Abdominal wall endometriosis misdiagnosed as a desmoid tumor: A case report

INTRODUCTION: Abdominal wall masses have different aetiologies. Diagnosis includes desmoid tumors (DTs) and other benign and malignant lesions, among which abdominal wall endometriosis (AWE). Diagnosis is challenging if symptoms are aspecific, and the contribution of imaging may be weak. We present a case of AWE that according to clinical history and imaging was misdiagnosed as DT. PRESENTATION OF CASE: A healthy 35-year-old female presented, 4 years after a cesarean delivery, a rapidly growing painless subumbilical mass within the right rectus abdominis muscle. Ultrasound and magnetic resonance imaging suspected a DT. The patient underwent complete resection of the mass and pathological examination revealed foci of endometriosis in the muscle. Patient's post-operative course was uneventful and at 18-month follow-up, no recurrence has been detected. DISCUSSION: The current case highlights differences in clinical presentation and imaging in case of AWE and DTs, underlining possible pitfalls in diagnosis. In young women with previous gynaecological abdominal surgery, AWE is the most likely disease when a mass in the region of the scar appears. Differential diagnosis is complex and rare entities like DTs should nevertheless be taken into consideration. A complete surgical resection with negative margins is considered the primary treatment for AWE and for selected DTs. Final pathology of the tumor can state the precise diagnosis. CONCLUSION: Since AWE and DTs share similar clinical signs and aspecific imaging exams, both diseases should be considered in case of abdominal wall mass in female patients of childbearing age and history of uterine-related surgery.