Pitfalls in oncology: a unique case of thoracic splenosis mimicking malignancy in a patient with resected breast cancer

Thoracic splenosis (TS) is a condition of autotransplantation of splenic tissue into the pleural cavity after thoraco-abdominal trauma, with diaphragmatic and spleen injury. It is usually asymptomatic and discovered as an incidental finding at imaging performed for other reasons. Its differential diagnosis regards different benign and malignant conditions and should be discerned avoiding invasive procedures. We report a case of thoracic mass associated with pleural nodules mimicking malignancy in a patient with resected breast cancer for whom a diagnosis of TS was made early by using non-invasive methods. Briefly, we review the literature data on TS, comment concisely the possible implications of using invasive procedures and describe the current non-invasive techniques available. Furthermore, we highlight the importance of an accurate medical history collection, the role of the multidisciplinary board and their impact on treatment decision making. Finally, we conclude that clinical information and imaging would be the discriminating factors to avoid unnecessary invasive procedures.