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.
Etiology
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.
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.
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Small, dark, follicular papules on the nose.
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Biopsy specimen demonstrates a dilated follicle that contains numerous vellus hairs and keratin debris.
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Potassium hydroxide mount of an extracted plug reveals multiple vellus hairs embedded in keratinous material.
