Parathyroid hyperplasia shown on (99m)Tc-HYNIC-TOC scan.

Area of Science:

• Endocrinology
• Nuclear Medicine
• Oncology

Background:

• Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome often caused by phosphaturic mesenchymal tumors.
• Hypercalcemia and hypophosphatemia are key biochemical indicators that warrant investigation for TIO.
• Accurate localization of the causative lesion is crucial for effective management.

Observation:

• A 68-year-old patient presented with hypercalcemia and borderline hypophosphatemia, suspected of having TIO.
• Tc-HYNIC-TOC scintigraphy was employed to identify the source of the suspected tumor.
• Imaging demonstrated increased radiotracer uptake in the upper mediastinum and focal pancreatic activity.

Findings:

• Pathological examination confirmed parathyroid hyperplasia in the upper mediastinum.
• The patient was diagnosed with multiple endocrine neoplasia type 1 (MEN-1 syndrome).
• The scintigraphy successfully localized the hyperplastic parathyroid tissue responsible for the paraneoplastic syndrome.

Implications:

• Tc-HYNIC-TOC scintigraphy is a valuable tool for diagnosing TIO, particularly when the causative lesion is not readily apparent.
• This case highlights the utility of nuclear imaging in identifying ectopic hormone production.
• Early and accurate diagnosis through advanced imaging can lead to timely intervention and improved patient outcomes in MEN-1 syndrome.