Lipodystrophia centrifugalis abdominalis infantilis accompanied by idiopathic encephalopathy

keratotic plugs can be observed on 3D volume view (Fig. 1b). The 2D sectional views showed cystic dilated hair follicles with presence of plugs. The hairs present on normal skin are not visible. Follicles are dilated containing a homogenous material. Epidermal thickness was increased and dermal capillaries close to the cavities appeared enlarged (Fig. 2b). The clinical and OCT findings suggested the diagnosis of follicular keratosis of the chin. However, given the rarity of this condition, we performed a punch biopsy to rule out a more severe follicular disease such as mucinosis or mycosis fungoides. Histopathology confirmed the diagnosis of follicular keratosis of the chin (Fig. 2a). A treatment by topical tretinoin 0.05% did not improve the lesions. OCT is a non-invasive, in vivo imaging technique. Low-intensity near-infrared light is directed at the skin surface, and the reflected light is captured and produced into an image that shows the internal detail of the structure. A sample beam delivers light to the skin and collects the light scattered back. This sample light is mixed with light that is reflected directly from a reference beam. If the sample and reference light are coherent, the mixing produces an interference pattern that is converted to an image. The image produced along the depth direction is an A-scan. A cross-sectional image (tomography or B-scan) is produced by assembling A-scans. A volumetric image is constructed from a collection of B-scans. OCT is used increasingly in a variety of cutaneous inflammatory or tumoral conditions. Here we report the interest of OCT in a follicular disorder. Follicular keratosis of the chin is a rarely reported entity. A mechanic etiology is suspected but the cause is not always obvious. It can be mistaken with other follicular diseases especially folliculotropic mycosis fungoides, and follicular mucinosis. Here, OCT revealed a cystic dilatation of hair follicles with keratotic plugs that correlated with histology and facilitated the diagnosis. The OCT images of mycosis fungoides, principal differential diagnosis, had been described once. It shows an hyperreflective, thickened stratum corneum and remarkable hyporeflectives oblong structures in the dermis thought to be lymphomatous infiltrates. Reinforcement to our clinical diagnosis by a skin biopsy could not be avoided given the possibility of more severe diseases which have not yet been described reproducibly by OCT. This case did not respond to treatment with topical tretinoin. A fact which is consistent with the other reported cases. Topical corticosteroids have not been found to be more effective. A successful but only suspensive treatment by topical vitamin D3 ointment was reported in one case. The only way to heal this skin disease seems to be by avoiding pressure and friction on the lesion. In conclusion follicular keratosis of the chin is a benign childhood disease that could be recognized easily using OCT. This observation also suggests that OCT could be helpful in the investigation of other skin diseases involving the hair follicle such as acne or rosacea. S. Nguyen,* C. Chiaverini, N. Cardot-Leccia, C. Queille-Roussel, K. Roussel, J.P. Lacour, P. Bahadoran Department of Dermatology, Archet 2 Hospital, University Hospital of Nice, Department of Dermatopathology, Pasteur Hospital, University Hospital of Nice, Centre de Pharmacologie Clinique Appliqu ee a la Dermatologie, Archet 2 Hospital, University Hospital of Nice, Department of Dermatology, Centre de Recherche Clinique, Archet 2 Hospital, University Hospital of Nice, Nice, France *Correspondence: S. Nguyen. E-mail: sophie.nguyen2@gmail.com