Abstract
IntroductionPleural effusions are a common clinical problem and affect about one million people in the United States and United Kingdom each year. Over 60 causes of pleural effusion have been identified; establishing the definitive aetiology can be difficult, and often requires invasive procedures. Guidelines state that macroscopic examination of the fluid should be the first step in determining the aetiology of a pleural effusion. Papillary thyroid carcinoma is an uncommon cause of malignant pleural effusion, with only 10 cases reported in the literature, their physical characteristics and composition having been rarely described. We describe for the first time a distinctive brown colour of the malignant effusion (despite centrifugation) from a rare case of metastatic papillary thyroid cancer to the pleura, associated with a high pleural fluid iodine content. Such a characteristic may be useful in expediting diagnosis of a malignant pleural effusion in the appropriate clinical context.Case presentationWe present the case of a 71-year-old Caucasian man with metastatic papillary thyroid cancer; a large, long-standing, right-sided pleural effusion and a 83-fold higher pleural thyroglobulin level compared to corresponding serum, supporting this malignancy as the cause of the patient’s effusion. The pleural fluid had a distinctive pigmentation similar to iodine-containing antiseptic preparations. Biopsy during medical thoracoscopy confirmed metastatic papillary thyroid carcinoma. Analysis of pleural fluid showed a pleural thyroglobulin level over 80 times that of serum levels (29,000μg/L versus 350ug/L). Pleural fluid iodine content was 23,000ug/L and may account for the fluid’s distinctive pigment, as iodine is an essential component in thyroglobulin and thyroid hormone synthesis.ConclusionsPleural fluid pigmentation may aid diagnosis in the appropriate clinical setting. A distinctive iodine-like brown colour of pleural fluid may represent elevated iodine content and should raise consideration of metastatic thyroid cancer as a cause for a pleural effusion.
Highlights
Pleural effusions are a common clinical problem and affect about one million people in the United States and United Kingdom each year
Case presentation: We present the case of a 71-year-old Caucasian man with metastatic papillary thyroid cancer; a large, long-standing, right-sided pleural effusion and a 83-fold higher pleural thyroglobulin level compared to corresponding serum, supporting this malignancy as the cause of the patient’s effusion
Malignant pleural effusions are a common clinical problem, and a wide variety of malignancies can metastasise to the pleura
Summary
This case is the first to report high iodine content and an associated distinctive brown colour in the malignant effusion fluid from metastatic PTC. The usefulness of these findings in aiding diagnosis of metastatic pleural disease from PTC deserves investigation. Authors’ contributions AR analysed and interpreted the patient data regarding the pleural disease and fluid characteristics, reviewed the literature, and provided a major contribution to the writing of the manuscript. Author details 1Department of Respiratory Medicine, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth, WA 6009, Australia. Author details 1Department of Respiratory Medicine, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth, WA 6009, Australia. 2Department of Clinical Biochemistry, PathWest Laboratory Medicine WA, QEII Medical Centre, Hospital Avenue, Nedlands, Perth, WA 6009, Australia. 3Department of Medical Oncology, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, Perth, WA 6009, Australia. 4School of Medicine and Pharmacology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. 5Centre for Asthma, Allergy & Respiratory Research, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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