Unravelling the Enigma of Inflammatory Myofibroblastic Tumours: A Cross-sectional Study from a Regional Cancer Centre, Karnataka, India

Abstract

Introduction: Inflammatory Myofibroblastic Tumour (IMT) is an unusual neoplasm with intermediate malignant potential, which rarely metastasises. IMT occurs in various anatomical sites, and the initial descriptions were primarily centered on its manifestation in the lungs. Although the age range is broad, IMT is most common in the first three decades of life, with a slight female predominance. Recent data and Anaplastic Lymphoma Kinase (ALK) gene aberrations confirm a neoplastic process for these lesions. Aim: To study the clinicopathological features of IMTs in a regional cancer centre in South India. Materials and Methods: A cross-sectional study included 17 cases of IMT over six years, from May 2014 to May 2020, at Memorial Kidwai Memorial Institute of Oncology (KMIO), Bengaluru, Karnataka, India. The clinicopathologic and immunophenotypic features were analysed on needle biopsies and resected specimens. Correlation between the expression of ALK-1 and histological patterns, mimickers, metastasis, and prognosis were described. Results were analysed using Microsoft Excel 2019 and Medcalc calculator. Results: Seventeen cases of IMTs were included in this study, out of which two were in the lung, and the rest were extrapulmonary. Sixteen cases were unifocal on presentation; however, one IMT of extremity showed evidence of secondaries on bone scan. The mean age at presentation was 33.47 years, and the maleto-female ratio was 1:1.12. Among the seventeen cases, sites are as follows: one each in the retroperitoneum, liver, soft-tissue (extremity), two each in the breast, lung, female genital tract, urinary bladder, and three each in the head and neck region (maxilla, trachea, and alveolus) and mesentery. Microscopically, IMTs showed various histological patterns. Immunostaining for ALK-1 was positive in seven out of seventeen cases, and the rest were diagnosed by excluding closer mimickers. Conclusion: The present study provides crucial insights into the clinicopathological features of IMTs. Immunohistochemistry (IHC) is an essential diagnostic tool that helps accurately differentiate IMT from its mimickers by identifying ALK protein expression. This distinction is essential for guiding targeted therapy in recurrent or metastatic cases.