Sir,

Folliculitis decalvans (FD) is a rare form of primary neutrophilic cicatricial alopecia. It is a highly distressing disease that affects young and middle-aged adults, with a slight male predominance. Its pathogenesis remains unclear [1]. Herein, we report the case of a patient who presented with FD occurring on an alopecic plaque complicating a forceps-assisted delivery.

A fourteen-year-old patient referred from pediatrics presented with painful and pruritic lesions that had been evolving for two months on a partially depilated area of the scalp from the neonatal period, complicating a vacuum-assisted delivery.

A dermatological examination revealed a rounded alopecic patch on the vertex, about 12 cm wide, with smooth skin, in some places, with sparse hair in clumps, and in other, with erosions topped by hemorrhagic and melic crusts; the rest of the hair was normal (Fig. 1a). Trichoscopy showed the absence of pilar orifices and, in some places, tufted hair, scales, pustules, hemorrhagic, and melic crusts (Fig. 1b). The skin histology was in favor of folliculitis decalvans (Figs. 2a and 2b), and the diagnosis of localized scarring alopecia grafted with a DF was retained. Treatment with tetracycline improved the outbreak.

	Figure 1: (a) Rounded alopecic patch on the vertex, about 12 cm wide, with smooth skin, in some places, with sparse hair in tufts, in other, with erosions covered by hemorrhagic and melic crusts. (b) Diffuse erythema and polytrichia, scaling, pustules, hemorrhagic, and perifollicular crusts.
	Figure 2: (a) Inflammatory infiltrate in the perifollicular area (HES, 100x). (b) Discrete fibrosis surrounding the ruptured follicle (HES, 100x).

Folliculitis decalvans is a rare chronic and recurrent inflammatory scarring alopecia of the scalp, occurring in young and middle-aged adults. [2] To our knowledge, its occurrence in the pediatric population has not yet been reported. It is characterized by the appearance of a centrifugal alopecic patch that spreads slowly, mainly on the vertex and occipital areas of the scalp, and is associated with follicular pustules, crusts, and tufted hairs [3,4]. Patients frequently complain of itching, trichodynia, or burning sensations [1,3]. The pathogenesis of the disease remains incompletely understood, yet Staphylococcus aureus and other follicular bacteria may often be isolated from pustules, suggesting that bacteria play a role in its etiology [3]. Family case reports and the occurrence of DF in patients with immune dysfunction suggest that defects in the host immune response may also be implicated. Structural abnormalities of the hair follicle and local inflammation that may lead to follicle occlusion and retention of telogen hair have been suggested as mechanical factors contributing to increased follicular clumping [4,5]. Indeed, in our patient, the occurrence of DF on the post-forceps alopecic plaque supported the hypothesis that mechanical factors are involved in the pathogenesis of the disease.

REFERENCES

1.  Porras-Villamil JF, Hinestroza-Ruiz AC, López-Moreno GA, Parra-Sepúlveda DJ. Folliculitis decalvans:A case report of satisfactory recovery after implementing. Case Reports. 2022;8:9-23.

2.  Sillani C, Bin Z, Ying Z, Zeming C, Jian Y, Xingqi Z. Effective treatment of folliculitis decalvans using selected antimicrobial agents. Int J Trichology. 2010;21:20-3.

3.  Pimenta R, Borges-Costa J. Successful treatment with fusidic acid in a patient with folliculitis decalvans. Acta Dermatovenerol Croat. 2019;271:49-50.

4.  Vañó-Galván S, Molina-Ruiz AM, Fernández-Crehuet P, Rodrigues-Barata AR, Arias-Santiago S, Serrano-Falcón C, et al. Folliculitis decalvans:A multicentre review of 82 patients. J Eur Acad Dermatol Venereol. 2015;299:1750-7.

5.  Douwes KE, Landthaler M, Szeimies RM. Simultaneous occurrence of folliculitis decalvans capillitii in identical twins. Br J Dermatol. 2000;1431:195-7.