Endocrine Abstracts

Background: Differentiated thyroid cancers are reported to present with synchronous distant metastases in 1–9% of cases. The most common single sites of synchronous metastases are lung (45%) and bone (39%) with dual site involvement (12%). Other single sites of metastases are rare (4%). Pleural metastases are very unusual, accounting for < 0.6% of cases.

Case: A 55-year-old male smoker presented with cough, weight loss and thoracic back pain. Examination demonstrated a firm 2 cm right thyroid mass with no palpable lymphadenopathy. CT imaging revealed a right sided, 6 cm pulmonary mass, multiple pulmonary nodules, a pleural effusion and likely bone metastases. Both core needle biopsy of the pulmonary mass and a pleural biopsy stained positive for thyroglobulin and TTF1 and negative for CEA and PSA suggesting metastatic papillary thyroid carcinoma. Ultrasound revealed a nodular thyroid, cytology Thy 3a. The patient underwent a total thyroidectomy with right sided level II–IV lymph node dissection, left sided level VI dissection, resection of the lung right lower lobe and a hilar lymph node clearance. Histology revealed conventional type papillary thyroid carcinoma pT4 N1 (6/53) M1. The resected lung lesion demonstrated metastatic papillary thyroid carcinoma with involvement of sub-pleural and septal lymphatics, infiltration of the visceral pleura and metastastic involvement of local lymph nodes. Post-operatively the patient underwent I131 ablation therapy (8000 MBq). Therapeutic uptake was seen in the pleural and skeletal metastases with radiological progression of relatively iodine poor pulmonary metastases. FDG-PET eight weeks post-therapy showed disease response in the pleura with residual active disease at other sites.

Conclusion: We report a patient presenting with metastatic papillary thyroid carcinoma with pleural, pulmonary and bone metastases. Pleural metastases are a rare site of metastatic spread and are associated with a poor prognosis (median 27 months).