Granuloma annulare is a benign, inflammatory skin condition that occurs in the deeper layer of the skin, the dermis. The cause is uncertain, however may be associated with systemic processes including hyperlipidemia and thyroid disease. Infectious aetiologies have been postulated, however studies are mixed.1
As the name suggests, granuloma annulare takes the form of ring-shaped (annular) smooth, red/pink or purple papules and plaques. It can occur anywhere on the body, but is more common over joints, backs of the hands, dorsum of the feet, or ankles. These can sometimes be mildly itchy but overall tend to be asymptomatic.
Localised granuloma annulare is more common in children and young adults, whereas the generalised form is more likely to be found in older adults. Women are affected twice as often as men. There is also an association with other autoimmune conditions such as diabetes mellitus and autoimmune thyroiditis1.
The diagnosis of granuloma annulare is typically made clinically, although sometimes biopsy may be required. This usually shows necrobiotic degeneration of dermal collagen surrounded by an inflammatory reaction.
In the vast majority of cases, no treatment is required, and the lesions resolve spontaneously, usually over a period of two years. In persistent lesions, topical corticosteroids can be trialled or cryotherapy may be of some benefit but does lead to permanent scarring.2 Majority of treatments for generalised form are not very effective including phototherapy and immunosuppression such as oral steroids/ cyclosporine etc. The risks versus the benefits of these treatments need to be weighed up on an individual basis.
N.B. Granuloma annulare is also known as necrobiotic papulosis.
References
1. Piette, E. W., & Rosenbach, M. (2016). Granuloma annulare: Pathogenesis, disease associations and triggers, and therapeutic options. Journal of the American Academy of Dermatology, 75(3), 467–479. https://doi.org/10.1016/j.jaad.2015.03.055
2. Wang, J., & Khachemoune, A. (2018). Granuloma annulare: a focused review of therapeutic options. American journal of clinical dermatology, 19(3), 333-344