A 53-year-old premenopausal woman was referred to our unit with a two-year history of progressive abdominal pain. The patient was nulliparous and had only benefited from umbilical hernioplasty 10 years ago. Physical examination found moderate pain of the abdomen with abdominal soft distension. No palpable mass was detected. Laboratory tests were normal. Abdomino-pelvic computed tomography (CT) and magnetic resonance imaging revealed massive infiltration of the lower parts of the abdomen by multiple enhancing solid and gelatinous lesions, covering all structures from the pelvis to the umbilic area without invading or compressing the intestine (Fig. 1), suggesting a benign form of pseudomyxoma peritonei such as peritoneal adenomucinosis. Thoracic CT found a similar 3-cm long cyst in the upper para-tracheal region. Colonoscopy was normal. Laparoscopic exploration was finally conducted and found, instead of classical puddles of mucin, multiple soft nodules of various sizes, massively infiltrating the great omentum, pelvis, pericolic gutters and the lower parts of the peritoneum, but preserving the small intestine (Fig. 2). Histopathology identified highly cellular interlacing bundles of smooth muscle cells, mimicking a leiomyosarcoma, although there were no nuclear atypia, mitotic figures, or signs of necrosis. Immunochemical analyses confirmed that the lesion was not malignant with a Ki67 ratio of 0%, intensively expressing desmin, caldesmon, estrogen, and progesterone receptors. A diagnosis of disseminated peritoneal leiomyomatosis was established. Because the disease was suspected to be metastatic and no signs of organic compression were noted, we decided to not perform surgical resection and proposed hormonal therapy using aromatase inhibitors. At one-year follow-up, the patient was fit and well, and imaging exams demonstrated stabilization of the disease.