A 36-year-old man with ulcerative colitis presented with bloody stools at the beginning of October 2020. His condition had been stable without treatment since diagnosis 4 years prior. He was administered 4,000 mg of salazosulfapyridine orally and the bloody stools resolved. Fifteen days after treatment, he was admitted to our hospital with swelling and pain in his right lower leg. Laboratory results revealed an elevated erythrocyte sedimentation rate (43 mm/hr) and mildly elevated C-reactive protein levels (4.08 mg/dl). His D-dimer level was also elevated at 7.6 μg/ml. MRI using fat saturated T2-weighted imaging demonstrated marked hyperintensity in the fascia of the lower leg flexor and blood vessels of interstitial. In gadolinium-enhanced T1-weighted images, the deep veins were found to be dilated and the vein walls and their surrounding areas strongly contrasted, suggestive of localized fasciitis. No abnormalities were found on biopsy of his right gastrocnemius muscle on the 5th day after admission. Two days after the muscle biopsy, the patient began experiencing swelling and pain in his left lower leg. The high intensity lesions in his right leg were reduced on MRI performed the same day, but that of the fascia between the left gastrocnemius and soleus muscles was noted. We administered 60 mg (1.0 mg/kg/day) of prednisolone orally on day 9 and the pain and swelling in both legs promptly resolved. The prednisolone was tapered to 5 mg/day and as of the time of writing, resolution of pain and swelling has been maintained. Gastrocnemius myalgia syndrome, which causes pain and localized fasciitis, is often reported as a complication of Crohn's disease but is rare in conjunction with ulcerative colitis. It is important that clinicians are aware of this syndrome so it can be recognized early and successfully treated.
Keywords: gastrocnemius myalgia syndrome; prednisolone; ulcerative colitis.