Differential Diagnosis of Inflammatory Myofibroblastic Tumour and Low-grade Myofibroblastic Sarcoma: Two Case Reports with a Literature Review

Inflammatory myofibroblastic tumour (IMT) and low-grade myofibroblastic sarcoma (LGMS) have similar morphological and immunophenotypic features, but LGMS is more malignant than IMT and the treatment requires a wider surgical margin plus post-operative chemotherapy or radiotherapy. To date, only 28 cases of IMT and two cases of LGMS have been reported in the laryngopharynx. Recent studies have suggested that anaplastic lymphoma kinase (ALK) and cytokeratin are important markers for differentiating between the two tumours. Here, two cases involving different myofibroblastic tumours of the larynx are reported. Based on the histological and immunohistochemical results, case 1 was diagnosed as IMT involving the right arytenoepiglottic fold, while case 2 was diagnosed as LGMS involving the epiglottic-glossal surface. There was no recurrence or metastasis in either case after post-operative follow-up (12 and 14 months, respectively). It is difficult to distinguish IMT from LGMS; both morphological and immunohistological analyses are required.