LAUSR

To the Editor: Secondary syphilis may manifest as syphilitic alopecia (SA), a nonscarring alopecia with a prevalence ranging from 3% to 22%. Examination of the hair using a dermatoscope, a noninvasive bedside test known as trichoscopy, may help differentiate SA from other forms of hair loss. 3 This systematic review followed Preferred Reporting Items for Systematic Reviews and MetaAnalyses guidelines to summarise published data on trichoscopic findings of SA (PROSPERO CRD42018092159). Details of the searches (from inception to 22 April 2021), study selection, data extraction and quality assessment are provided in online supplemental figure 1 and online supplemental tables 1 and 2. Across 16 studies, 23 patients (96% male, mean age 34 years) were reported (table 1). The average time to presentation was 2 months. Motheaten and diffuse patterns of alopecia were seen in 78% and 22% of patients respectively; no studies reported a mixed pattern of alopecia. Essential SA (alopecia as an isolated presentation of syphilis) was reported in 35% of patients. Patients presented with nonspecific trichoscopic findings of decreased hairs per follicular unit (n=17, 74%), vellus hairs (n=17, 74%), background erythema (n=14, 61%), focal atrichia (n=12, 52%) and yellow dots (n=11, 48%) (figure 1). Less frequently, patients were noted to have black dots (n=9, 39%), broken hairs (n=8, 35%), zigzag hairs (n=3, 13%) and follicular hyperkeratosis or plugging (n=3, 13%). Diffuse white scale, depigmented capillaries, brown perifollicular rings and pigtail hairs were also reported. These findings are consistent with current literature which is yet to identify pathognomonic features for SA. There are, however, important distinctions to be made between the trichoscopic findings of SA and its main differential diagnoses: alopecia areata, trichotillomania and tinea capitis (table 2). Diagnosis of syphilis was usually made by a combination of nontreponemal tests and treponemal tests. Two studies (13%) did not report satisfactory serological confirmation of syphilis, defined as confirmation via two treponemal tests Research Letter