Primary Sarcomas of Thyroid Gland-Series of Three Cases with Brief Review of Spindle Cell Lesions of Thyroid

Abstract

Primary Malignant Fibrous Histiocytoma (MFH-T) and Leiomyosarcoma (LMS-T) of the thyroid gland are extremely rare tumors. Very few cases have been reported in the literature. Both entities occur more commonly in women than men. The closest clinical and histological differential diagnosis is anaplastic carcinoma of thyroid. We present three cases of rare primary sarcomas of thyroid gland. Case-1 was a 63-year-old woman and Case-2 was a 52-year-old woman. Both of them presented with a rapidly increasing thyroid mass clinically mimicking anaplastic carcinoma (AC-T). Both the patients developed pulmonary metastasis and succumbed to the illness soon after the diagnosis of MFH-T was made. Case 3 was 65-year-old woman with neck swelling since six months diagnosed as LMS-T. The present communication adds three new cases to the literature on sarcomas of thyroid gland with an emphasis on differential diagnosis of spindle cell lesions of thyroid. MFH-T and LMS-T needs to be differentiated from AC-T, metastatic sarcomas, spindle cell variant of medullary carcinoma, synovial sarcoma, fibrosarcoma; final diagnosis rests on histopathology and immunohistochemistry.

Keywords: Leiomyosarcoma thyroid; Malignant fibrous histiocytoma thyroid; Sarcoma thyroid; Thyroid mass lesion.

[Table/Fig-1]:

(a) Case 1: Old lady with a huge neck mass. (b) Neck CT: thyroid mass with necrosis and calcification compressing trachea (Arrow). Inset: Neck X-ray showing similar changes. (Arrow)

[Table/Fig-2]:

(a) Case 1-FNAC smears show spindle shaped cells with moderate degree of atypia, hyperchromatic nucleus and 1-2 prominent nucleoli. [Giemsa, x200] (b) Gross: Tumor is haemorrhagic with areas of congestion. Inset: Cut section: grey white with necrotic and haemorrhagic areas. (c) Diffuse sheets of spindle cells; normal thyroid follicles were identified interspersed between the tumor cells (arrow). (H&E, x200) Inset: An intact capsule was identified around the tumor mass; cells arranged in a vague storiform pattern. (H&E x100).

[Table/Fig-3]:

(a) Case 2-Gross: Thyroid gland is replaced by tumor with areas of necrosis. (b) Tumor cells arranged in storiform pattern (Arrow) (H&E, x400). Inset: FNAC smears show scattered atypical spindle cells with focal areas of necrosis (Giemsa, x40). (c): Tumor cells in sheets with areas of necrosis. (Arrow) (H&E, x200). (d) Tumor cells express CD 68 (Immunohistochemistry with DAB as chromogen x400); Inset: Vimentin positive tumor cells (x100).

[Table/Fig-4]:

(a) Case 2-Diffuse Vimentin positivity. (Immunohistochemistry with DAB as chromogen x400) Inset: CD-68 positive tumor cells. (Immunohistochemistry with DAB as chromogen x100) (b) Cytokeratin positive remnant thyroid follicles. (Immunohistochemistry with DAB as chromogen x400) Inset: Thryroglobulin positive remnant thyroid follicles (Immunohistochemistry with DAB as chromogen x200).

[Table/Fig-5]:

(a) Case 3- CT scan: heterogeneous enhancing mass in thyroid gland with solid areas and necrosis in the centre. (b) Positron emission tomography scan- heterogeneous uptake in thyroid gland right lobe and isthmus. (c) Gross-tumor is replacing whole of thyroid gland. Cut section: Grey white to yellow, firm lobulated mass.

[Table/Fig-6]:

(a) Case 3-Spindle cells in sheets and whorls replacing whole of thyroid gland. (H&E, x200): 6b) Large areas of necrosis (arrow) with neutrophilic infiltrate (H&E x200).

[Table/Fig-7]:

(a) Case 3-Cigar shaped nucleus and mild pleomorphism with thyroid follicles at periphery (H&E x200); (b) Residual normal thyroid follicles in between tumor cells (H&E x200); (c) Tumor cells are immunoreactive for Smooth muscle actin. (Immunohistochemistry with DAB as chromogen x200); (d) -Tumor cells do not express thyroglobulin; residual follicles immunoreactive for Throglobulin (Immunohistochemistry with DAB as chromogen x200).