Incidental Rectus Abdominis Leiomyoma Discovered During Emergency Cesarean Section: A Rare Case Report From Northern...

Uterine fibroids, also referred to as leiomyomas, are benign uterine tumors with a lifetime prevalence of approximately 75% depending on race, age, and a variety of genetic and environmental factors. Extra-uterine leiomyomas are uncommon, and their occurrence within the rectus abdominis muscle is exceptionally rare. We present a rare case of an incidental rectus abdominis leiomyoma discovered during emergency cesarean section. A 28-year-old female (G3P1 + 1, living 1) presented to our specialty hospital in Northern Tanzania at 38 weeks and 1 day of gestation with complaints of lower abdominal pain for 8 h prior to admission. She had a previous cesarean section for breech presentation and one spontaneous abortion. On examination, she was in active labor with a 3 cm dilated cervix. Due to inadequate progression of labor, an emergency cesarean section was performed under spinal anesthesia. A live male infant weighing 3.3 kg was delivered with Apgar scores of 9 and 10 at 1 and 5 min, respectively. During the procedure, a 10 × 6 cm, well-circumscribed, firm, lobulated, reddish to dark-brown mass was incidentally identified embedded within the rectus abdominis muscle fibers. The lesion was completely separate from the uterus with no anatomical continuity and showed no evidence of local invasion. The mass was meticulously dissected and completely excised with adequate hemostasis. Histopathological examination revealed a well-circumscribed, noncapsulated benign smooth muscle neoplasm. Histologically, the lesion was composed of diffuse, uniform spindle cells with abundant eosinophilic cytoplasm and blunt-ended ("cigar-shaped") nuclei. There was no significant nuclear pleomorphism, mitotic activity, or necrosis. Immunohistochemical analysis demonstrated strong positivity for smooth muscle actin (SMA) in the tumor cells. Overall, the findings are consistent with a diagnosis of leiomyoma. The postoperative period was uneventful. The patient received standard analgesia and antibiotics and was discharged on postoperative day 4. At three-month follow-up, clinical examination and an abdominal ultrasound showed no recurrence of the mass, and the wound was healed.