Thymolipomas are rare tumors of the anterior mediastinum containing both thymic stroma and an abundance of fat. We present a 40-year-old man with no underlying disease who presented with cough and progressive dyspnea. Clinical evaluation revealed a giant mass of lipid density filling almost the entire left hemithorax with mediastinal shift. Total excision of the 40 × 33 × 8 cm mass weighing 4 kg was performed via a left thoracotomy and the histopathologic diagnosis of the mass was reported as thymolipoma. The patient remains alive and disease-free, twelve months after the intervention.

HighlightsIn every patient diagnosed with a tumoral lesion, the possibility of a second primary tumor should be considered.Patients with thymoma are more likely to experience extrathymic neoplasms and the incidence of extrathymic cancers is increased both before and after the diagnosis of thymoma.Symptoms and signs unrelated to a diagnosed primary tumor should be carefully assessed for a possible concurrent neoplasm.Treatment decisions for a patient with double primary tumor should be individualised and the lesion with more life-threatening outcome should be treated first.Simultaneous operation for two primary malignant tumors in different anatomic regions is not generally recommended.