Diagnostic Challenges of Thyrotropin-Secreting Hypophyseal Macroadenoma Associated with Papillary Thyroid Carcinoma: Case Report and Literature Review.

Background and Clinical Significance: The concurrent presence of a thyrotropin-secreting hypophyseal adenoma (TSHoma) with a thyroid malignancy, such as papillary thyroid carcinoma (PTC), is exceptionally rare and significantly complicates clinical diagnosis and management. This rare combination raises difficult decisions regarding the treatment sequence and carries the risk of exacerbating either or both conditions. Case report: We present the case of a 59-year-old female patient exhibiting persistent hyperthyroid symptoms with unusually normal TSH levels despite elevated thyroid hormone concentrations. Initial diagnostic imaging revealed a hypophyseal macroadenoma and a diffuse nodular goiter. After the macroadenoma diagnosis, the patient initially refused surgical intervention, and subsequent dopamine agonist therapy proved ineffective. Eight years later, during a routine follow-up, a thyroid ultrasound revealed a diffuse nodular goiter classified as EU-TIRADS 5, and papillary thyroid carcinoma was confirmed through fine needle aspiration biopsy. A total thyroidectomy and subsequent radioactive iodine therapy were performed. However, persistently elevated postoperative TSH levels remained despite high-dose levothyroxine therapy. Due to the increased risk of malignancy recurrence associated with elevated TSH levels, the patient consented to macroadenoma surgery. A successful transsphenoidal macroadenomectomy stabilized the patient's condition, allowing for the normalization of TSH levels. Conclusions: This case underscores the importance of accurate differential diagnosis and highlights the challenges in managing TSH levels in patients with coexisting thyroid malignancies. With there being no clear guidelines for managing the combination of these conditions, decisions regarding treatment priority should consider the patient's preferences, the risk of malignancy recurrence or progression, neurological symptoms, and the aggressiveness of the thyroid tumor.