PMC8719313_01
Clinical characteristics of the sarcomatoid parathyroid carcinoma (SaPC) case. (A) Neck CT showed the giant tumor. (B) Tc-99m sestamibi scintigraphy suggests abnormal nuclide uptake in the left thyroid. (C) Chest CT presented micro pulmonary nodule before surgery. (D) The profile of the resected tumor. (E) Chest CT shows pulmonary metastasis at the closely located position in preoperative chest CT (C). (F) Enhanced MRI showed extensive local organ and tissue invasion.
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Ultrasonography showed that the left thyroid lobe was enlarged significantly, a hypoechoic lesion nearly occupied the whole lobe, and comparable signs were presented on the neck CT ( Figure 1A ). Tc-99m sestamibi scintigraphy demonstrated two-phase nuclide accumulation on the left thyroid ( Figure 1B ). Chest CT showed multiple micro pulmonary nodules ( Figure 1C ). The tumor profile showed that the thyroid was markedly infiltrated, and the normal gland was almost invisible ( Figure 1D ). Serum calcium and PTH levels were without abnormal elevation during this time ( Figure S1 ). Clinical examinations suggested regional relapse and multiple pulmonary metastases ( Figure 1E ). Enhanced MRI showed extensive local organ and tissue invasion by the recurred tumor ( Figure 1F ).
Pathological characteristics of the sarcomatoid parathyroid carcinoma (SaPC) case. (A) Negative staining of parafibromin in the nucleus (thick arrow) and contrast-positive staining (thin arrow) of parathyroid carcinoma (PC) cells (x630). (B) Spindle cells shuttled through carcinomatous component regions showed positive desmin staining (x200). (C) The morphology of cell changes between two component regions (arrow) (H&E, x400). (D) N-cad was positive in carcinomatous (thick arrow) and spindle cell components (thin arrow) (x200).
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Immunohistochemical staining was further performed to confirm the diagnosis ( Figure 2 ); results were presented below: (1) Carcinomatous components: Some PC cells show negative nuclear staining of parafibromin ( Figure 2A ); Cytokeratin (AE1/AE3) (+); Chromogranin A (+); E-Cadherin (+); PTH (+); Calcitonin (-); Thyroglobulin (-); Desmin (-); KI-67 index 10%; (2) Spindle cell components: Desmin (+;  Figure 2B ); Cytokeratin (AE1/AE3) (-); Chromogranin A (-); E-Cadherin (-); Calcitonin (-); KI-67 index 30%. In addition, the existence of transition zones ( Figure 2C ) and positive N-cad staining in both carcinomatous and sarcomatoid components ( Figure 2D ) was found during pathological examination.