PRIMARY DISEASES OF THE PERITONEUM
Sommaire
Peritoneal pseudomyxoma
Gelatinous disease of the peritoneum is characterized by disseminated mucinous tumors of the peritoneum and mucinous ascites of the abdomen and pelvis.
Synonyms:
Gelatinous ascites, Gelatinous disease of the peritoneum
Epidemiology:
The estimated annual incidence is approximately 2 new cases per 1,000,000, with a predominance in women. The diagnosis is usually made after the age of 40.
Clinical description:
In 30 to 50% of cases, the disease manifests as progressive abdominal distension (or “gelatinous abdomen”). The discovery of an ovarian mass or the recent onset of an inguinal hernia, appendicitis, or intestinal obstruction may lead to diagnosis. Abdominal pain, weight loss, urinary symptoms, constipation, vomiting, or dyspnea are less common clinical signs.
Etiology:
In 90% of cases, the primary lesion (causing the disease) is a mucinous appendicular tumor (mucinous tumors of the ovary have been reported in 7% of cases, and more rarely of the colon, stomach, pancreas, and urachus).
Diagnostic method:
The diagnosis is based on a thoracoabdominal pelvic CT scan (which reveals the characteristic compartmentalized distribution of gelatinous ascites) and on pathological examination (performed by two experts); tumor marker testing (carcinoembryonic antigen and CA 19-9) is less specific. Abdominal MRI improves the assessment of the disease.
Differential Diagnosis:
The differential diagnosis must rule out secondary peritoneal carcinomatosis and other rare tumors of the peritoneum.
Treatment:
Treatment is multidisciplinary and must be carried out in a specialist center (RENAPE network): The best curative option is complete cytoreductive surgery (visceral resection and peritonectomy) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), sometimes followed by intravenous chemotherapy, a therapeutic protocol that can only be considered for young patients in good general health. Chemotherapy is used for high-grade forms, after surgery or in the event of recurrence
Prognosis:
Gelatinous peritoneal disease progresses slowly and recurrence after total tumor removal remains possible. After combined treatment (complete cytoreductive surgery and IPIC) of non-aggressive peritoneal pseudomyxoma, the survival rate reaches 70% at 20 years for patients treated by a specialist center.
AMARAPE Scientific Advisory Board chaired by Professor Olivier Glehen (February 2025)
Malignant peritoneal mesothelioma
Malignant peritoneal mesothelioma (MPM) is a primary malignant tumor of the parietal cells (mesothelium) of the peritoneal cavity. Peritoneal mesothelioma accounts for 10 to 30% of malignant mesotheliomas, with the remaining cases mainly affecting the pleura.
Synonyms:
Primary malignant mesothelioma, diffuse malignant peritoneal mesothelioma
Epidemiology:
The annual incidence is approximately 1/500,000 in France, but reaches 1/200,000 in certain regions of Europe (Italy). The disease predominantly affects men. The diagnosis is usually made in middle-aged adults (median age: 55 years).
Clinical description:
The typical initial clinical signs are abdominal distension, abdominal pain, the presence of an abdominal mass, a deterioration in general health, weight loss, and ascites. Dyspnea, coagulation disorders, edema of the lower limbs, and intestinal obstruction may also be observed.
Etiology:
The relationship between peritoneal mesothelioma and asbestos exposure is unclear, particularly in women, and has not been established as it has been in pleural mesothelioma. Other agents have been reported, such as exposure to erionite, viral infections, and vaccine products and/or genetic susceptibility.
Diagnostic method:
The diagnosis is based on imaging tests, such as ultrasound and thoracoabdominal-pelvic CT scan. The diagnosis is confirmed by pathological examination of a biopsy obtained by laparoscopy, appropriate immunostaining of the biopsy sample (positive for calretinin and negative for ACE), and must be reviewed by two experts (MESOPATH network).
Differential diagnosis:
Differential diagnoses include peritoneal carcinomatosis secondary to colorectal or gastric cancer and primary peritoneal carcinoma.
Treatment:
Treatment is multidisciplinary and must be carried out in a specialist center (RENAPE network). Curative treatment is based on cytoreductive surgery (visceral resections and peritonectomies) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) in certain patients (young, in good condition, with a suitable tumor volume). Systemic chemotherapy with Alimta (disodium pemetrexed) and cisplatin may be used as palliative treatment, or intraperitoneal chemotherapy, with or without PIPAC. Immunotherapy may also be beneficial.
Prognosis:
With palliative treatment (systemic chemotherapy), median survival is less than 1 to 2 years. After cytoreductive surgery and HIPC, median survival can reach more than 50 months with a 5-year survival rate of more than 50%.
