Polypoid laryngeal inflammatory myofibroblastic tumors: misleading lesions: description of six cases showing ALK overexpression.

OBJECTIVES: Laryngeal inflammatory myofibroblastic tumors (IMTs) are rarely reported in the literature but may be underrecognized. To better characterize their features, we report a series of six cases.
METHODS: The clinicopathologic findings, including immunohistochemistry, fluorescence in situ hybridization (FISH) analysis, and follow-up, were evaluated and a review of the literature was performed.
RESULTS: These cases presented as small polypoid vocal cord or ventricular band lesions, with a more advanced mean age at diagnosis (49 years) than typically reported in other localizations. Apart from one secondary revision surgery, no complementary treatment and no recurrences were observed. Histologically, various morphologic features were seen. All tumors were spindle cell proliferations on a myxoid background with more or less atypia and significant inflammatory infiltrate. All six cases showed anaplastic lymphoma kinase (ALK) immunohistochemical expression. FISH rearrangement was present in four of six cases. Only two cases were initially diagnosed as IMT.
CONCLUSIONS: According to our series, laryngeal IMTs are easily misdiagnosed. They have a good prognosis, and ALK immunohistochemistry should be carried out to assess this diagnosis when spindle cell proliferations are observed in this localization. Copyright© by the American Society for Clinical Pathology.