Retroperitoneal tumors are a group of malignant and benign neoplasms of mesodermal, neurogenic and embryogenic origin localized in the retroperitoneal space. Characterized by a long asymptomatic course. With large retroperitoneal tumors, dyspeptic disorders, urination disorders, shortness of breath, neurological symptoms and swelling of the lower extremities are observed. With malignant lesions in the late stages, signs of cancer intoxication are revealed. The diagnosis is made taking into account CT, MRI, ultrasound, biopsy and other studies. Treatment – surgery, radiotherapy, chemotherapy.
Extraorgan retroperitoneal tumors are a group of neoplasms originating from the tissues of the retroperitoneal space, including fat, muscle, connective and nervous tissue, lymph nodes, lymphatic and blood vessels and embryonic elements. The group of retroperitoneal tumors does not include oncological processes in organs located in this space, as well as metastatic lesions of retroperitoneal lymph nodes in tumors of other localizations. The reasons for combining such heterogeneous diseases into one group are similar features of the clinical course, common methods of diagnosis and therapy.
Retroperitoneal tumors can be both malignant and benign. They are rare, according to various data, they range from 0.03 to 0.3% of the total number of oncological diseases. Some experts believe that this figure is underestimated due to diagnostic difficulties in detecting this pathology. They are found mainly at the age of 50 years and older. Representatives of both sexes suffer equally often. The treatment is carried out by specialists in the field of oncology, neurology and vascular surgery.
Retroperitoneal space is the space between the posterior leaf of the peritoneum, the diaphragm, the muscles of the back, the spine and the muscles lining the bottom of the pelvis. In this anatomical zone, the pancreas, kidneys, adrenal glands, ureters, part of the duodenum and part of the large intestine are localized. The space between the organs is filled with fiber, in which the nerve plexuses, lymph nodes, lymphatic and blood vessels are located. Retroperitoneal fiber is divided by fascia into several sections.
Non-organ retroperitoneal tumors are considered to be any nodes located in this space, with the exception of neoplasms originating from the organs listed above, as well as metastatic lesions of lymph nodes and tumors sprouting into the retroperitoneal space from other anatomical zones (for example, from the abdominal cavity). The most popular classification of retroperitoneal tumors, created by Ackermann in 1954, is based on histogenetic features of neoplasias. According to this classification, there are three large subgroups of such neoplasms: mesodermal, neurogenic and originating from elements of embryonic tissues.
Mesodermal retroperitoneal tumors:
- Originating from adipose tissue: lipomas (benign) and liposarcomas (malignant).
- Originating from smooth muscle tissue: leiomyomas (benign) and leiomyosarcomas (malignant).
- Originating from striated muscle tissue: rhabdomyomas (benign) and rhabdomyosarcomas (malignant).
- Originating from connective tissue: fibroids (benign) and fibrosarcomas (malignant).
- Originating from blood vessels: hemangiomas (benign) and angiosarcomas (malignant), hemangiopericytomas (benign and malignant).
- Originating from lymphatic vessels: lymphangiomas (benign) and lymphangiosarcomas (malignant).
- Originating from the remains of the primary mesenchyme: myxomas (benign) and myxosarcomas (malignant).
- Unclear histogenesis: xanthogranulomas (benign).
Neurogenic retroperitoneal tumors:
- Originating from nerve membranes: neurofibromas (benign), neurolemomas (benign and malignant).
- Originating from sympathetic nerve ganglia: ganglioneuromas (benign) and ganglioneuroblastomas (malignant).
- Originating from chromaffin and non-chromaffin cells of the paraganglia and out-of-the-border areas of the adrenal tissue: paragangliomas (benign, malignant), pheochromocytomas, cancer from adrenal cells.
Retroperitoneal tumors from embryonic remains: teratomas, chordomas.
The causes of retroperitoneal tumors have not yet been clarified. Scientists identify a number of factors contributing to the development of this pathology. Such factors include specific and non-specific genetic disorders, exposure to ionizing radiation and certain chemicals. A possible connection with ionizing radiation is indicated by an increased likelihood of retroperitoneal tumors in patients who previously received radiotherapy during the treatment of other oncological diseases.
