We report a rare case of distant subcutaneous parathyroid carcinoma recurrence. A 50-year-old woman was referred to our hospital because of sustained hypercalcemia despite surgical removal of a parathyroid carcinoma. A focal uptake in the upper mediastinal area was detected in a 99mTc-sestamibi scan, and 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET)/computed tomography (CT) imaging demonstrated a subcutaneous mass. She underwent tumor resection, and the pathological findings were consistent with a parathyroid carcinoma. The postoperative serum parathyroid hormone (PTH) level remained within normal limits. However, a new palpable solitary mass was identified in the upper portion of the left breast 1 year postoperatively. Both a 99mTc-sestamibi scan and 18F-FDG PET/CT imaging revealed an abnormal lesion in the upper breast, and subsequent pathology reports confirmed parathyroid carcinoma metastasis. Serum PTH and calcium levels fell within normal ranges after tumor resection. Two subcutaneous recurrent lesions appeared likely due to tumor seeding during the previous endoscopic operation at a local hospital.
Biological Markers/blood ; Breast Neoplasms/blood/radiography/*radionuclide imaging/*secondary/surgery ; Carcinoma/blood/radiography/*radionuclide imaging/*secondary/surgery ; Female ; Fluorodeoxyglucose F18/*diagnostic use ; Humans ; Middle Aged ; Multimodal Imaging ; Parathyroid Hormone/blood ; Parathyroid Neoplasms/blood/*pathology/surgery ; *Positron-Emission Tomography ; Predictive Value of Tests ; Radiopharmaceuticals/*diagnostic use ; Technetium Tc 99m Sestamibi/*diagnostic use ; Time Factors ; *Tomography, X-Ray Computed ; Treatment Outcome