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.