Abstract
Inflammatory myofibroblastic tumor (IMT) is an intermediate-grade neoplasm of myofibroblastic
lineage occurring due to a cytogenetic clonal abnormality of chromosome 2p23. Pediatric
renal IMTs are rare and infant renal IMTs are almost anecdotal. We herein report a
1-year-old female child who presented with a firm mass in the right lumbar region.
Biopsy, and later, surgical resection revealed a tumor composed of spindle cells with
intermixed plasma cells. On immunohistochemistry (IHC), the lesional cells were positive
for smooth muscle actin and anaplastic lymphoma kinase (ALK). A diagnosis of IMT was
made based on morphology and IHC. Diagnosis of renal IMTs become challenging especially
in a tiny biopsy wherein clear cell sarcoma of kidney, Wilms tumor with predominant
mesenchymal component, congenital mesoblastic nephroma, and metanephric stromal tumor
are the differential diagnoses in this age group. Renal IMTs generally have better
prognosis as compared to extrarenal IMTs. Approximately, 50 to 60% of these tumors
harbor ALK gene rearrangement as demonstrated by positivity for ALK IHC. ALK inhibitors like crizotinib or ceritinib can be given for advanced metastatic tumors.
Keywords
inflammatory myofibroblastic tumor - kidney - ALK inhibitors
