ABSTRACT Inflammatory myofibroblastic tumours (IMT) are rare mesenchymal neoplasms that account for less than 1% of all lung tumours. Although ~50%–60% of IMT cases are anaplastic lymphoma kinase (ALK)‐positive, ALK‐negative IMT cases present diagnostic challenges owing to diverse pathological features. Here, we report a rare case of a rapidly growing ALK‐negative, neurotrophic tyrosine receptor kinase 3 (NTRK3)‐positive pulmonary IMT in a 46‐year‐old man with a history of pulmonary tuberculosis. A 13‐mm nodule detected during routine screening grew to 18 mm within 1 month. Complete surgical resection was performed by video‐assisted thoracic surgery. Histopathological examination revealed spindle cell proliferation with inflammatory cell infiltration. Immunohistochemistry was negative for ALK; however, molecular analysis identified an ETV6‐NTRK3 fusion gene. The patient remains disease‐free at 9 months postoperatively. This case highlights the importance of comprehensive molecular testing in ALK‐negative IMT and demonstrates that complete surgical resection can achieve excellent outcomes even in rapidly growing lesions.
Satō et al. (Mon,) studied this question.