Large intrathymic parathyroid adenoma with hyperparathyroidism: a case report and review of the literature.

INTRODUCTION AND

IMPORTANCE

Primary hyperparathyroidism is most commonly caused by a cervical parathyroid adenoma; however, ectopic mediastinal lesions may delay diagnosis when neck imaging is negative.

CASE PRESENTATION: A 19-year-old woman presented with 4 years of progressive bone pain and osteoporosis with neuropsychiatric and gastrointestinal symptoms. Laboratory testing showed hypercalcemia (13 mg/dL) and markedly elevated PTH (614 pg/mL). Neck ultrasound and cervical CT were nondiagnostic. Technetium-99m sestamibi SPECT/CT localized a 38 × 40 mm hyperfunctioning lesion in the left anterior mediastinum. Initial video-assisted thoracoscopic surgery exploration failed to access the lesion; definitive resection was achieved via partial median sternotomy. Histopathology confirmed an intrathymic parathyroid adenoma. Postoperatively, calcium normalized and PTH decreased to 14 pg/mL with complete symptom resolution.

CLINICAL DISCUSSION: This case highlights the diagnostic pathway for suspected ectopic parathyroid disease following negative cervical imaging and the need to individualize surgical access for deep mediastinal lesions.

CONCLUSION

Mediastinal intrathymic parathyroid adenomas, although rare, should be considered in cases of persistent hyperparathyroidism with negative neck imaging. SPECT/CT is valuable for localization, and tailored surgical approaches can achieve a definitive cure.