Presented by: Christine Shaver, MD, Wei Teresa Hsu, MD, and Carrie Ann Cusack, MD
Drexel University College of Medicine
May 16, 2016
Granuloma annulare is a benign inflammatory dermatosis that was initially described in 1895 by T. Colcott Fox and was later named granuloma annulare in 1902 by Radcliffe-Crocker. There is no ethnic or geographic predominance; however, women are affected twice as often as men.
The pathogenesis is poorly elucidated, but theories include a reactive type-4 cellular immunity, immune complex vasculitis, tissue monocyte abnormalities, and complex immune responses related to a primary disorder of connective tissue degeneration. While the cause of the condition is generally unknown, it is clinically well-characterized by pink-red papules and plaques with elevated borders. It can occur in a wide variety of age groups and many clinical variants exist.
The most common form of granuloma annulare is the localized type. This type commonly occurs in children and in adults less than 30 years old, with a predilection for the feet, ankles, lower limbs, and wrists. In contrast, generalized granuloma annulare occurs in a bimodal distribution in patients less than 10 years and in adults between 30-60 years old. The lesions can vary widely in color and size. While subcutaneous GA can be seen in adults, it is often found in healthy children aged 2-10 years old. It is most prevalent on the anterotibial plateau, ankles, dorsal feet, buttocks, hands, scalp, and eyelids. More rare types of GA include perforating GA, which often heals with scarring and is found in children, and arcuate GA, which is distinguished by large plaques with prominent central clearing.
Granuloma annulare has been associated with a variety of factors and underlying conditions including tuberculosis, arthropod bites, trauma, sun, thyroid conditions, vaccinations, and viral infections, although no strong linkage has been demonstrated. There does appear to be an increased incidence of GA in patients who have thyroiditis and type I diabetes.
Histopathologically, GA is defined by the presence of foci of degenerated collagen with associated peripheral palisading granulomas in the superficial dermis.
While laboratory studies are not uniformly suggested, they may include CBC, CMP, thyroid studies, and HgbA1C. Imaging studies are not necessary for diagnosis, however may be helpful in the evaluation of deep subcutaneous lesions if suspected based on thorough history and physical examination. Biopsy is recommended for atypical presentations or those that are persistently resistant to treatment.
Treatment varies based on the type of GA that is diagnosed. Forms of localized GA often will resolve spontaneously and do not need treatment. When necessary, treatment may include potent topical or intralesional corticosteroids and cryotherapy. Generalized GA is often more difficult to treat given the surface area involved, but successful treatment has been observed with isotretinoin and PUVA. Smaller case reports have shown improvement with dapsone, nbUVB, systemic steroids, hydroxychloroquine and cyclosporine.
Gloster Jr, Hugh Morris, Lauren E. Gebauer, and Rachel L. Mistur. “Granuloma Annulare.” Absolute Dermatology Review. Springer International Publishing, 2016. 503-505.
Thornsberry, Laura A., and Joseph C. English III. “Etiology, diagnosis, and therapeutic management of granuloma annulare: an update.” American journal of clinical dermatology 14.4 (2013): 279-290.
Patrizi, A., C. Gurioli, and I. Neri. “Childhood granuloma annulare: a review.”differences 9 (2014): 10.