Dermatology: Practical and Conceptual Observation | Dermatol Pract Concept 2016;6(2):10 53 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com Introduction In approximately 10% of cases, Darier’s disease (DD) may present in a localized pattern as the result of a postzygotic mosaicism in the ATP2A2 gene (type 1 segmental DD) [1]. Such a variant is characterized by hyperkeratotic reddish- brownish papules having a linear distribution along Blasch- ko’s lines, which frequently get worse during the summer [1]. Since type 1 segmental DD usually lacks diagnostic clues typical of the generalized form, i.e., positive family history of the disease, nail and mucosal abnormalities, and/or acral involvement, its distinction from other acquired inflamma- tory blaschkolinear dermatoses may often be quite challeng- ing, thus requiring histopathological examination to reach a definitive diagnosis [1]. We here describe for the first time the use of dermoscopy in a patient with type 1 segmental DD. Case presentation A 25-year-old Caucasian man presented with a two-year his- tory of slightly itchy skin lesions on the right side of his abdo- men, which were reportedly worse in the summer months. There was no family history of similar problems. Physical examination showed numerous hyperkeratotic reddish- brownish papules in a blaschkoid distribution (Figure 1a). No mucosal or nail lesions were present. On polarized light Dermoscopy: a useful auxiliary tool in the diagnosis of type 1 segmental Darier’s disease Enzo Errichetti1, Vincenzo Maione2, Enrico Pegolo3, Giuseppe Stinco1 1 Department of Experimental and Clinical Medicine, Institute of Dermatology, University of Udine, Italy 2 Department of Dermatology, “Hôpital Saint Louis”, Paris Diderot University, France 3 Department of Medical and Biological Sciences, Institute of Anatomic Pathology, University of Udine, Italy Key words: Darier’s disease, dermoscopy; differential diagnosis; mosaicism, type 1 segmental Darier’s disease Citation: Errichetti E, Maoine V, Pegolo E, Stinco G. Dermoscopy: a useful auxiliary tool in the diagnosis of type 1 segmental Darier’s disease. Dermatol Pract Concept 2016;6(2):10. doi: 10.5826/dpc.0602a10 Received: November 18, 2015; Accepted: March 12, 2016 ; Published: April 30, 2016 Copyright: ©2016 Errichetti et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. All authors have contributed significantly to this publication. Corresponding author: Enzo Errichetti, MD, Institute of Dermatology, “Santa Maria della Misericordia” University Hospital, Piazzale Santa Maria della Misericordia, 15 –33100 Udine, Italy. Tel. (+39) 0432559820. E-mail. enzoerri@yahoo.it Type 1 segmental Darier’s disease is a blaschkolinear variant of Darier’s disease resulting from a postzygotic mosaicism. Since it usually lacks diagnostic clues typical of the generalized form, includ- ing positive family history of the disease, nail and mucosal abnormalities, and/or acral involvement, its distinction from other acquired inflammatory blaschkolinear dermatoses may often be quite chal- lenging, thus requiring histopathological examination to reach a definitive diagnosis. We report a case of type 1 segmental Darier’s disease with its dermoscopic findings in order to show the usefulness of dermoscopy in assisting the noninvasive identification of this condition. ABSTRACT 54 Observation | Dermatol Pract Concept 2016;6(2):10 authors found a variable vascular pattern, including red dots, red lines, or erythema, and constant nonvascular structures, which they named “giant pseudocomedones,” consisting in dilated oval openings with raised or flat bor- ders and central brown or yellowish hyperkeratotic plugs [7]. However, according to our recent study on 11 patients, DD may display a more complex dermoscopic pattern characterized by a centrally located polygonal, star-like or roundish-oval shaped yellowish/brownish area, surrounded by a more or less thin whitish halo, overlying a pinkish homogeneous structureless area, with or without whitish scales and dotted and/or linear vessels presenting a whit- ish halo [8]. Indeed, we observed a similar appearance in the present “localized” instance. In terms of dermoscopic- pathological correlation, the central yellowish-brownish area and its whitish halo would correspond to the compact hyperkeratosis and acanthosis (Figure 1b, c), respectively, while the pinkish background and vessels would be due to the dermal inflammation [8-9]. By reporting the dermoscopy of this case of type 1 seg- mental DD, we would like to point out the usefulness of such dermoscopic examination (carried out with DermLite DL3 x10; 3Gen, San Juan Capistrano, CA, USA), most papules displayed the same aspect, namely, centrally located, round- ish or polygonal, yellowish/brownish areas