Giant Extraluminal Leiomyoma of the Colon: Rare Cause of Symptomatic Pelvic Mass

Leiomyomas (LMs) may appear throughout the entire gastrointestinal tract but are rarely seen in the colon-rectum and only 5 of those measured greater than 15 cm in diameter. Pain and palpable abdominal mass are the most common symptoms. Surgical resection is the treatment of choice for most LMs. We here describe a case of a 46-year-old woman who presented with a 3-month history of abdominal pain associated with worsening constipation and abdominal distension. A pelvic solid, polylobulate, left-sided mass was noted on examination. Preoperative findings revealed a dishomogeneous sigmoid mass with calcified spots compressing small intestine and bladder. At laparotomy, a large polylobulate and well-circumscribed mass arising from the descending colon mesentery and displacing small intestine, uterus, and ovaries. A segmental colon resection was performed. An extraluminal 18- × 12- × 5-cm paucicellular sigmoid colon leiomyoma was histologically diagnosed. Our case is one of the few giant (>15 cm) sigmoid colon LMs reported in the literature. Although rare and benign in nature, LMs of the colon can cause life-threatening complications that could require emergency treatment and they should be included in the differential diagnosis of large abdominopelvic masses. Follow-up after surgery is necessary for tumors with any atypia or mitotic activity.Key words: Leiomyoma, Digestive tract, Bowel obstruction, Pelvic massPrimary leiomyomas (LMs) present most commonly in the female genital tract and skin but they are rarely seen in the colon-rectum. Macroscopically, LMs may be intraluminal, intramural, extramural, or dumbbell.^1,2 The majority of LMs remain asymptomatic until they have reached a large size: most common symptoms are pain and palpable abdominal mass.^1,2 Symptomatic left colon LMs are uncommon and only 5 of those reported in the literature measured greater than 15 cm in diameter.¹ Histologically, most of them arise from the muscularis propria.^1,3 The most important differential diagnoses are malignant leiomyosarcoma and gastrointestinal stromal tumors (GIST).^1,3 Surgical resection is the treatment of choice for large LMs: complete excision should be always attempted and follow up is necessary for tumors with any atypia or mitotic activity.^1,2 Although rare and benign in nature, LMs of the colon can cause life-threatening complications that require emergency treatment.^1–3 We here describe a case of large extraluminal sigmoid colon LM causing pain and worsening bowel obstruction.