, Director of Dermatopathology, Staff Dermatopathologist, Walter Reed Army Medical Center; Head, Department of Dermatology, Staff Dermatologist and Dermatopathologist, National Naval Medical Center
Stephen J Krivda, MD is a member of the following medical societies: American Academy of Dermatology, American Society of Dermatopathology, Association of Military Dermatologists, and Phi Beta Kappa
Disclosure: Nothing to disclose.
George E vonHilsheimer, MD Assistant Professor of Dermatology, Uniformed Services University of the Health Sciences; Chief, Staff Dermatologist, Department of Medicine, Martin Army Community Hospital, Fort Benning, Georgia
George E vonHilsheimer, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, and Association of Military Dermatologists
Disclosure: Nothing to disclose.
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