BACKGROUND Abdominal and retroperitoneal Castleman's disease could present either as a localized disease or as a systemic disease. Castleman's disease is a lymphoid hyperplasia related to human Herpes virus type 8, which could have an aggressive behavior, similar to that of malignant lymphoid neoplasm mainly with the systemic type, or a benign one in its localized form. METHODS The authors re...

Choriocarcinoma is a highly invasive and metastatic neoplasm which arises in women of reproductive age. It can be either gestational or nongestational in origin, but the latter form is very rare. Choriocarcinoma is characterized by the production of human chorionic gonadotropin. It can metastasize to distant organs such as lung, brain, liver, kidney, and vagina in the early stages of disease, b...

A 44-year-old man presented with cerebellar ataxia and limbic encephalitis and was ultimately diagnosed with metastatic germ cell neoplasm resulting from a "burned out" primary testicular tumor. The patient had progressive ataxia, leading to a thorough investigation for infectious, autoimmune, metabolic, and malignant causes of acquired cerebellar ataxia that revealed no significant findings. T...

Perivascular epithelioid cell tumor (PEComa) is an extremely rare neoplasm that appears to arise most commonly at visceral (especially gastrointestinal and uterine), retroperitoneal, and abdominopelvic sites. Malignant PEComas exist but are very rare. These tumors represent a family of mesenchymal neoplasms, mechanistically linked through activation of the mTOR signaling pathway. Metastatic PEC...

Primary retroperitoneal cavernous hemangioma (PRCH) in an adult is extremely rare. We report on the diagnosis and treatment of a patient with PRCH with subtle clinical features and atypical findings on imaging scans. A 38-year-old man was admitted to hospital with a 5-day history of epigastralgia after alcohol drinking. Using various imaging methods, we found a giant cyst-like retroperitoneal m...

For the first time extraskeletal osteosarcomas (ESOS) were described by Wilson in 1941. They are extremely rare neoplasms, presenting 4% of all osteosarcomas and 1,2% of all soft-tissue sarcomas. About 300 cases have been reported in the literature up to date. We present a 66-year-old female patient, admitted in the clinic because of acute bleeding in retroperitoneal space. Revision of the retr...

Testicular germ cell tumors, though rare (1%), represent the most common neoplasm among young men. Gastrointestinal involvement from these malignancies usually presents as bowel obstruction and digestive bleeding, but their frequency is low (5%). The patterns of this involvement are: infiltration from affected retroperitoneal lymph nodes or, less frequently, by peritoneal seeding and direct hem...

Pheochromocytoma is a rare and usually benign neuroendocrine neoplasm. Only 10% of all these tumors are malignant and there are no definitive histological or cytological criteria of malignancy. Single malignancy criteria are the presence of advanced locoregional disease or metastases. We report a case, with a giant retroperitoneal tumor having multiple metastases including palpable rib metastas...

Chondrosarcoma is an uncommon malignant neoplasm of cartilaginous origin. Extraskeletal chondrosarcomas are far less common than their intraosseous counterparts, representing approximately 2% of all soft tissue sarcomas. Clinically, extraskeletal mesenchymal chondrosarcoma (EMC) shows a very fast progression. It also has a high incidence of local recurrence and distant metastasis. The most comm...