Sinonasal Inflammatory Myofibroblastic Tumor with Anaplastic Lymphoma Kinase 1 Rearrangement: Case Study and Literature Review.

Inflammatory myofibroblastic tumors (IMTs) are rare mesenchymal tumors initially described in the lung. About half of them exhibit expression of the ALK1 protein, generally resulting from a gene rearrangement. Paranasal sinus IMTs are extremely uncommon, and gene rearrangement of ALK1 is very rare in this localization. A 47-year-old woman presented with rapidly progressive vision loss in her left eye. Clinical and imaging work-up revealed a tumor invading the left ethmoidal and sphenoidal sinuses and extending into the nasal cavity, the orbit and the skull base. Complete tumor resection was performed using an endonasal approach. Pathological examination revealed a paranasal localization of IMT, positive for ALK1 immunostaining. FISH analysis showed an ALK1 gene rearrangement. This case illustrates the local aggressive potential for IMTs. Treatment is primarily surgical, but targeted therapies (crizotinib) might be a solution for ALK1 rearranged cases with a poor prognosis.