An atypical case of trichofolliculoma: a contribution of the dermoscope

Dear editor, Trichofolliculoma is a rare benign adnexal tumor, also described as a hamartoma with pilar differentiation [1]. It often manifests in adulthood as a solitary papule or nodule centered on a tuft of fluffy white hair mainly affecting the cephalic region. Its dermoscopic appearance is not widely reported. In addition to the signs that will be reported in our case, the following aspects were described: yellow areas, horny plugs, white downy hairs, described as ‘troll hair’ sign [2], which are so characteristic of trichofolliculoma although they can be missing in atypical forms. Histology allows a definitive diagnosis by showing a characteristic appearance of a tumor consisting of a dilated central follicle corresponding to the primary follicle, lined with a thick wall into which secondary follicles present a very variable differentiation [3]. Sometimes it may have rudimentary sebaceous structures on the seborrheic areas. Excision is the rule without margins given the benignity of the tumor although cases of perineural invasion and recurrence after excision have been described [4,5]. A 56-year-old female patient, with no particular history, consulted for an asymptomatic raised lesion of the scalp that had been present for 15 years. The clinical examination revealed a painless flesh-colored nodule measuring 1.5 cm in large diameter with a firm consistency hollowed out by two peripheral holes from which a tuft of hair emerges (Fig. 1).Figure 1: Clinical aspect of the scalp nodule with black hair growth.Dermoscope examination showed fine telangiectasias with a tuft of downy, black hair surrounded by yellowish scales (Fig. 2). The following diagnoses were mentioned: a trichofolliculoma and an achromic dermal nevus. An excisional biopsy was performed revealing on histological examination a dilated hair follicle comprising keratin and hair shaft debris to which several branched follicles presented at various degrees of maturation were connected. The whole thing is surrounded by collagen fibrosis.Figure 2: Dermoscope examination showed fine telangiectasias with a tuft of downy, black hair surrounded by yellowish scales.In light of this histological aspect, the diagnosis of a trichofolliculoma was retained and no recurrence was observed after 6 months of follow-up. Acknowledgments Declaration of patient consent: The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient understands that names and initials will not be published and due efforts will be made to conceal patient identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.