Exploring the Dermoscopic Patterns in Tuberous Sclerosis

Dear Editor, Tuberous sclerosis complex (TS) is a rare, multi-system, autosomal dominant syndrome caused by mutation in TSC1 and TSC2 genes. It is characterised by tumourigenesis in various organs and distinct cutaneous clinical features which aid in diagnosis.[1] The dermoscopy of these cutaneous features helps in differentiating them from their close clinical differential diagnosis, which may aid in confirming the diagnosis of TS in case of subtle indistinguishable cutaneous features. We examined five patients of TS clinically and through a dermatoscope [Figures 1 and 2]. The following dermoscopic features of lesions under polarised dermoscopy (DermLite DL 200 Hybrid), as clinically diagnosed along with their close differential diagnosis, are described in Table 1 below.Figure 1: (a) Yellow dots present over reddish to brownish background (red arrow), unfocussed and focussed vessels (green arrow). (b) Sharply demarcated areas of a normal pigmented network (red arrow) over depigmented background (blue arrow), retained pigmented network present around hair follicle (red circle) and eccrine gland (green circle). (c) yellowish-brown-coloured structureless area with an accentuated pigmented network (red arrow)Figure 2: (a) Finger-like projection with focussed and unfocussed polymorphic vessels (yellow arrow) with a dull red background (green arrow), homogeneous grey area on the tip of lesion (blue arrow). (b) Capillary loop with a distal broad end and proximal tapering end with a whitish halo (yellow arrow), linear black line with uniform thickness suggestive of splinter haemorrhage (orange arrow). Magnification value (x10)Table 1: Dermoscopic findings of tuberous sclerosis along with their differential diagnosisAlthough tuberous sclerosis does not have pathognomonic symptoms, there exists a number of clinical signs among which the cutaneous ones are a component of both major and minor criteria. These cutaneous findings may sometimes not be evident to naked eye. Dermoscopy helps in differentiating the cutaneous features of TS from its close clinical differential diagnosis. Facial angiofibromas can be differentiated from trichoepitheliomas, trichofolliculomas, trichilemmomas, dermal melanocytic nevi, and so on.[1] Similarly, nevus depigmentosus can be differentiated from ash leaf macule. Besides the already described features of ash leaf macule, we observed retention of pigmentary network around appendages, including both hair follicles and eccrine openings. The presence of red comet in nail is a specific feature of TS. Although not present in criteria for diagnosis of TS, it may be a soft pointer towards tuberous sclerosis in the absence of other specific features. Hence, dermoscopy may aid in early diagnosis of TS in the absence of other systemic features or subtle cutaneous findings. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.