Mucoepidermoid carcinoma of the thymus: a case report and review of literature.

backgroundMucoepidermoid carcinoma (MEC) is a predominantly salivary gland malignancy and an exceedingly rare primary thymic carcinoma, representing 1–2% of thymic carcinoma cases [1, 2]. Occurrence in the anterior mediastinum poses unique diagnostic and therapeutic challenges with surgical resection remaining the sole definitive treatment. The following case report highlights thymic MEC’s clinical, radiographic, and immunohistologic features, emphasizing the diagnostic workup, management strategies, and therapeutic outcomes for this rare tumor. CASE PRESENTATION: A 27-year-old obese female with polycystic ovary syndrome, and a family history notable for oculopharyngeal muscular dystrophy presented with a two-month history of dysphagia to solids and liquids accompanied by subjective pharyngitis. Physical examination was unremarkable, with no signs of muscular weakness or lymphadenopathy. Computed tomography (CT) of the neck revealed a prominent and heterogeneous anterior mediastinal mass, with further study of the chest confirming a 2.4 cm upper mediastinal mass adjacent to the thymic gland without hilar or mediastinal lymphadenopathy. An attempted CT-guided biopsy was complicated by pericardial tamponade requiring emergent pericardiocentesis. Pathologic evaluation of the limited biopsy was inconclusive, prompting surgical intervention. The patient underwent a right robotic thymectomy, achieving complete resection of the mass. Final pathology revealed immunohistopathologic findings consistent with a low-grade MEC with cystic changes. DISCUSSION AND

conclusionsMEC accounts for up to 30% of salivary gland malignancies, with the parotid gland representing the most common site. Thymic MEC remains exceptionally rare, with approximately 30 cases reported in the literature. These tumors can mimic more common anterior mediastinal masses such as thymomas or germ cell tumors, necessitating immunohistological confirmation for accurate diagnosis. This case underscores the diagnostic and therapeutic challenges of thymic MEC. Initial complaints of dysphagia are atypical in thymic masses. Complications during biopsy delayed diagnosis, however robotic-assisted thymectomy enabled precise and minimally invasive resection with expeditious recovery. This report contributes to the limited literature on thymic MEC and highlights the importance of multidisciplinary collaboration in managing rare mediastinal tumors. With mild cytologic atypia and no mitotic activity, this case suggests a favorable prognosis, reinforcing surgical resection as the cornerstone of treatment.