There are studies indicating an increased risk of developing certain types of neoplasms of this localization when exposed to herbicides and pesticides, especially dioxin and phenoxyacetonic acid derivatives. The mechanism of stimulation of retroperitoneal tumor growth in such cases has not yet been clarified. There are versions of both direct and indirect effects as a result of suppression of immunity under toxic chemical exposure.
A feature of retroperitoneal tumors is the prolonged absence of clinical symptoms due to the presence of a large amount of loose fiber and the relative mobility of neighboring organs. Some neoplasms reach huge sizes without causing disorders of the digestive and urinary system. In the literature there are descriptions of individual nodes weighing from 13 to 51 kg .
Another typical sign of retroperitoneal tumors is the absence of specific symptoms. The clinical picture of the disease is caused not by the type of neoplasm, but by its localization (in the lower, upper or lateral part of the retroperitoneal space), the proximity of certain organs and anatomical formations (blood vessels, nerves, lymphatic ducts). Patients with retroperitoneal tumors usually see a doctor for the first time due to constant abdominal pain. On palpation, 80% of patients have nodes of various sizes and consistencies. In half of the cases, the probing of the retroperitoneal tumor is accompanied by pain of varying intensity.
There may be complaints of nausea, vomiting, premature appearance of a feeling of satiety and stool disorders. With neoplasms localized in the lower part of the retroperitoneal space, urination disorders caused by compression of the bladder may occur. With highly located retroperitoneal tumors, shortness of breath sometimes develops due to pressure on the diaphragm. In the early stages, hypothermia and hyperhidrosis of the lower limb on the affected side are detected in many patients. In the later stages of the disease, hypothermia of the limb is replaced by hyperthermia. The development of this symptom in retroperitoneal tumors is due to initial irritation and subsequent paralysis of the sympathetic nerve.
With compression of large veins located in the retroperitoneal space, edema and varicose veins in the lower extremities are observed. Neurological disorders are detected in 25-30% of patients. With malignant retroperitoneal tumors in the late stages, weight loss, loss of appetite, fever of unknown genesis and general hyperthermia are noted. Neoplasms of this localization often recur, but rarely metastasize. Metastatic liver and lung damage is characteristic. Secondary tumors in the ovaries and lymph nodes are less common.
The diagnosis is established on the basis of complaints, the results of an external examination and additional studies. Patients with suspected retroperitoneal tumor are referred for ultrasound, CT and MRI of the abdominal cavity and retroperitoneal space. The listed diagnostic methods make it possible to determine the structure and localization of the neoplasm, assess the degree of involvement of nearby organs and identify distant liver metastases. Taking into account a number of signs (shape, density, presence or absence of a capsule, level of homogeneity, degree of vascularization), after ultrasound, MRI and CT, a specialist can assess the malignancy of a retroperitoneal tumor and make reasonable assumptions about the type of neoplasm.
To assess the state of the digestive and urinary system, X-ray contrast methods (irrigoscopy and excretory urography) are used. To identify germinogenic neoplasms, tests are prescribed to determine alpha-fetoprotein and chorionic gonadotropin. Since the main method of treatment of retroperitoneal tumors is their radical removal, a biopsy is usually not performed due to the high risk of contamination and insufficient expediency of the study. The exception is situations when the material is taken for the purpose of planning an operation, determining the resectability of a neoplasm or excluding the metastatic nature of an oncological lesion.
The only radical way of treatment is surgical intervention. Depending on the localization, retroperitoneal tumor removal is performed using lateral access, median laparotomy or thoracoabdominal access. In more than half of the patients, the operation involves resection of nearby organs: kidney, pancreas, duodenum or colon. The effectiveness of pre- and postoperative radiotherapy and chemotherapy for retroperitoneal tumors remains in doubt. The indication for the use of these therapeutic techniques is the proven malignancy of the neoplasm in the presence of doubts about its operability.
Data on the operability of retroperitoneal tumors vary greatly. In the literature there are indications of both 25% and 95% resectability of such neoplasms. Postoperative mortality in the removal of retroperitoneal tumors is about 5%, the probability of developing local relapses in the long term is about 50%. Less than 10% of patients suffering from malignant neoplasms survive up to 5 years from the moment of surgery. With benign retroperitoneal tumors, the prognosis is more favorable, however, the high probability of recurrence causes the need for a large number of repeated surgical interventions.