ALK-negative inflammatory myofibroblastic tumor with an undetermined differentiation direction: A case report and review of the literature.

[RATIONALE] Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal neoplasm that can arise in various anatomical locations, while IMT originating from the broad ligament is exceptionally rare. Anaplastic lymphoma kinase (ALK) is a highly specific diagnostic biomarker for IMT. However, no standardized therapeutic algorithm has been established for ALK-negative IMT, largely due to the unclear risk of distant metastasis and recurrence. In cases with undefined tumor differentiation and no detectable molecular targets, close surveillance and individualized therapeutic strategies should be guided by the tumor's biological behavior and patient-specific risk factors.

[PATIENT CONCERNS] We present the case of a 21-year-old unmarried, nulliparous woman who reported a palpable abdominal mass, ultimately found to originate from the broad ligament.

[DIAGNOSES] Exploratory laparotomy revealed a mass arising from the posterior leaf of the broad ligament along the posterior uterine wall. Histopathological analysis favored a diagnosis of ALK-negative IMT, although the origin and differentiation trajectory of the tumor remained undetermined.

[INTERVENTIONS] The patient did not undergo any adjuvant therapy, such as chemotherapy. Instead, a regimen of routine follow-up was implemented to monitor for disease progression or recurrence.

[OUTCOMES] At the 10-month follow-up, no clinical or radiological signs of recurrence or malignant transformation were observed.

[LESSONS] To date, surgical resection remains the mainstay of treatment for IMT. For ALK-negative IMT cases, molecular profiling to identify targetable genomic alterations may assist in selecting individualized targeted therapies.