INTRODUCTION: Papillary Carcinoma is the most common thyroid cancer and has an overall 10-year survival of over 90%. Distant spread is rare and most common sites of metastasis are lung and bone. We report a case of papillary cancer of thyroid successfully treated 26 years ago recurring with pleural metastasis.
CASE PRESENTATION: A 44-year-old female presented with dyspnea on exertion and dry cough progressively worsening over last 4 months. She had Papillary carcinoma of thyroid, treated by total thyroidectomy and radioiodine 23 years prior to presentation. She was treated with Levothyroxine for TSH suppression. She had a history of 25 pack-year tobacco smoking. Her CXR showed large right pleural effusion. The pleural fluid was sterile exudate with 28% eosinophils. Pleural fluid cytology was highly suspicious for malignancy and showed papillary groups of atypical cells with associated psammoma bodies. CT scan of the chest revealed soft tissue densities in the right lung along the pleura. Video assisted thoracoscopy confirmed the multiple pleural based nodules and she underwent decortication and talc pleurodesis. Pathology confirmed well-differentiated papillary carcinoma with psammoma bodies, metastatic to pleura. Positive immunostaining for TTF-1, thyroglobulin, CK 19, CAM 5.2, CK 7 and E Cadherin was noted. CK20 immunostaining was negative as was Calretinin, later ruling against ovarian origin. Thyroglobulin level was grossly elevated [764ng/ml]. No thyroid tissue was seen by neck Ultrasound. I-123 scanning showed focal area of increased uptake in the right mid lung field. Patient subsequently underwent treatment with I-131.
DISCUSSIONS: Malignant pleural effusion occurs most commonly due to cancers of lung, breast, genitourinary or GI tract and lymphoma. Most of the other malignant pleural effusions are caused by tumors of unknown primary. First case of thyroid caner metastatic to pleura was reported in 1992 describing clinically evident pleural metastasis and presence of psammoma bodies in pleural effusion. Malignant pleural effusion complicates less than 1% of patients with papillary thyroid cancer and preceded death by median of 11 months. Papillary carcinoma of thyroid can metastasize many years after initial diagnosis; therefore patients treated for thyroid cancer should be followed with thyroglobulin level and radioiodine scan should be done if elevated.
CONCLUSION: We believe this is the longest time for recurrence of thyroid cancer. This is also very rare site for metastasis and is the second well-described case of pleural metastasis from papillary cancer of thyroid. The presence of 28% eosinophils in this case, proves that large amount of pleural fluid eosinophilia cannot rule out malignancy.
DISCLOSURE: Uday Mundathaje, None.