The most frequent tumoral condition of the uterus is represented by uterine myoma. The diagnosis, in most cases, is established by clinical examination and ultrasound scan. Nevertheless, there are rare cases, in which the surgical findings reveal a retroperitoneal tumor instead of a uterine myoma. These could be represented by schwannomas or Castleman disease. The schwannomas are rarely malignant and arise from the Schwann cells of nerve fibers. These tumors are frequently found at the level of the head, neck and mediastinum and rarely in the pelvis. Generally, schwannomas localized at retroperitoneal level are asymptomatic and with a very slow growth rate. The treatment consists in complete surgical resection. The recurrence rate is low and, generally, the prognosis is good. The Castleman disease is considered a rare entity, but it should be always taken into consideration when it comes to a differential diagnosis in a young patient who presents a retroperitoneal mass at imagery exams. The condition affects the lymphatic system and is characterized by a hyperplasia of the lymph nodes, sometimes associated with herpes virus infection. The clinical picture is often non-specific; the pain may be the only symptom. The imaging methods are not always conclusive for the final positive diagnosis and the histopathological examination is always necessary. Pelvic Castleman disease can be misdiagnosed as myoma or an adnexal tumor. In this article, we review the present knowledge regarding the pathogenesis, pathology and management of these rare retroperitoneal tumors. Both conditions, when located in pelvis must be taken into consideration in the differential diagnosis of uterine myomas, especially in the pedunculated form.