Unusual Behavior of a Lung Inflammatory Myofibroblastic Tumor: Case Report

55 years old, male patient. History of heavy smoking (65 UMA) and COPD. Admitted to hospital due to a left pneumonia. Thoracic CT and PET-Scan, showed left lower lobe mass measuring 92x89 mm (SUVmax 49). Several mediastinal node groups presented increased uptake of FDG. A fiberoptic bronchoscopy was performed. Citology of the bronchoalveolar lavage suggested a squamous carcinoma. EBUS of node stations 4R, 4L e 7 without evidence of malignancy.

The case was taken to a multidisciplinary meeting staged as IIIA (T3N2M0). Neoadjuvant therapy (four cycles cysplatine and gemcitabine) was decided based on station 5, suspected disease. A left lower lobectomy was performed after a cervical mediastinoscopy excluded metastasis of node stations 4R and 4L. Histology of the specimen was compatible with inflammatory myofibroblastic tumor (IMT). No lymph node involvement was reported. It was restaged as IIB (ypT3N0M0).

Three months after surgery one de novo nodule in the lingula with 12,7 of SUVmax was reported. The nodule was removed confirming a IMT metastasis. Four months after the nodule ressection a CT showed new lung and liver nodules. A total oclusion of the left main bronchus was documented and bronchoscopic debulking of the endobronchial mass again revealed IMT. Paliative radiotherapy was decided in the multidisciplinar group targeting the left main bronchus (five sessions of radiotherapy on a dose of 20Gy in 4Gy daily fractions). Ten months after surgery due to the onset of back pain, a CT revealed a sacrum lesion whose needle biopsy was suspicious for multiple myeloma. The patient was referred to another oncological center where previous non-surgical cases had been sent in the past. The patient is now proposed for histology reassessment and discussion by the hematology and pneumology medical teams.

Inflammatory myofibrobastic tumors are considered benign or low-grade malignant tumors. The size of the tumour (cut-off of 3 cm) and secure surgical resection with free margins are the major determinants for recurrence and survival. There are some cases reported in the literature of distant metastasis and sarcomatous transformation after multiple recurrences. In our patient, the lesion was bigger than 3 cm and he underwent a complete resection. Nothing could foresee this aggressive metastatic behavior, especially when the recurrence did not show a sarcomatous transformation.