A 46-year-old woman came with multiple asymptomatic skin-colored nodules over the right ring finger from 3 years. Clinical examination revealed multiple skin-colored, non-tender, firm to hard nodules of varying sizes located over the dorsum of the right ring finger. She was diagnosed with Subcutaneous or deep granuloma annulare.

Granuloma annulare is a common, asymptomatic benign inflammatory skin disease of unknown etiology seen in children and adults. It is characterized by an annular arrangement of erythematous papules, plaques, nodules or patches. The main clinical variants of granuloma annulare include localized, generalized, papular, umblicated, perforating and subcutaneous. SGA occurs usually in children and consists of deep dermal or subcutaneous nodules. 

SGA usually involves the subcutaneous tissue with or without involvement of the deep dermis. However, the involvement of more superficial dermal components has been reported in 25% of subcutaneous GA lesions, which may clinically manifest as erythematous to tan discolorations in the surface skin or superficial papules overlying the subcutaneous nodules.

Since SGA occurs almost exclusively in infants and children with maximum frequency between the ages of 3 and 6 years, the present case is unusual because it had onset in adulthood. The presence of acral, isolated, clustered deep granuloma annulare lesions confined to a single digit without classical GA lesions elsewhere is a rare finding. Such a case may mimic multiple osteomas, enchondromas, rheumatoid nodules and giant cell tumor of a tendon sheath. Such cases have rarely been reported in the literature.

GA is a collagenolytic or necrobiotic non-infectious granuloma wherein palisaded or interstitial type of granulomatous infiltrate develops around a central area of altered collagen and elastic fibers. A clue to differentiate GA from a rheumatoid nodule may be the presence of prominent mucin and a paucity of foreign body giant cells. 

Various treatment modalities are available for the treatment of GA including topical or intralesional steroids. The use of systemic agents such as systemic steroids, UV-A, isotretinoin, interferon gamma, and photodynamic therapy.

It frequently poses a diagnostic challenge and commonly mistaken for its clinical simulator rheumatoid nodule. Hence, it is essential to keep in mind SGA as a differential diagnosis when encountered with nodular lesions on acral areas in adults.

Suggested reading

1. Asymptomatic papulo-nodules localized to one finger. Indian J Dermatol 2015;60:522
2. Mutasim DF, Bridges AG. Patch granuloma annulare: Clinicopathologic study of 6 patients. J Am Acad Dermatol 2000;42:417-21.  
3. Misago N, Narisawa Y. Subcutaneous granuloma annulare with overlying localized granuloma annulare. J Dermatol 2010;37:755-7