Subcutaneous granuloma annulare: MR imaging features in six children and literature review.

Abstract

To describe the magnetic resonance (MR) imaging findings of subcutaneous granuloma annulare (SGA), a rare mass of early childhood. MR imaging studies and clinical records in six children aged 2 1/2-4 years in whom SGA was diagnosed between 1993 and 1997 were retrospectively reviewed. All MR imaging examinations included T1-weighted and fast spin-echo T2-weighted sequences. Three children received intravenous contrast material. The diagnosis was established by using excisional biopsy results, with confirmation by means of characteristic features in mucin-stained specimens. All children presented with a nontender, nonmobile mass. The lesion in all six children was confined to the pretibial (n = 5) or prepatellar (n = 1) soft tissues. MR imaging characteristics were uniform. Masses were subcutaneous in location and had ill-defined margins. On T1-weighted images, the lesion was isointense or slightly hyperintense to muscle. On T2-weighted images, the signal intensity was more heterogeneous, but the lesion was predominantly hyperintense. In three children who received contrast material, the lesion enhanced nearly homogeneously. Although SGA can often be diagnosed on the basis of clinical characteristics, MR imaging may be requested by practitioners unfamiliar with the lesion. In these cases, with recognition of typical MR imaging features, a limited biopsy and specific histologic preparation that includes mucin staining can be recommended.