AMARAPE Scientific Council chaired by Professor Olivier Glehen (February 2025)
Peritoneal inclusion cysts or formerly cystic mesothelioma of the peritoneum
Peritoneal inclusion cysts are a rare benign tumor characterized by the formation of intra-abdominal multilocular cystic masses.
Synonyms:
Multilocular peritoneal inclusion cyst, multicystic mesothelioma, benign multicystic peritoneal mesothelioma.
Epidemiology:
Fewer than 150 cases have been reported to date. It occurs more frequently in women of childbearing age.
Clinical description:
Symptoms include lower abdominal or pelvic pain, the presence of a palpable mass, amenorrhea, dysuria, dyspareunia, and in some cases, incidental discovery.
Etiology:
The masses are usually located on the peritoneal surface of the uterus and rectum in women, and on the bladder and rectum in men. Dissemination can reach the upper parts of the peritoneal cavity, the omentum. The inclusion cyst appears to originate from the peritoneal mesothelium. However, its etiology is unknown. There is no relationship with asbestos exposure. It frequently occurs in women with a history of pelvic surgery or inflammation, or endometriosis. Chronic peritoneal irritation may be an aggravating factor.
Diagnostic method:
The diagnosis is based on abdominal-pelvic ultrasound, abdominal CT scan, and laparoscopy showing multi-cystic formations divided into clusters resembling bunches of grapes. Biopsy shows cysts filled with translucent fluid, with thin walls, vascularized and composed of loose connective tissue. Immunohistochemistry confirms the diagnosis by showing the mesothelial origin of the parietal cells (this test must be performed by expert pathologists – MESOPATH network).
Differential diagnosis:
The main differential diagnoses are cystic lymphangioma of the peritoneum, gelatinous disease of the peritoneum, and other cystic neoplastic lesions.
Treatment:
The treatment regimen must be established within an expert center (RENAPE network). Treatment is surgical and involves the removal of cysts to confirm the diagnosis. In the event of recurrence or as a first-line treatment, cytoreductive surgery combined with hypothermic intraperitoneal chemotherapy (HIPEC) may be considered in certain patients (young and in good general health).
Prognosis:
The prognosis is usually good. All patients treated with the combined protocol are alive at 5 years. The recurrence rate is high, but invasive or malignant progression is extremely rare.
AMARAPE Scientific Advisory Board chaired by Professor Olivier Glehen (February 2025)
Disseminated peritoneal leiomyomatosis
Disseminated peritoneal leiomyomatosis (DPLM) is characterized by the proliferation of multiple benign smooth muscle cell nodules in the peritoneal cavity.
Synonyms:
Diffuse peritoneal leiomyomatosis
Epidemiology:
Fewer than 150 cases have been reported in the literature to date. DPL occurs in adulthood and predominantly affects women.
Clinical description:
The majority of cases are asymptomatic, but clinical signs such as abdominal and pelvic pain, rectal or vaginal bleeding, and, more rarely, gastrointestinal disorders have been reported. Malignant transformation is rare, and a few cases of liver and lung metastases have been observed.
Etiology:
The etiology is unknown, but LPD appears to be a multifactorial disease, with hormonal (high estrogen and progesterone levels) or genetic factors leading to metaplasia of peritoneal mesenchymal cells. In some women, LPD may originate from fragments of uterine leiomyoma in the abdominal cavity after laparoscopic surgery.
Diagnostic Method:
Detection is based on imaging tests such as ultrasound and CT scans. The diagnosis is confirmed by biopsy of the nodules showing the presence of smooth muscle cells without atypia or necrosis, fibroblasts, and myofibroblasts.
Differential Diagnosis:
Differential diagnoses include parasitic leiomyomas, intravenous leiomyomatosis, and other primary or secondary peritoneal carcinomatosis.
Treatment:
Depending on the extent of the disease, the first-line treatment for LPD is surgical excision or cytoreduction.
Hormone use (such as oral contraceptives) should be discontinued. Systemic chemotherapy with doxorubicin and dacarbazine has been proposed as a treatment option in rare cases of unresectable or metastatic tumors.
Prognosis:
The prognosis is usually good, except for the deaths reported in a few cases of unresectable or metastatic tumors.
AMARAPE Scientific Advisory Board chaired by Professor Olivier Glehen (February 2025)
Primary peritoneal carcinoma
Primary peritoneal carcinoma (PPC) is a rare malignant tumor of the peritoneal cavity of extra-ovarian origin, clinically and histologically similar to high-grade serous ovarian carcinoma.
Synonyms:
PPC, extra-ovarian primary peritoneal carcinoma, papillary serous carcinoma of the peritoneum, primary serous peritoneal carcinoma, primary serous carcinoma of the peritoneum.
