CPD • A memorable patient CED Clinical and Experimental Dermatology CPD A large shagreen patch with overlying verrucous epidermal naevus: a curious case of colocalization A. Bishnoi, 1 D.De, 1 K. Vinay, 1 V. Vishwajeet 2 and U. N. Saikia 2 Departments of 1 Dermatology and 2 Histopathology, Postgraduate Institute of Medical Education and Research, Sector 12, Chandigarh, India doi: 10.1111/ced.13681 Collagenomas measuring > 10 mm are known as sha- green patches, and are commonly observed in tuber- ous sclerosis complex (TSC). 1 Development of epidermal changes overlying a collagenoma is quite rare. We present a unique case of TSC showing col- ocalization of a large shagreen patch and a verrucous epidermal naevus (VEN). An adolescent girl presented with a progressive growth over her lower back that had been present since early childhood. Her parents were concerned about the central hyperpigmentation that had devel- oped over the past 4 years. The patient had previously been diagnosed with sporadic TSC and was receiving valproic acid for associated seizures. Physical examination revealed a large, irregular, firm, skin-coloured, nontender plaque with prominent follicu- lar orifices on her lower back. Numerous smaller lesions of similar morphology were clustered in a corymbose pattern surrounding the larger plaque. Interestingly, there was also a well-defined, circumscribed, hyper- pigmented plaque with firm, verrucous excrescences imparting a pebbly surface in the centre of the larger plaque (Fig. 1), which was clearly demarcated from the surrounding plaque and showed tethering on its medial aspect. There was no overlying hypertrichosis. Other phenotypic features of TSC observed were multiple facial angiofibromas, fibrous forehead plaque and ash-leaf macules. There was no evidence of any pulmonary, car- diac or renal involvement. The diagnosis of TSC was reaffirmed based on the classic clinical presentation. Histological examination of a punch biopsy taken from the central pigmented lesion showed an acan- thotic epidermis with papillomatosis and overlying hyperkeratosis in a church-spire pattern. The basal layer was hyperpigmented. The dermis showed dif- fusely thickened and clustered collagen bundles, which stained greenish-blue with Masson trichrome (Fig. 2). The histology was representative of a nonepidermolytic VEN overlying a collagenoma. T1 -and T2-weighted magnetic resonance imaging of the lesion revealed a central hypointense lesion sur- rounded by an outer hyperintense lesion, with no extension to the underlying neuraxis. Correspondence: Dr Keshavamurthy Vinay, Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh 160012, India E-mail: keshavmurthy@gmail.com Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 8 February 2018 Figure 1 A case of tuberous sclerosis complex showing a circum- scribed, hyperpigmented pebbly plaque with firm, verrucous excrescences suggestive of verrucous epidermal naevus in the centre of a larger, oval to irregular, skin-coloured, firm, non- tender plaque with prominent follicular orifices suggestive of shagreen patch. Numerous secondary lesions are seen surrounding the central large plaque in a corymbose pattern. ª 2018 British Association of Dermatologists Clinical and Experimental Dermatology 1 CPD