Trichostasis Spinulosa Presenting as Itchy Papules in a Young Lady

Abstract

Sir, A 27-year-old woman of South Asian descent presented with gradually erupting itchy papules and open pores behind her left ear for the past 1 month. Her past medical or family history was unremarkable. Physical examination revealed multiple dark brown keratotic cystic plaques and comedones behind her left ear. A skin biopsy was taken from the representative area and sent for histopathological examination. Light microscopy revealed three cystically dilated hair follicles with retention of small hair shafts and keratinous material within the dermis. Perifollicular mononuclear cell infiltration was evident [Figures 1 and 2]. Based on the above features, a diagnosis of Trichostasis Spinulosa (TS) was offered. The patient was started on 0.05% tretinoin cream to be applied over the affected area daily at bedtime, and was also given oral antihistaminics to relieve the itching. A marked improvement of the lesions was seen at the 3-month follow-up. Figure 1 Photomicrograph revealing three cystically dilated hair follicles within the dermis (H and E, ×100) Figure 2 Dilated hair follicle with retention of small hair shafts and keratinous material. Perifollicular chronic inflammatory infiltrate is also evident (H and E, ×400) TS is a relatively common but underdiagnosed disorder of the pilosebaceous follicles, in which there is follicular hyperkeratosis of a dilated vellus hair follicle with retention of successive telogen hairs arranged in parallel among the keratinaceous material.[1] It presents as raised follicular spicules or as open comedones on the face, nose or cheeks of middle-aged and older individuals, and may be pruritic.[2] The etiology of TS is not known for certain. Congenital dysplasia of the hair follicles as well as external factors such as dust, oils, ultraviolet light, heat and irritants have been proposed. According to one of the hypotheses, hair shaft entrapment is the result of hyperkeratosis in the follicular infundibulum thus producing an obstruction to the normal hair shedding.[3] Topical treatments offer temporary relief, but permanent removal of the abnormal follicles using hair removal lasers may result in a definite cure.[4]