Background/purpose: Inflammatory myofibroblastic tumor (IMT) is considered as an intermediate neoplasm that may present malignant features. Differential diagnosis with other tumor processes is sometimes difficult. Similar anaplastic lymphoma kinase (ALK) gene abnormalities as in anaplastic large cell lymphoma have been reported. Human herpesvirus 8 (HHV-8) DNA sequences have been described in adult pulmonary IMTs and Epstein-Barr virus (EBV) has been reported in splenic and hepatic IMTs, suggesting the importance of both viruses in IMT development. This article aims to evaluate ALK, EBV, and HHV-8 expression in children with IMT and to correlate our findings with clinical features.
Methods: Sixteen children (range, 1-15 years) who had surgery for IMT between 1978 and 2003 were evaluated retrospectively. Formalin-fixed, paraffin-embedded archival tissues were stained for HHV-8 and ALK with immunohistochemistry. Epstein-Barr virus was detected by in situ hybridization (EBER probes).
Results: Tumors were located in the pulmonary lobe (n = 4), urinary tract (n = 4), mesentery or bowel (n = 4), hepatic lobe (n = 1), vena cava (n = 1), spinal cord (n = 1), and soft tissue (n = 1). Five children were treated with steroids and/or antibiotics before surgery, with no substantial result. IMT was excised totally in all but 2 cases. Four patients presented aggressive IMT with recurrence or metastasis requiring new surgery. ALK was positive in 3 (18.8%) cases and EBV in 1 pulmonary and 1 bladder tumor, all of them without recurrence or metastasis. None of the cases were positive for HHV-8. All patients are now disease-free with a mean follow-up of 4.2 years.
Conclusions: Considering the present lack of efficient medical treatment, surgery should still be considered as the mainstay therapy in IMT, even in cases of recurrence or metastases. Larger multicentric studies would be necessary to understand the prognostic significance of ALK, EBV, and HHV-8 and their relationships with the origins of the tumor.