A Case Report of Inflammatory Myofibroblastic Tumor Mimicking Leiomyosarcoma of the Uterus

Abstract Introduction/Objective Inflammatory myofibroblastic tumor (IMT) of the uterus is a rare entity that presents significant diagnostic challenges due to its infrequency and has the potential for being misdiagnosed as a leiomyoma, endometrial stromal tumor, or myxoid leiomyosarcoma, resulting in undertreatment or overtreatment. Methods/Case Report We present a case report of a 50-year-old woman with a history of anemia due to heavy menstruation caused by fibroids, who underwent hysterectomy. The concurrent pelvic wash cytology raised suspicious for myxoid leiomyosarcoma. Results (if a Case Study enter NA) Macroscopic examination revealed both well and poorly circumscribed nodules, ranging upto 4.7 cm in maximum dimension. Cut surfaces exhibited a spectrum of appearances, including tan-pink, whorled and rubbery, as well as soft, hemorrhagic, edematous, and mucinous areas with necrosis. Microscopically, the tumor exhibited myxoid spindle cell proliferation, in the background of lymphoplasmacytic inflammatory infiltrates. She was diagnosed with IMT metastasis to left fallopian tube, ovary, and omentum. Immunohistochemical (IHC) analysis further confirmed the diagnosis, showing strong and diffuse cytoplasmic positivity for ALK (anaplastic lymphoma kinase), caldesmon, and smooth muscle actin. This case underscores the critical importance of accurate diagnosis in guiding appropriate treatment strategies. Moreover, given the morphological overlap with other uterine tumors, the identification of ALK rearrangement emerges as a pivotal diagnostic marker, distinguishing IMT from its mimics such as leiomyoma, leiomyosarcoma and smooth muscle tumor of uncertain malignant potential (STUMP). Enhancing our understanding of the histomorphological features and ALK immunostaining of uterine IMT is essential for optimizing patient management and outcomes. Conclusion IMT in the female genital tract can mimic other more common benign and malignant tumors like leiomyoma, leiomyosarcoma, and endometrial stromal sarcoma. Familiarity with clinical and histologic features and the use of ALK immunostaining can be critical for correct diagnosis.