Retroperitoneal neoplasms encompass tumors of different origins and nature (benign or malignant) that arise within this anatomical structure, but outside of the organs situated in the retroperitoneum [1] [2] [3] [4]. Some of the most important retroperitoneal neoplasms are [5] [6]:

• Lymphomas - Representing about 33% of all retroperitoneal malignant tumors, both non-Hodgkin and Hodgkin lymphomas may become apparent [3].
• Mesodermal tumors - Leiomyosarcoma, liposarcoma, and malignant fibrous histiocytoma comprise more than 80% of all sarcomatous tumors of the retroperitoneum [2] [5] [6]. Rhabdomyosarcomas, angiosarcomas, and chondrosarcomas are less common malignancies encountered in the retroperitoneum, together with fibromas, lipomas, and leiomyomas as their benign variants [2] [5].
• Neurogenic tumors - Schwannomas, ganglioneuromas, and neurofibromas are main benign lesions of the nervous tissue, whereas neurogenic sarcomas, neurofibrosarcomas, neuroblastoma and malignant schwannomas are notable malignant counterparts [3] [5].
• Sex cord tumors - About 1%-2.5% of gonadal tumors originate in extragonadal sites, and the peritoneum is one of them [3].

The clinical course of a retroperitoneal neoplasm is predominantly described as insidious, mainly because the tumor needs to grow considerably in size before producing symptoms [2] [4] [5]. Main complaints, when present, are abdominal pain, distension, and a palpable abdominal mass, while early satiety, abdominal swelling, and gastrointestinal/urinary symptoms, which were thought to be rare, are seen in up to 40-50% of cases [2] [3] [4] [5].

Because of a rather nonspecific (or even absent) clinical presentation, the diagnosis of a retroperitoneal neoplasm may be difficult to make. For this reason, the physician plays a crucial role when obtaining a detailed patient history and performing a thorough clinical examination. To identify the exact location of the tumor and determine its subtype, however, imaging studies need to be carried out. CT and MRI are the two main exams used in the assessment of the retroperitoneum [1] [3] [4] [5] [6]. Several findings that point to a retroperitoneal neoplasm are embedded organ sign (compression of the adjacent organ into a crescent shape), prominent feeding artery sign (hypervascularization of the presenting mass), and the presence of dull edges of the organ adjacent to the tumor [1]. Tumor types may be further discriminated by their distinguishing features:

• Liposarcoma - High signal intensity on T1-weighted studies, intermediate T2-weighted signal, and complete loss of fat signal intensity on MR images that suppress the fatty tissue [3].
• Leiomyosarcoma - Intermediate-to-low signal intensity on T1 and intermediate-to-high on T2 is typical, depending on the extent of necrosis [3].
• Malignant fibrous histiocytoma - A large-infiltrating and heterogeneous necrotic and hemorrhagic mass [3].
• Lymphoma - A well-defined homogeneous lump that mechanically compresses the major blood vessels [3].
• Schwannomas - Well-defined cystic masses with smooth margins [5].

The treatment of retroperitoneal neoplasms depends on several factors, including the type, size, and location of the tumor, as well as whether it is benign or malignant. Surgical removal is the primary treatment for most retroperitoneal tumors, especially if they are causing symptoms or are malignant. In some cases, additional treatments such as radiation therapy or chemotherapy may be recommended, particularly for malignant tumors that cannot be completely removed surgically.

The prognosis for patients with retroperitoneal neoplasms varies widely and depends on factors such as the type of tumor, its size, and whether it has spread to other parts of the body. Benign tumors generally have a good prognosis after surgical removal. However, malignant tumors can be more challenging to treat and may have a less favorable outlook, especially if they are diagnosed at a later stage.

The exact cause of retroperitoneal neoplasms is not well understood. Some factors that may contribute to their development include genetic mutations, exposure to certain chemicals or radiation, and a history of certain inherited conditions. However, in many cases, the specific cause remains unknown.

Retroperitoneal neoplasms are relatively rare, accounting for a small percentage of all tumors. They can occur in individuals of any age but are more commonly diagnosed in adults. There is no significant gender predilection, and the incidence does not appear to be influenced by race or ethnicity.

The pathophysiology of retroperitoneal neoplasms involves the abnormal growth of cells in the retroperitoneal space. These cells can originate from various tissues, leading to different types of tumors. Malignant neoplasms may invade surrounding tissues and spread to other parts of the body, a process known as metastasis, which complicates treatment and affects prognosis.

There are no specific measures to prevent retroperitoneal neoplasms due to the unclear etiology. However, maintaining a healthy lifestyle, avoiding exposure to known carcinogens, and undergoing regular medical check-ups may help in early detection and management of potential health issues.

Retroperitoneal neoplasms are rare tumors that occur in the retroperitoneal space of the abdomen. They can be benign or malignant and often present with non-specific symptoms, making diagnosis challenging. Treatment typically involves surgical removal, with additional therapies for malignant cases. The prognosis varies based on several factors, including the type and stage of the tumor.

If you or someone you know is experiencing symptoms such as persistent abdominal pain, a noticeable mass in the abdomen, or unexplained weight loss, it is important to seek medical evaluation. Retroperitoneal neoplasms are rare, but early diagnosis and treatment can significantly impact outcomes. Your healthcare provider can guide you through the necessary diagnostic tests and discuss potential treatment options based on the specific characteristics of the tumor.

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