Uterine leiomyoma-like inflammatory myofibroblastic tumor: two case reports and literature review

Inflammatory myofibroblastic tumor (IMT) of the uterus is a rare low-grade malignant mesenchymal tumor characterized by its potential for recurrence and metastasis. The compact fibrous subtype can be easily misdiagnosed as a leiomyoma when it lacks a prominent inflammatory cell infiltrate. To enhance understanding of this disease and improve diagnostic vigilance, we present two cases of IMT exhibiting morphological features similar to leiomyomas for analysis. The ages of the two patients were 26 and 34 years, respectively. In Case 1, microscopic examination revealed densely packed spindle-shaped cells arranged in intersecting fascicles, with scattered inflammatory cells in the background and without myxoid stroma. The morphology closely resembled that of a leiomyoma, with only focal invasive growth. Case 2 involved a pregnant woman with a tumor that exhibited well-defined boundaries, varied cellularity, and compact regions with spindle cells arranged in bundles, along with stromal lymphocyte infiltration, while the loose areas demonstrated myxoid matrix. Immunohistochemical analysis indicated that both tumors were diffusely positive for ALK and expressed several myogenic markers. Fluorescence in situ hybridization (FISH) confirmed the presence of ALK gene breaks. A comprehensive understanding of these IMTs with leiomyoma-like features and accurate diagnosis are essential for effective patient treatment and prognosis.