SUBCUTANEOUS GRANULOMA-ANNULARE - RADIOLOGIC APPEARANCE

Objective. Granuloma annulare is an uncommon benign inflammatory derma tosis characterized by the formation of dermal papules with a tendency to form rings. There are several clinically distinct forms. The subcu taneous form is the most frequently encountered by radiologists, with the lesion presenting as a superficial mass. There are only a few scat tered reports of the imaging appearance of this entity in the literatu re. We report the radiologic appearance of five cases of subcutaneous granuloma annulare. Design and patients. The radiologic images of five patients (three male, two female) with subcutaneous granuloma annular e were retrospectively studied. Mean patient age was 6.4 years (range, 2-13 years). The lesions occurred in the lower leg (two), foot, forea rm, and hand. MR images were available for all lesions, gadolinium-enh anced imaging in three cases, radiographs in four, and bone scintigrap hy in one. Results. Radiographs showed unmineralized nodular masses lo calized to the subcutaneous adipose tissue. The size range, in greates t dimension on imaging studies, was 1-4 cm. MR images show a mass with relatively decreased signal intensity on all pulse sequences, with va riable but generally relatively well defined margins. There was extens ive diffuse enhancement following gadolinium administration. Conclusio n. The radiologic appearance of subcutaneous granuloma annulare is cha racteristic, typically demonstrating a nodular soft-tissue mass involv ing the subcutaneous adipose tissue. MR images show a mass with relati vely decreased signal intensity on all pulse sequences and variable bu t generally well defined margins. There is extensive diffuse enhanceme nt following gadolinium administration. Radiographs show a soft-tissue mass or soft-tissue swelling without evidence of bone involvement or mineralization. This radiologic appearance in a young individual is hi ghly suggestive of subcutaneous granuloma annulare.