February 2017 | Case of the Month

The diagnosis is granuloma annulare.
 

Background

• Granuloma annulare (GA) is a relatively common condition that occurs in all age groups, but is rare in infancy. Although there are several clinical patterns, the typical lesion of GA is a smooth, annular plaque with a bumpy (papular) edge. The precise cause of GA is unknown. Histological examination reveals foci of degenerative collagen associated with palisaded granulomatous inflammation.

History

• GA affects all age groups, but is rare in infancy. It is most common in young adults. It is twice as common in women as in men
• Lesions evolve slowly and tend to be asymptomatic
   

Examination

• GA can affect any body site, although the dorsa of the hands and feet, as well as other extensor surfaces, are most commonly affected. There tends to be one to several lesions, although occasionally they can be numerous and widespread
• Lesions are made up of smooth, skin-coloured, or pink-red papules with no scale or other surface change. The characteristic lesion is a smooth, annular plaque that enlarges centrifugally with 'bumpy' papules around the periphery. Lesions may reach several cm in diameter
   

Differential diagnosis

• GA is sometimes mistaken for tinea or an annular erythema, although these are more inflammatory and have epidermal changes such as scaling. Other annular lesions, such as annular lichen planus, and occasionally sarcoid, can take on a similar appearance
   

Management

• For the vast majority of cases no treatment is required given that the natural tendency for lesions is to resolve spontaneously (in 50% of patients lesions resolve within two years, although they can recur), and there is limited evidence that treatment is beneficial
• Potent topical steroids, and occasionally phototherapy for widespread lesions, are occasionally used
   

Please refer to the chapter on granuloma annulare to read more about this condition including its less common presentations.