Plantar fibromatosis: a benign aggressive neoplasm with a characteristic appearance on MR images.

PURPOSE: To define the magnetic resonance (MR) imaging characteristics of plantar fibromatosis.

MATERIALS AND METHODS: Sixteen patients (19 feet) with proved plantar fibromatosis underwent preoperative MR imaging at 1.5 T. A control group of 19 people (24 feet) also underwent MR imaging.

RESULTS: Twenty-seven lesions (mean size, 2.2 x 1.0 cm) were identified. All had infiltrative upper margins. Four (15%) of the 27 grew deep to the aponeurosis; 25 (92%) exhibited some signal intensity heterogeneity. All 27 of the lesions on T1-weighted conventional spin-echo (SE) images, seven (78%) of the nine on T2-weighted conventional SE images, and 17 (94%) of the 18 on T2-weighted fast SE images were isointense to minimally hyperintense (to the signal intensity of adjacent muscle). Five (83%) of the six lesions on short inversion time inversion-recovery images were hyperintense. Enhancement was variable on contrast material-enhanced images; nine (60%) of the 15 lesions on these images showed marked enhancement.

CONCLUSION: Plantar fibromatosis is a benign but infiltrative neoplasm with a characteristic location and appearance on MR images.