Trichostasis Spinulosa

Updated: Nov 08, 2021
Author: Nicholas V Nguyen, MD; Chief Editor: Dirk M Elston, MD 



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.


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.


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] One report describes trichostasis spinulosa as a manifestation of cutaneous graft versus host disease in a patient who underwent hematopoietic stem cell transplantation.[2]  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.[3]

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.



To the authors' knowledge, studies of prevalence have not been undertaken, but published reports indicate that the condition is common, especially in elderly persons.


Most reports state that trichostasis spinulosa more frequently affects male patients, but it may occur equally in men and women.


Rarely, cases are reported in children, but the condition nearly always occurs in adults, especially older adults.


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.




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.[4]

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.

Small, dark, follicular papules on the nose. 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. One report describes trichostasis spinulosa on the back.[4]

Lesions are characteristically less than or equal to 1 mm.

Lesions characteristically are black.



Diagnostic Considerations

Also consider acne comedones.[5]

Differential Diagnoses



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.[6]

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.

Biopsy specimen demonstrates a dilated follicle th Biopsy specimen demonstrates a dilated follicle that contains numerous vellus hairs and keratin debris.
Potassium hydroxide mount of an extracted plug rev 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,[7] or laser depilation[8]

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.[9, 10]


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.

Retinoid-like Agents

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.

Tretinoin topical (Avita, Retin-A, Tretin-X, Atralin, Avita)

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.