Case Report: Synchronous ALK-positive laryngeal inflammatory myofibroblastic tumor and EGFR-mutant lung adenocarcinoma in a child.

The concurrent occurrence of two histogenetically distinct tumors in a child is exceptionally uncommon and may create substantial diagnostic uncertainty. To the best of our knowledge, this is the first reported case of synchronous diagnosis of an ALK-rearranged inflammatory myofibroblastic tumor (IMT) of the larynx and EGFR-mutant lung adenocarcinoma. A 7-year-old boy presented with dyspnea and hoarseness. A laryngeal mass was resected and confirmed to be ALK-positive IMT harboring a THBS1-ALK rearrangement. PET-CT also detected a solitary lung nodule in the right lower lobe, which was initially considered possible metastatic IMT. However, serial chest CT over 22 months demonstrated only minimal, indolent enlargement, a pattern that was inconsistent with the expected behavior of metastatic disease. Because of this clinicoradiologic discrepancy, thoracoscopic wedge resection was performed for definitive diagnosis. Histopathology revealed acinar-predominant invasive adenocarcinoma of the lung that was positive for TTF-1, and Napsin A, and negative for ALK. Next-generation sequencing identified an EGFR exon 20 insertion (p.N771_P772insG) and a low tumor mutational burden. The discordant clinical behavior, isolated and indolent radiologic evolution, divergent histopathologic and immunophenotypic profiles, and distinct oncogenic drivers collectively supported a diagnosis of synchronous primary tumors rather than metastatic IMT. Because sequencing was limited to the DICER1 hotspot region, other hereditary cancer-predisposition mechanisms could not be definitively excluded. This case underscores the importance of longitudinal imaging, integrated pathology, and molecular profiling when presumed metastatic disease follows an atypical course pediatric oncology.