of various sizes (often with a whitish halo) that were surrounded by a pinkish homogeneous structureless areas (with or without linear and/ or dotted vessels) (Figure 1b). Histology revealed compact hyperkeratosis, parakeratosis, acanthosis, foci of suprabasal acantholysis, dyskeratotic cells in the form of “corp ronds” and “grains,” and superficial dermal chronic inflammation (Figure 1c), thus leading to the diagnosis of type 1 segmental DD. The patient was treated with tretinoin 0.05% cream (once a day) with moderate improvement of the clinical pic- ture after three weeks. Discussion During the last years, the use of dermoscopy in “general” dermatology has considerably increased [2-6]. The first dermoscopic description of DD dates back to 2004, when Vázquez-López et al reported a study on five patients. The Figure 1. Physical examination shows numerous hyperkeratotic reddish-brownish papules in a blaschkoid distribution on the right side of the abdomen; unrelated sparse lesions of folliculitis and the scar at the biopsy site are also evident on the right subaxillary region and costal arch, respectively (a). Polarized light dermoscopic examination (x10 magnification) of two contiguous papules displays centrally located, polygonal (outlined in black) or roundish (outlined in black), yellowish/brownish areas (black arrows) presenting a whitish halo (black stars), which are surrounded by a pinkish homogeneous structureless area with some dotted vessels (black arrowheads) (b). Histology shows com- pact hyperkeratosis (black arrow), parakeratosis, acanthosis (black stars), foci of suprabasal acantholysis, dyskeratotic cells (better visible in the box) in the form of “corp ronds” and “grains”, and superficial dermal chronic inflammation (hematoxylin and eosin stain x100) (c). [Copyright: ©2016 Errichetti et al.] Observation | Dermatol Pract Concept 2016;6(2):10 55 3. Errichetti E, Lacarrubba F, Micali G, Piccirillo A, Stinco G. Differ- entiation of pityriasis lichenoides chronica from guttate psoriasis by dermoscopy. Clin Exp Dermatol 2015; 40(7):804-6. PMID: 25682853. DOI: 10.1111/ced.12580 4. Errichetti E, Stinco G. Dermoscopy of idiopathic guttate hy- pomelanosis. J Dermatol 2015; 42(11):1118-9. PMID: 26212033. DOI: 10.1111/1346-8138.13035 5. Errichetti E, Stinco G. Dermoscopy in differential diagnosis of palmar psoriasis and chronic hand eczema. J Dermatol 2015 Oct 13. [Epub ahead of print] PMID: 26460228. DOI: 10.1111/1346- 8138.13142 6. Errichetti E, Piccirillo A, Stinco G. Dermoscopy of prurigo nodularis. J Dermatol 2015; 42(6):632-4. PMID: 25808786. DOI: 10.1111/1346-8138.12844 7. Vázquez-López F, Lopez-Escobar M, Maldonado-Seral C, Perez- Oliva N, Marghoob AA. The handheld dermoscope improves the recognition of giant pseudocomedones in Darier’s disease. J Am Acad Dermatol 2004; 50(3):454-5. PMID: 14988691. DOI: 10.1016/S0190-9622(03)02475-7 8. Errichetti E, Stinco G, Lacarrubba F, Micali G. Dermoscopy of Darier’s disease. J Eur Acad Dermatol Venereol 2015 Aug 6. [Epub ahead of print] PMID: 26248700. DOI: 10.1111/jdv.13238 9. Lacarrubba F, Verzì AE, Errichetti E, Stinco G, Micali G. Darier disease: Dermoscopy, confocal microscopy, and histologic correla- tions. J Am Acad Dermatol 2015; 73(3):e97-9. PMID: 26282823. DOI: 10.1016/j.jaad.2015.04.066 10. Jackson SM, Nesbitt LT. The Diagnosis. In: Jackson SM, Nesbitt LT, eds. Differential Diagnosis for the Dermatologist, 2nd ed. New York: Springer, 2012; 857-8. a low-cost and noninvasive technique in assisting the recogni- tion of this variant of DD. In fact, even though the definitive diagnosis of such a condition relies on histopathological anal- ysis, dermoscopy may be used as an auxiliary tool to rule out the other major acquired inflammatory papular dermatoses which may present in a blaschkolinear fashion and enter into the differential diagnosis [10], including lichen planus, which is typically characterized by Wickham striae (seen as round, linear, reticular or annular pearly-whitish structures) [2]; psoriasis, showing white scales and symmetrically/regularly distributed dotted vessels on a light or dull red background [2,3] and lichen striatus, displaying vessels of mixed morphol- ogy (dotted and/or linear) over a pinkish background, with or without whitish scales (personal observations). References 1. Sanderson EA, Killoran CE, Pedvis-Leftick A, Wilkel CS. Local- ized Darier’s disease in a Blaschkoid distribution: Two cases of phenotypic mosaicism and a review of mosaic Darier’s dis- ease. J Dermatol 2007; 34(11):761-4. PMID: 17973816. DOI: 10.1111/j.1346-8138.2007.00379.x 2. Errichetti E, Stinco G. The practical usefulness of dermoscopy in general dermatology. G Ital Dermatol Venereol 2015; 150(5):533- 46. PMID: 26086412 http://dx.doi.org/10.1016/S0190-9622(03)02475-7