Uncommon Non-Infectious Annular Dermatoses.

Several cutaneous diseases can present with annular lesions, making a distinction by physical appearance alone challenging. They can be distinguished into infectious and non-infectious, and common and uncommon annular dermatoses. Common non-infectious diseases include granuloma annulare, urticaria, and subacute lupus erythematosus. In addition, there are rare non-infectious non-neoplastic annular dermatoses whose nosographic attribution is established, including annually recurring erythema annulare centrifugum (EAC) and annular erythema in Sjögren syndrome and others whose nosographic positioning is still debated. They are neutrophilic figurate erythema, palpable migratory arciform erythema, eosinophilic annular erythema, and annular lichenoid dermatitis of youth. Their etiopathogenesis is largely unknown, although immune-mediated mechanisms are likely involved. It is difficult to establish if they are variants of reaction patterns or separate clinic-pathological entities. In fact, EAC and annually recurring EAC may represent different aspects of the same disease. Palpable migratory arciform erythema is hardly distinguishable from EAC deep type, Jessner-Kanof disease, and lupus tumidus. Neutrophilic figurate erythema and eosinophilic figurate erythema are clinically very similar and differing only in the relative proportion of eosinophils and neutrophils.