We read with interest a report by Flores-Terry et al.1 published recently in the Actas Dermo-Sifiliográficas journal. The authors reported 2 Spanish female patients with "yellow" facial papules(FP) of frontal fibrosing alopecia(FFA) treated with fixed low dose isotretinoine (i.e. 10mg/day). One patient showed an excellent response beginning 1 month after starting treatment and persisting up to 6 months. The other patient showed improvement in the patient’s facial signs after 1.5 months, with a decrease in both the number and extension of FP. The authors stated " There are no data on FP treatment using topical or oral retinoids". However, this claim is uncertain. We found 3 published papers reported the successful use of low dose isotretinoine in FP in FFA/Lichen plano-pilaris (LPP). One of these reports studied 62 patients with "yellow" FP.

Frontal fibrosing alopecia (FFA) is considered a variant of lichen planopilaris affecting mainly the frontotemporal hairline. Since the first report in 1994, several other clinical features have been associated with the disease, such as facial papules (FP).2 Pirmez et al. reported 3 female patients with a biopsy-confirmed FFA. All patients were started on the dosage of 20mg/day of oral isotretinoin for the first month, which was then titrated to 0.5mg/kg/day for the following 2 months (40mg/day in all 3 patients). At the end of the first month, a remarkable improvement was noted, with a reduction in the number and size of FP. At the end of the third month, FP had completely disappeared or were considered minimal. Isotretinoin was then discontinued and hydroxychloroquine 400mg/day was introduced. Another interesting point is that the choice of therapeutic regimen seems to affect the time-to response with oral isotretinoin. Although it is not possible to exclude any role of concurrent systemic and topical treatments, the temporal relation between the introduction of oral isotretinoin and the disappearance of the lesions is remarkable.3 Of 108 patients with FFA followed by Pedrosa et al., 62 patients exhibited yellow facial papules. Yellow papules were found on the temporal area, cheeks, chin, or diffusely distributed throughout the face. Histopathologic findings were invariably similar, with hypertrophic sebaceous glands in the papillary dermis with no associated vellus hair follicle or lichenoid inflammation. This observation led to a hypothesize that inflammation eventually resulted in the loss of vellus hair follicles replaced by fibrous scar tissue, whereas the hypertrophic sebaceous glands still remained, giving the clinical appearance of yellow noninflammatory papules on the face devoid of terminal hairs. In all of these patients, the skin was clinically very soft and thin, which made the hypertrophic sebaceous glands shine through or popping up. This finding may have an impact on therapy, because low-dose isotretinoin resulting in sebaceous gland shrinkage could be a valuable option to improve cosmetic appearance in these cases.4 Those patients were treated with oral low-dose isotretinoin (10mg every other day) for ≥12 months, which yielded a visible reduction of the yellow facial papules and was associated with a reduction of skin roughness after a median of 2 months.4,5 Patients treated with 10mg of isotretinoin every other day reported improvement of skin roughness only after a median of 2 months that was clinically observed after a median of 4 months.5 Yellow facial papules present a distinct histologic pattern, which might represent an intermediate step between an initial perifollicular lichenoid inflammation and the ultimate epidermal atrophy without hair follicles but with large sebaceous glands remaining.5 Hence, there is a difference between the simple FP and the yellow FP; yellow facial papules involve large sebaceous glands lacking vellus hair follicles and lichenoid inflammation.5 In a similar vein, Namazi et al.6 reported 4 cases of famililal LPP presented with isolated "simple" FP. Vellus hair involvement by LPP presenting as facial papules is an uncommon manifestation of LPP, this feature was seen in three of four of their patients. Interestingly, three of the four patients responded well to isotretinoin. One of the 3 responders was on low dose isotretinoin (20mg/day) combined with finasteride (5mg/day).

To sum up, FP has 2 clinical and histopathoogical variants; simple and yellow FP. Both are low-dose isotretinoine responders. The report by Flores-Terry et al.1 represented a cumulative 2 cases with "yellow" FP of FFA responding to a very low dose of isotretinoine.

DECLARATION AUTORIA

Michelangelo Vestita: (1) la concepción y el diseño del estudio, o la adquisición de datos, o el análisis y la interpretación de los datos, (2) el borrador del artículo o la revisión crítica del contenido intelectual, (3) la aprobación definitiva de la versión que se presenta.

Ayman Abdelmaksoud: (1) la concepción y el diseño del estudio, o la adquisición de datos, o el análisis y la interpretación de los datos, (2) el borrador del artículo o la revisión crítica del contenido intelectual, (3) la aprobación definitiva de la versión que se presenta.