E-Mail karger@karger.com Case and Review Dermatology 2015;231:195–200 DOI: 10.1159/000381705 Annular Lichenoid Dermatitis of Youth: Report of Six New Cases with Review of the Literature Marco Di Mercurio a Paolo Gisondi a Chiara Colato b Donatella Schena a Giampiero Girolomoni a a Section of Dermatology and Venereology, Department of Medicine, and b Section of Pathology, Department of Pathology and Diagnostics, University of Verona, Verona, Italy Introduction Annular lichenoid dermatitis of youth (ALDY) was firstly described in 2003 in young Mediterranean individuals present- ing with sharply demarcated annular ery- thematous macules and patches with cen- tral hypopigmentation [1]. The lesions typically occur on the groin, flanks and sometimes the axillae. The clinical features may suggest inflammatory morphea, my- cosis fungoides, vitiligo or annular erythe- ma, whereas histologically the main differ- ential diagnosis includes other lichenoid dermatoses and mycosis fungoides. The histological hallmark of ALDY is an inter- face dermatitis affecting specifically the tips of the rete ridges, with massive apo- ptosis of keratinocytes limited to this area and thus configuring a squared base. Since the initial description, other cases have been reported. In this study we describe the clinical and histological features of six new patients with ALDY and review all cases published after the initial description [2–11]. Patients The characteristics of the six patients diagnosed at our institution from 2010 to 2014 are reported in table 1. They were all Key Words Annular lichenoid dermatitis of youth · Interface dermatitis · Lichenoid dermatitis · Mycosis fungoides Abstract Background: Annular lichenoid dermatitis of youth (ALDY) is an uncommon disease clinically reminiscent of morphea, annular erythema or mycosis fungoides. Objective: To describe the histological and clinical fea- tures of a small series of patients with ALDY and to review the literature. Patients: We de- scribe the clinical and histological features of six patients (age range 7–79 years) with asymptomatic erythematous macules and patches with a red-brownish border and cen- tral hypopigmentation, mostly distributed on the groin and flanks. Histologically, all cases showed lichenoid dermatitis limited to the tips of rete ridges, with many intraepider- mal CD8+ and some CD4+ T cells. T cell re- ceptor rearrangement was absent in all cas- es. A total of 44 patients with a consistent clinical and histological picture have been described. The disease is sensitive to topi- cal and/or systemic corticosteroids. Conclu- sions: ALDY is a unique lichenoid dermatitis for whose diagnosis a clinical-pathological correlation is essential. The disease typically affects young patients, more rarely adults and elderly. © 2015 S. Karger AG, Basel Received: November 19, 2014 Accepted after revision: March 16, 2015 Published online: July 9, 2015 Dr. Paolo Gisondi Section of Dermatology and Venereology Department of Medicine, University of Verona Piazzale A. Stefani 1, IT–37126 Verona (Italy) E-Mail paolo.gisondi  @  univr.it © 2015 S. Karger AG, Basel 1018–8665/15/2313–0195$39.50/0 www.karger.com/drm males, age ranging from 7 to 79 years. Le- sions consisted of asymptomatic round- ed, oval or annular red-brown macules or patches, developed from initial erythema- tous macules with peripheral spreading. Most lesions showed the characteristic an- nular or archway shape, with a raised ery- thematous border and a hypopigmented center. Two patients had five (case 1) and four lesions (case 2), respectively, the oldest patient (case 3) had three lesions, whereas three patients had only one lesion (cases 4, 5 and 6). The lesions were located on the side of the trunk, the groin and/or the axil- lary regions (fig. 1). The duration of the le- sions ranged between 2 and 48 months. The main differential diagnosis included eczema, erythema annulare centrifugum, morphea and mycosis fungoides. The pa- tients were otherwise healthy. Methods In all six cases, 5-mm punch biopsies were taken from the periphery of the le- sions and routinely processed and stained with hematoxylin and eosin; periodic acid- Schiff staining was also performed. Immu- nohistochemical staining was performed with the Leica Microsystems Bond-Max poly HRP Autostainer System. The prima- ry antibodies used were: CD1a (Dako 010