Spindle epithelial tumor with thymus-like differentiation involving the parathyroid gland: A case report with literature review

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare benign lesion characterized by the presence of spindle and epithelioid cells and features resembling thymic tissue. A 35-year-old asymptomatic female with a history of two cesarean sections and a positive family history of breast cancer underwent a thyroid checkup. Clinical examination revealed a normal thyroid gland, while diagnostic tests indicated a solid hypoechoic nodule in the right lower parathyroid gland, which was confirmed as SETTLE after surgical resection was performed, leading to an uneventful postoperative period. The patient, discharged on the first postoperative day, underwent comprehensive follow-up and oncology referral for risk stratification. In the literature review of nine cases of SETTLE (seven male, two female), age (8–70 years), past medical and surgical history of the majority is not available, most of them presented with painless and slowly enlarging mass in the neck, on laboratory examination most of the cases had test results within the normal range, ultrasound (U/S) and computed tomography (CT) Scan are preferred imaging modality, most of the patient had undergone surgical resection, histopathological examination showed SETTLE after management more than half were disease free. SETTLE is a rare tumor with ∼50 reported cases worldwide and a single case report that involves parathyroid glands. It can be asymptomatic or present as a mass. Besides the necessity of surgical resection, long-term follow-up is mandatory.