To investigate the clinical diagnostic characteristics of hypothyroidism pretibial myxedema (PM) after ¹³¹I treatment.

One case with clinical manifestations of symmetrical keloid-like PM was retrospectively analyzed.

The patient was treated by ¹³¹I for "hyperthyroidism" eight years ago, half a year after the treatment, the patient′s bilateral calves showed finger-like protrusions.On October 16, 2017, subcutaneous masses were seen on the bilateral anterior tibiae with size of 80 mm ×40 mm, and the skin showed keloid-like changes.Thyroid function showed free triiodothyronine (FT3)<2.12 pmol/L, free thyroxine (FT4)<4.12 pmol/L, thyrotropin (TSH)88.56 mU/L, anti-thyroid peroxidase antibody (TPOAb) 27.45 IU/ml, anti-thyroglobulin antibody (TgAb)<10.00 IU/ml, thyrotropin receptor antibody (TRAb) 15.31 IU/L and thyroglobulin (Tg) 9.89 μg/L.Thyroid color ultrasound showed thyroid atrophy with decreased blood supply.Postoperative pathology showed: skin tissue, a large number of dermal mucins deposition, morphology were consistent with anterior tibial mucoid edema.

The understanding of the clinical features and specific manifestations of anterior tibial myxedema can improve the diagnostic accuracy and guide clinical treatment.