Introduction: Ectopic thymoma is a rare neoplasm, which can be developed in various sites, with the lung being amongst the rarest.
Case presentation: In this paper, we present the case of a woman with a slow-growing ectopic thymoma, stemming from the visceral pleura of the upper lobe of the left lung anteriorly, extending into the left lung and the cardiac wall, invading the fatty tissue near the pericardium, notably without infiltrating the lung or cardiac parenchyma. The thymoma was successfully removed via thoracotomy.
Conclusion: Ectopic thymoma is an uncommon neoplasm. To our knowledge, a case of an ectopic thymoma stemming from the visceral pleura of the lung is extremely rare.