Inflammatory myofibroblastic tumor following hematopoietic stem cell transplantation: report of two pediatric cases.

Inflammatory myofibroblastic tumors are benign neoplasms histologically composed of lymphocytes, histiocytes, macrophages, foam cells, and plasma cells among a spindle-shaped stroma. Their etiology and potential for metastatic spread is controversial. Numerous predisposing factors have been suggested, including preceding infections, radiotherapy, and local trauma. We present two cases of pseudotumors that developed in children following hematopoietic stem cell transplantation. These are the first cases after hematopoietic transplant reported in the literature. As these neoplasms are difficult to diagnose and are often confused with highly aggressive tumors, our cases demonstrate that a high index of suspicion for such lesions must be maintained when evaluating masses in post transplant patients.