Giant Retroperitoneal Angioleiomyoma, Case report and brief literature review

Angioleiomyoma (ALM), or vascular leiomyoma, is a rare, benign soft tissue tumor originating from the smooth muscle of vessel walls (tunica media). Retroperitoneal ALM is an exceptionally uncommon presentation, often creating substantial preoperative diagnostic uncertainty due to non-specific imaging findings that may overlap with malignant mesenchymal tumors. We report the case of a 45-year-old woman who presented with longstanding progressive abdominal distension, dull abdominal and lower back pain, early satiety, intermittent nausea, and exertional dyspnea. Cross-sectional imaging revealed a giant, well-defined, heterogeneous retroperitoneal mass measuring 17 × 12 cm, characterized by internal myxoid changes and prominent vascularity, which displaced the adjacent viscera without clear invasion. Because malignancy could not be excluded radiologically, a multidisciplinary tumor board reviewed the case, and a CT-guided core biopsy was performed to improve preoperative characterization and operative planning.
Exploratory laparotomy revealed a pedunculated retroperitoneal tumor attached by a fibrovascular pedicle, allowing complete en bloc excision with negative margins. Histopathology showed bland spindle smooth muscle cells surrounding thick-walled vascular channels, without atypia, necrosis, or mitotic activity. At the same time, immunohistochemistry (IHC) was positive for SMA, desmin, and h-caldesmon, confirming the diagnosis of retroperitoneal ALM. The postoperative course was uneventful, and no recurrence was detected at 12 months. This case highlights the diagnostic challenge, operative considerations, and favorable outcome associated with the complete resection of this rare benign retroperitoneal tumor.