[A case of diffuse fasciitis and its MRI findings]

A 36-year-old woman with diffuse fasciitis and her MRI findings are reported. The patient developed pain and swelling in the calves, right forearm, and left arm, predominantly in the right calf muscle. Her body temperature was 38.4 degrees C, the ESR 104 mm/2 hours and white blood cell count 8,000/microliter without eosinophilia. The fascia and muscle were biopsied from her right calf. The light microscopy showed that the fascia was thickened and infiltrated with mononuclear cells with no eosinophils, mostly in perivascular areas. The muscle fibers were spared. MRI of legs revealed marked hyperintensities on T2 and mild hyperintensities on T1-weighted images in the fascia, superficial flexor muscles, especially soleus muscle, and Achilles tendons. Moderate dose of prednisolone was very effective and the abnormal signals on MRI almost disappeared within a month. T2 weighted MRI was very useful to detect the lesions and to evaluate the course of diffuse fasciitis.