Endocrine Abstracts

A 87 year old woman admitted with complaints of hoarseness and a palpable mass which she noticed 1 week ago. She had hypothyroidism for 25 years. On examination, there was a hard and fixed palpable 4x4 cm mass on the right side of the neck. In laboratory evaluation, thyroid function tests were normal, thyroid auto-antibodies were positive, calcitonin was normal, C-reactive protein was 224 mg/l and liver and kidney function tests were normal. Thyroid ultrasonography revealed a 27.5x51.1x61.0mm isoechoic nodule containing macrocalcifications and areas of cystic degeneration completely filling the right lobe. Fine needle aspiration biopsy(FNAB) of the nodule was reported as atypia of undetermined significance. In the second FNAB;there were atypical cells with spindle cytoplasm, isolated spindle cells described in fibrin in the cell block with necrosis. The specimen was evaluated as suspicious for malignancy. Lymphoid malignancies were ruled out with flow cytometric analysis. The patient was hospitalized with a prediagnosis of anaplastic thyroid cancer. Neck MRI detected a 9.0x6.5x6.5 cm centrally necrotized mass surrounding right common carotid artery. In 18-FDG-PET-CT scanning, uptake of the lesion was significantly increased and there were multiple metastatic nodules in the lung. A tru-cut biopsy was performed. ‘In cytopathologic evaluation, neoplastic infiltration consisting of fascicular shapes was observed within a fibrous stroma. Spindle cells arranged in ‘herringbone pattern was observed. A large number of mitotic figures drew attention. In the immunohistochemical study, no staining was detected with TTF-1, CD34, PAX-8, CK-7, p63, SMA, desmin, FL-1, S100, synaptophysin and calcitonin. Staining with vimentin was detected. The Ki-67 proliferation index was 90%. BRAF mutation was negative.’ A primary malignant fibrosarcoma of thyroid gland was considered. Because of the advanced age and poor general performance of the patient; chemotherapy and surgery were not considered. 10 sessions of radiotherapy was started. Malignant mesenchymal tumors of thyroid gland comprise 0.3% of all malignant thyroid tumours(1). Fibrosarcomas consist 9.2% of primary malignant mesenchymal tumors of thyroid(2). Although the initial diagnosis that comes to mind in a hard, fixed and rapidly-growing thyroid cancer is anaplastic cancer, malignant mesenchymal tumors like fibrosarcoma should also be considered in differential diagnosis.

References: 1. Bula G, Waler J, Niemiec A, Trompeta J, Steplewska K, Gawrychowski J. Unusual malignant thyroid tumours—a clinical study of 20 cases. Acta Chirurgica Belgica 2008; 108: 702–07.

2. Surov A, Gottschling S, Wienke A, Meyer HJ, Spielmann RP, Dralle H. Primary thyroid sarcoma: a systematic review. Anticancer research. 2015;35(10):5185-91