Anaplastic Transformation of Papillary Thyroid Carcinoma Only Seen in Pleural Metastasis: A Case Report with Review of the Literature

Abstract

Anaplastic transformation of papillary thyroid carcinoma (PTC) at distant metastatic sites is extremely rare, and there have been fewer than 20 reported cases in the literature. A 61-year-old woman presented with 1-week history of dyspnea. Her past medical history was remarkable because, 19 years ago, she underwent nearly total thyroidectomy and radical neck dissection due to PTC. Computed tomography of the chest revealed a 1.7 cm nodule in the lung and diffuse pleural thickening. Gun biopsy of the lung nodule revealed metastatic PTC with typical histology. However, the pleural biopsy predominantly showed anaplastic pleomorphic and spindle sarcomatoid carcinoma with microscopic focus of PTC. Immunohistochemical results showed both anaplastic sarcomatoid and PTC components positive for TTF-1, galectin-3 and PAX-8, thus supporting anaplastic transformation of PTC at the metastatic site. Subsequently the patient received 1 cycle of cisplatin-based chemotherapy but died from the disease 4 months after diagnosis. Although it is rare, anaplastic transformation of PTC should be considered during differential diagnosis of patients who present with exclusive sarcomatoid morphology at metastatic sites and have a history of PTC. We report another case of anaplastic transformation of PTC, found at pleural metastasis, together with the immunohistochemical profile and a literature review.

Pleural fluid due to papillary thyroid cancer

“…However, as this is a rare condition, standard therapy has not yet established. This case report documents our clinical experience, we present herein a patient with pleural fluid due to papillary thyroid cancer, and reviewed previously reported such cases (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”

“…Lung metastases of thyroid cancer are those to the lung parenchyma, such metastases usually have multiple small nodules in both lungs (1,2). On the contrary, however, pleural fluid due to thyroid cancer is a rare etiology, to our knowledge, and only 51 cases have been reported (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Pleural fluid due to thyroid cancer has been reported to be less than 1% in all the patients with malignant pleural fluids (4,11).…”

“…Papillary thyroid cancer was the major histologic type of thyroid cancer with pleural effusion, and other histologic types were few (3). Thyroid cancer patients with pleural fluid, regardless of tissue type, were long-term survivors (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). In general, diagnosis of malignant fluid is established by positive pathological findings using specimens from pleural fluid (20).…”

Anaplastic thyroid carcinoma mimicking a malignant pleural mesothelioma: Clues for diagnosis

“…2 Kim et al reviewed fewer than 20 reported cases of anaplastic transformation at different metastatic sites and found only one case of pleural thickening with pleural effusion in which diagnosis was made by pleural biopsies with immunohistochemical staining suggestive of both PTC and anaplastic components. 3 In our case, the clinical work-up was led by the diagnosis of a pleural exudate in an asbestos-exposed patient with a PET-CT evaluation mimicking a malignant pleural mesothelioma. It highlights the diagnostic difficulties in such situations of malignant pleural effusion in a patient with a previous history of PTC, in particular when a thoracoscopic assessment of the pleural cavity is not feasible.…”

“…Kim et al . reviewed fewer than 20 reported cases of anaplastic transformation at different metastatic sites and found only one case of pleural thickening with pleural effusion in which diagnosis was made by pleural biopsies with immunohistochemical staining suggestive of both PTC and anaplastic components …”