Uterine Inflammatory Myofibroblastic Tumor with ALK Polysomy: Challenging Case Report and Review of Literature

Abstract

Abstract Introduction/Objective Inflammatory myofibroblastic tumor (IMT) is a distinct neoplastic process with specific molecular alterations. Given its low likelihood of local recurrence and metastasis, it is currently regarded as a neoplasm with intermediate biological potential. IMTs of the uterus variably express CD10 and smooth muscle markers, which present a diagnostic challenge and make it difficult to distinguish from mesenchymal neoplasms of smooth muscle and endometrial stromal origin. Methods/Case Report We present a case of a 46-year-old woman who underwent a hysterectomy due to abnormal menstrual bleeding. Grossly, a 5.0 cm tan, firm, well-circumscribed subendometrial nodule was identified at the fundus, which had a fleshy, soft-cut surface with no hemorrhage or necrosis. Microscopically, the nodule is composed of somewhat tightly packed spindle cells arranged in a fascicular pattern, with little-to-no myxoid stroma and dense lymphoplasmacytic infiltrate forming scattered aggregates. Immunohistochemical stains show lesional spindle cells are positive for SMA, desmin, and vimentin with patchy staining for ER while negative for S100, CD10, ALK-1, STAT6, and CD34. CD68 highlights scattered histiocytes in the background. Ki-67 highlights background lymphoid cells. RNA next-generation sequencing detected no fusions involving ROS1, PDGFR-β, or ETV6, which were previously described in a subset of ALK-negative IMTs. The FISH assay did not reveal rearrangements of the ALK or ROS1. However, extra intact ALK fusion signals were observed, suggesting polysomy for the ALK region. Results (if a Case Study enter NA) NA Conclusion To our knowledge, this is the first report of a uterine IMT with ALK polysomy. The significance of additional ALK copies in our case is not clear but highlights the need for further molecular studies investigating genetic alterations in ALK-negative IMTs. Detecting these rearrangements may be of diagnostic value and help guide future targeted therapies.