Epidemiology:
PPC accounts for approximately 10% of epithelial ovarian carcinomas. It is found almost exclusively in women. PPC can occur several years after an oophorectomy for benign disease or a prophylactic oophorectomy. The tumor appears in adulthood, with an average age of 60 at the time of diagnosis.
Clinical description:
Symptoms include abdominal mass, constipation, digestive disorders, nausea,
vomiting, anorexia, ascites, and weight loss.
Etiology:
The tumor develops in the peritoneum and spreads to the abdomen, pelvis, and ovary. CPP and serous ovarian carcinoma are histologically similar, and it is often impossible to determine the site of origin at an advanced stage when the ovaries, abdominal cavity, and fallopian tubes are all affected. PPC is epithelial in origin and probably derives from the embryonic coelomic epithelium. The fallopian tube is thought to be the primary site. Women with type 1 breast cancer gene (BRCA) mutations are at higher risk.
Diagnostic method:
Detection is based on imaging tests such as ultrasound. The diagnosis is confirmed by biopsy of the carcinomatous nodules, which identifies high-grade serous ovarian carcinoma.
Differential diagnosis:
The main differential diagnosis is epithelial ovarian cancer.
Treatment:
Treatment is multidisciplinary and must be carried out in a specialist center (RENAPE network): cytoreductive surgery (visceral resection and peritonectomy techniques) combined with hyperthermic intraperitoneal chemotherapy (HIPC) in certain patients (young, in good general health, and with a small tumor volume) after or following systemic chemotherapy (carboplatin and Taxol and/or Avastin and/or PARP inhibitor) if the disease is not amenable to optimal cytoreductive surgery.
Prognosis:
The prognosis is poor, similar to or worse than that of ovarian carcinoma.
AMARAPE Scientific Advisory Board chaired by Professor Olivier Glehen (February 2025)
Small cell desmoplastic tumor
Small cell desmoplastic tumor (SCDT) is an aggressive soft tissue cancer that typically affects the serous membranes of the abdominal-pelvic peritoneum, spreads to the omentum and lymph nodes, and disseminates hematogenously, mainly to the liver. An exceptional extra-serosal primary location has been reported. This tumor is extremely rare.
Synonyms:
Small round cell desmoplastic tumor
Epidemiology:
Only a few hundred cases have been reported worldwide since its first description in 1989. It predominantly affects men, adolescents, or young adults, with a ratio of four men to one woman.
Clinical description:
The symptoms and clinical signs are non-specific. The tumor manifests as abdominal pain, an increase in abdominal volume, dyspepsia and/or vomiting, and weight loss depending on the stage of the disease. A palpable abdominal mass, gastrointestinal obstruction, ascites, and hepatomegaly may be observed.
Etiology:
The tumor may originate from other primary sites such as the brain, thorax, lung, paratesticular region, ovaries, or nasal cavity, without characteristic clinical signs. The tumor appears to be of mesothelial origin. A specific translocation t(11;22)(p13;q12) is found in almost all cases: it juxtaposes the EWS gene with the WT1 tumor suppressor gene. However, the underlying molecular mechanism remains unknown. Several other associated chromosomal translocations have been described (t(5;19), t(X;16), and t(4;10)).
Diagnostic Method:
Diagnosis is difficult due to the rarity of the tumor and its resemblance to other small round cell tumors. Diagnosis is based on clinical examination, endoscopic examination (laparoscopy), and/or imaging tests (X-ray, thoracoabdominal-pelvic CT scan). Biopsy shows nests of poorly differentiated small round cells with little cytoplasm and hyperchromatic nuclei surrounded by desmoplastic stroma. The cells may have epithelial, mesenchymal, or neuronal differentiation. The diagnosis is confirmed by the immunophenotypic profile (tumor cells express cytokeratin, desmin, and neuron-specific enolase) and molecular identification of the EWS/WT1 translocation by FISH and RT-PCR.
Differential diagnosis:
The differential diagnoses include all small round cell tumors: Ewing’s sarcoma and other peripheral neuroectodermal tumors (PNETs), Wilms’ tumor, rhabdomyosarcoma, and undifferentiated carcinoma (see these terms).
Treatment:
Patients must be treated at a specialist center (RENAPE network): nearly 30% of desmoplastic tumors are misdiagnosed and therefore incorrectly treated. Treatment is based on intensive polychemotherapy (5 to 7 drugs) at high doses to reduce the tumor, followed by optimal cytoreductive surgery and abdominal radiotherapy. Prospective studies are underway to evaluate the role of hyperthermic intraperitoneal chemotherapy (HIPEC), maintenance chemotherapy, and targeted therapy.
Prognosis:
The prognosis is guarded. The median survival time is 17 months, and less than 20% of patients live more than 5 years after diagnosis.
Scientific advisory board chaired by Professor Olivier GLEHEN (February 2025)