ALK-Negative Inflammatory Myofibroblastic Tumor: A Challenging Case in a Premature Newborn

Inflammatory myofibroblastic tumors (IMT) are rare borderline tumors with a variable histological appearance that may mimic multiple mesenchymal tumors. We present a rare case of a challenging abdominal mass discovered in a premature newborn. The histopathology showed a bland myofibroblastic proliferation associated with an inflammatory infiltrate that was positive for smooth muscle actin and desmin but negative for anaplastic lymphoma kinase (ALK) protein. The diagnosis of an ALK-negative IMT was established. The tumor was partially resected. After six months of follow-up, the residual tumor remained stable, and the patient was asymptomatic. The correct diagnosis and subsequent treatment of ALK-negative IMT require appropriate histopathological, immunohistochemical, and sometimes genetic examination. Further research has to be conducted to help clinicians make an appropriate treatment plan.