Pretibial Myxedema in a Euthyroid Patient

Area of Science:

• Endocrinology
• Dermatology

Background:

• Pretibial myxedema (PM) is a rare extrathyroidal manifestation of Graves' disease, affecting 0.5–4.3% of hyperthyroid patients.
• PM often co-occurs with thyroid orbitopathy and is typically associated with elevated thyroid antibodies, including thyroid peroxidase (TPO), thyroglobulin, and TSH receptor antibodies.

Observation:

• This report details a rare case of biopsy-proven pretibial myxedema.
• The patient was euthyroid and had no prior history of Graves' disease or Hashimoto's disease.

Findings:

• Thyroid peroxidase and thyroglobulin antibody levels were only slightly elevated.
• Thyroid-stimulating hormone receptor antibodies (thyrotrophin-binding inhibitor immunoglobulin) were negative.

Implications:

• This case highlights that pretibial myxedema can occur in euthyroid individuals without a history of autoimmune thyroid disease.
• The findings suggest a need to consider differential diagnoses for pretibial myxedema beyond typical associations with Graves' disease.