Misleading Lesions in Gynecological Malignancies: A Case Report of Desmoid Tumor During Pregnancy and a Narrative Review of the Literature

Background: Desmoid tumors (DTs) are rare, locally aggressive soft-tissue neoplasms that often affect women of reproductive age. Pregnancy and prior abdominal surgery or trauma have been associated with tumor development and growth, while imaging frequently overlaps with abdominal-wall endometriosis. We present the case of a 39-year-old woman with an abdominal-wall DT and provide a narrative review of the literature focused on pregnancy/postpartum patterns, differential diagnosis, and management. Methods: A narrative review of PubMed/MEDLINE and Web of Science (January 1982–December 2024) was conducted. We included English-language case reports/series, narrative/descriptive reviews, and consensus statements relevant to DTs in pregnancy or reproductive-age women, emphasizing abdominal-wall disease. Results: The patient’s right abdominal-wall mass enlarged during pregnancy and further post-partum imaging repeatedly suggested endometriosis. En bloc resection revealed desmoid-type fibromatosis composed of bland spindle cells in a collagenous stroma, with nuclear β-catenin and lymphoid enhancer–binding factor 1 (LEF1) positivity on immunohistochemistry. Magnetic resonance imaging (MRI) at 12 months showed no recurrence. Across included studies, pregnancy and post-partum enlargement is common, abdominal-wall DTs frequently mimic scar endometriosis, and pre-operative ultrasound has limited specificity. Current practice supports watch-and-wait for stable, asymptomatic lesions and function-preserving surgery for symptomatic progression, while systemic options (anti-estrogens, low-dose chemotherapy, and tyrosine kinase inhibitors) are reserved for progressive or unresectable disease. Recurrence risk relates to age, size, site, and β-catenin status; future pregnancy is not contraindicated. Conclusions: Abdominal-wall DTs, although rare, should be considered in the differential diagnosis of reproductive-age women presenting with abdominal-wall masses, particularly during or after pregnancy.