Rapidly growing pulmonary inflammatory myofibroblastic tumor: a case report

Inflammatory myofibroblastic tumor (IMT) of the lung is a rare mesenchymal tumor. Rapid growth of IMT is rare.

A 73-year-old woman was referred to our hospital because of a mediastinal tumor. Chest computed tomography (CT) showed a 13 mm anterior mediastinal tumor that was cystic on magnetic resonance imaging. A 6 month-follow-up chest CT revealed an 11 mm nodule in the left upper lobe of the lung. One month later, chest CT showed rapid growth of the lung nodule (diameter, 16 mm). The doubling time of the tumor was calculated as 19 days. Positron emission tomography revealed high accumulation of fluorodeoxyglucose in the nodule, which was suspected to be malignant. Robot-assisted thoracoscopic surgery was then performed. Intraoperative pathology of the left pulmonary tumor was poorly differentiated non-small cell carcinoma. Therefore, left upper lobectomy and resection of the anterior mediastinal tumor were performed. The final pathological diagnosis of the left pulmonary tumor was inflammatory myofibroblastic tumor; the mediastinal tumor was a thymic cyst. The patient's postoperative course was uneventful and she was discharged on postoperative day 4. She was recurrence-free at the 1-year follow-up.

IMT rarely presents with rapid growth and should be considered in the differential diagnosis of tumors with a doubling time <20 days.