Parathyroid carcinoma co-occurring with parathyroid adenoma and papillary thyroid carcinoma: a rare case report with comprehensive literature review.

Parathyroid carcinoma is a rare endocrine malignancy with unclear etiology, and its clinical manifestations are often difficult to distinguish from parathyroid adenoma. The concurrent occurrence of parathyroid carcinoma, parathyroid adenoma, and thyroid carcinoma is an extremely uncommon clinical scenario. This study retrospectively analyzed the clinical data of a 44-year-old female patient with this concurrent condition who was treated at the Department of Thyroid Surgery, China-Japan Union Hospital of Jilin University. The patient underwent radical resection of left parathyroid carcinoma (including left thyroid lobectomy with isthmusectomy and central compartment lymph node dissection), excision of right parathyroid adenoma, and partial right thyroid lobectomy. Postoperative pathological examination confirmed the diagnoses of parathyroid carcinoma, parathyroid adenoma, thyroid malignant tumor, and nodular goiter. Preoperative diagnosis of this concurrent disease is highly challenging, and intraoperative pathological examination is often required for confirmation. Given the overlapping endocrine tumor patterns, this condition may be associated with underlying multiple endocrine neoplasia syndromes. Therefore, personalized treatment strategies combining precise surgery and long-term endocrine monitoring are crucial to achieve both oncological control and correction of hormonal dysregulation. This study aims to provide useful insights for clinical practice; we also conducted a literature review summarizing the reported features, diagnostic approaches, and treatment options for this condition.