Epithelioid inflammatory myofibroblastic sarcoma – A rare case report

Inflammatory myofibroblastic tumors are mesenchymal neoplasms made up of spindle cells with inflammatory infiltrates and are intermediate-grade tumors. Inflammatory Myofibroblastic Tumor (IMT) has a variant known as Epithelioid Inflammatory Myofibroblastic Sarcoma (EIMS) with aggressive behavior. Morphologically they have round to epitheliod cells that are positive for the Anaplastic Lymphoma Kinase (ALK) receptor tyrosine kinase. The abdomen and pelvis are the most common sites of involvement. Children and young adults are frequently affected. We report a rare case of EIMS arising on the serosal aspect of the ileocaecal junction in a 33-year-old male patient. Morphologically there were sheets and loose fascicles of epithelioid cells admixed with inflammatory cells in a variably myxoid background. Tumor cells were positive for Vimentin, Desmin, CD30, and Smooth muscle actin and showed cytoplasmic and nuclear membrane ALK positivity. Molecular studies in our case showed rearrangement of ALK by Vysis LSI ALK dual color break apart FISH probe. To our knowledge, this is the fifty-ninth reported case to date. Our case report highlights the clinical, histopathological, and immunohistochemical features of EIMS. Given their rarity and novelty, increased understanding and correct identification of the histological and immunohistochemical features of EIMS can result in an accurate diagnosis and focused treatment.