Giant cell tumor of soft tissue originating from the thyroid: a case report and literature review

Abstract Background: Giant cell tumor of soft tissues (GCT-ST) is a low malignant uncommon neoplasm, with is histological and immunophenotype similar to that of GCT of bone. Primary giant cell tumor of soft tissue arising in the thyroid is exceedingly rare. Case presentation: We reported a new case of GCT-ST originating from the thyroid occurring in 69-year-old woman. Histologically, the tumor was composed of two morphological components, mononuclear cells admixed with multinucleated osteoclast-like giant cells. Tumor is devoid of atypia, pleomorphism, and atypical mitosis. Immunohistochemically, the tumor cells showed strongly positivity with antibodies to CD68, but were negative for AE1/AE3, EMA and additional muscle markers. Conclusions: Due to its rare occurrence, we analyzed the clinical features of patients with primary thyroid GCT-ST to summarize some of our experiences and conduct a literature. The interest of this case lies in the rarity of this entity, the difficulty in preoperative diagnosis, and the confusion with other malignancies.