Endocrine Abstracts

Purpose

Poorly differentiated thyroid carcinoma (PDTC); is a rare type of thyroid cancer with a high risk of recurrence, metastasis, and death. Pleural effusion due to thyroid cancer has seldom been reported. In this report, we present a case with PDTC related malignant pleural effusion.

Case

A 66-year-old male patient presented with neck swelling and shortness of breath. At another center, thyroid ultrasonography revealed a multinodular goiter and an irregularly circumscribed lymphadenopathy on the left level IV. He had multiple lung metastases in thorax computed tomography (CT). Positron emission tomography/computed tomography (PET-CT) detected “hypermetabolism in malignant nodules in the thyroid, multiple metastatic lymph nodes in the neck and bilateral metastatic lung nodules.” Cytology of lymph nodes at the right level 3, 4, 6–2a junction was malignant. The patient underwent bilateral total thyroidectomy, bilateral central lymph node dissection, and right modified radical neck dissection with a final pathologic diagnosis of “poorly differentiated thyroid carcinoma, right lateral and central tumor positive lymph node.” Upon persistence of dyspnea, thoracentesis was performed for a left-sided pleural effusion, which in the end had exudative characteristics. [blood thyroglobulin (Tg): 23960 ng/ml, Tg with pleural fluid dilution > 30000 ng/ml]. Cytology confirmed carcinoma infiltration. In the follow-up, mediastinal, lung, and pleural metastases in addition to effusion in the left hemithorax persisted. We performed pleurodesis after the initial tube thoracostomy. During follow-up pleural fluid cell-block was performed due to continued pleural effusion and reported as carcinoma metastasis. 200 mCi RAI treatment was given after preparation with recombinant thyroid stimulating hormone (TSH). After the comparative PET-CT revealed progression, transthoracic lung biopsy performed and reported as carcinoma metastasis. After these results tyrosine kinase inhibitör (sorafenib) was initiated to the patient.

Conclusion

The most common sites of distant metastasis of PDTC are the lungs and bones. It constitutes about 85% of deaths related to the disease. Less than 1% of malignant pleural effusions are associated with thyroid cancers. Pleural fluid thyroglobulin level and immunohistochemical staining may enhance the diagnostic process.