Ultrastructural Study of Acquired Pili Torti‐like Hair Defects Accompanying Pseudopelade

Abstract

Acquired structural hair defects are caused by various physical and chemical manipulations. Plucked hairs and hair follicle biopsy specimens of pili torti-like hairs that arose from pseudopelade scalp were studied. In scanning electron microscopy, the hair shafts had a segmental pili torti-like appearance, accompanied by oblique or longitudinal grooves and ridges. In light microscopy, the hair follicles showed an asymmetric hair bulb and inner root sheath, and a shortened keratogenous zone within sclerosing fibrous connective tissue. In transmission electron microscopy, the numbers and thickness of the hair cuticle cells were different on the opposite sides of the hair shaft. The hair cuticle was irregularly shaped and formed asymmetric waves. The tonofilaments in the hair cortex ran almost parallel to the hair axis. From these findings, it was clear that the grooves and ridges were produced by the deformed hair cuticle and cortex, whose shapes were modulated by the asymmetric inner root sheath. This asymmetry most likely resulted from a dysfunctional dermal papilla, which was affected by fibrosis. The pili torti-like appearance appeared to be caused by the grooves and ridges that ran obliquely on the hair shaft surface.

Update on primary cicatricial alopecias

“…Within large areas of cicatrized alopecia, isolated and grouped hairs may appear kinked. 172,174,193 Active disease is marked by a positive pull test result for anagen hairs. 172,174 There have been 2 reports of beard involvement with pseudopelade of Brocq.…”

Cutaneous T-cell lymphoma in erythrodermic cases may be suspected on the basis of scalp examination with dermoscopy

“…The most common congenital defects and syndromes associated with pili torti include: Ronchese syndrome, Beare syndrome, Bjornstad syndrome, Menkes syndrome, Rapp-Hodgkin syndrome, trichodysplasia-xeroderma, trichothiodystrophy among other rarer inherited diseases and syndromes [18][19][20] . Acquired forms of pili torti may result from repetitive trauma, oral retinoid treatment, anorexia, inflammation in cicatricial alopecia, graft-vs-host disease, scleroderma and after hair transplantation 21,22 . In acquired pili torti, it is presumed that uneven perifollicular fibrosis causes rotational forces on the inner root sheath that distort the hair follicle inducing formation of pili torti that may easily break, leaving broken hairs or black dots 17 .…”

Pseudopelade of Brocq

“…The hair shafts at the edge of an active alopecic patch are easily extractable and may be twisted (34). Typical of many forms of primary scarring alopecia, scattered isolated and grouped hairs may remain in the patches of alopecia and may appear curly due to follicular distortion (12,17,42) (FIG. 4).…”