Annular lichenoid dermatosis of youth

Annular Lichenoid Dermatitis (of Youth)

About 20 years after its first description, Annular Lichenoid Dermatitis of Youth (ALDY) is recognized as a distinctive lichenoid dermatosis with specific clinical and histological features. The disease occurs mostly in young persons all over the world, runs a chronic course, and has an obscure etiopathogenesis. Clinically, lesions consist of persistent, asymptomatic erythematous macules and round-oval annular patches with a red-violaceous non-scaling border and central hypopigmentation, mostly localized on the groin and flanks. Histology shows a peculiar lichenoid dermatitis characterized by irregular epidermal hyperplasia with an alternation of thinned and quadrangular rete ridges and a dense band-like lichenoid infiltrate of lymphocytes in the papillary dermis. Typically, there is infiltration of lymphocytes into the lower epidermal layers with massive necrosis/apoptosis of keratinocytes, which is limited to the tips of rete ridges. Dermal lymphocytes are usually CD3⁺, CD4⁺, while most of the intraepidermal T cells are CD8⁺. Analysis of TCR-γ-chain gene rearrangement displayed polyclonality in all cases examined. Differential diagnosis mainly includes morphea, mycosis fungoides, annular erythemas and inflammatory lesions of vitiligo. Topical corticosteroids and topical tacrolimus represent the most effective drugs for ALDY treatment.

Annular lichenoid dermatitis of youth: a separate entity or on the spectrum of mycosis fungoides? Case report and review of the literature

Annular lichenoid dermatitis (ALDY) is a rare dermatosis that is most often seen in children and young adults and is characterized by annular patches with raised borders, most frequently on the trunk and the groin. A distinct lichenoid tissue reaction involving the base of the rete, resulting in squared-off rete ridges, helps to differentiate this from other lichenoid dermatoses and mycosis fungoides (MF). Herein, we report an additional case of this condition in a 7-year-boy, whose biopsy exhibited the typical quadrangular rete alteration and also contained distinct aggregates of CD8+ lymphocytes, Langerhans cells and colloid bodies within the involved rete. A literature review with emphasis on the clinical and histopathological differential diagnosis reveals additional clinical features of ALDY to potentially help differentiate this entity from annular presentations of mycosis fungoides.