Castleman’s disease (CD) was described from Benjamin Castleman in 1954. The disease today is enumerated among lymphoproliferative disorders and has unknown etiology, but a interleukin-6 (IL6) dysregulation and a reaction to viral antigens (HHV8) especially in patients with immunodeficiency is suspected. It is observed in adult and young people, in male or female with equal frequency; the appearance in childhood is extremely rare. The disease shows various clinical and histological pictures, with a localized type (involvement of one lymph node group) described more frequently than the multicentric one. Histological examination distinguish a “hyaline-vascular type” that represents approximately the 91%, a “plasma cell type” that represents approximately the 9% has an aggressive clinical outcome, and the “ mixed types”. Initial symptoms are nearly absent, but not for the plasma cell type. We describe the clinical case of a female patient 21 years old. She reached our observation in May 1999, referring us for pelvic pains and amenorrhoea from four years. During 1996 she underwent to a laparoscopy that diagnosed an endometrial cyst on left ovary. A year later a new retroperitoneal mass was discovered and a second laparoscopy was performed with a little partial excision of the tumor. In our Institute the us and the TC showed a retroperitoneal mass of 4,5 cm of diameter, next to the uterus and the iliac left vessels. The patient underwent surgical laparotomic excision and histological examination showed hyaline vascular type of CD. Three years after surgery the patient is still free of any symptoms.