Symptoms of peritoneal mesothelioma include weight loss and abdominal pain and swelling due to a buildup of fluid in the abdomen. Other symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia, and fever. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.

As differential diagnoses, a subphrenic abscess, bowel interposed between diaphragm and liver (Chilaiditi syndrome), and linear atelectasis at the base of the lungs can simulate free air under the diaphragm on a chest X-ray.

Peritoneal mesothelioma is the name given to the cancer that attacks the lining of the abdomen. This type of cancer affects the lining that protects the contents of the abdomen and which also provides a lubricating fluid to enable the organs to move and work properly.

The peritoneum is made of two parts, the visceral and parietal peritoneum. The visceral peritoneum covers the internal organs and makes up most of the outer layer of the intestinal tract. Covering the abdominal cavity is the parietal peritoneum.

When present, pneumoperitoneum can often be seen on projectional radiography, but small amounts are often missed, and CT scan is nowadays regarded as a criterion standard in the assessment of a pneumoperitoneum. CT can visualize quantities as small as 5 cm³ of air or gas.

Signs that can be seen on projectional radiography are the "double wall sign" (also called "Rigler's sign") and the "football sign".

The "double wall sign" marks the presence of air on both sides of the intestine. However, a false double wall sign can result from two loops of bowel being in contact with one another. The sign is named after Leo George Rigler. It is not the same as Rigler's triad.

The "football sign" is when the abdomen appears as a large oval radiolucency reminiscent of an American football on a supine projectional radiograph. The football sign is most frequently seen in infants with spontaneous or iatrogenic gastric perforation causing pneumoperitoneum. It is also seen in bowel obstruction with secondary perforation, as in Hirschprung disease, midgut volvulus, meconium ileus and intestinal atresia. Iatrogenic causes like endoscopic perforation may also give football sign.

Meigs syndrome may mimic other conditions, since it is tumor arising from ovaries, pathology of any organs present in the abdomen may show a similar set of symptoms. Various gynecological disorders of the uterus such as endometrial tumor, sarcoma, leiomyoma (pseudo-Meigs syndrome); fallopian tube disorders such as hydrosalpinx, granulomatous salpingitis, fallopian tube malignancy; ovarian disorders such as serous, mucinous, endometrioid, or clear cell carcinoma, Brenner tumor, granulosa cell tumor, stromal tumor, dysgerminoma, fibroma, or metastatic tumor to the ovary.

Meigs syndrome is characterized by the presence of a benign solid ovarian tumor associated with ascites and right hydrothorax that disappear after tumor removal. Non-gynecological manifestations include:

ascites, portal vein obstruction, inferior vena cava obstruction, hypoproteinaemia, thoracic duct obstruction, tuberculosis, amyloidosis, pancreatitis, ovarian hyperstimulation, pleural effusion transudative, congestive heart failure, metastatic tumors to the peritoneal surfaces, collagen-vascular disease, and cirrhosis of the liver.

These entities must be clinically excluded.

Clinical condition characterized by ovarian mass, ascites, and right-sided pleural effusion.Ovarian malignancy and the

other causes (see “Differential Diagnosis”) of pelvic mass, ascites, and pleural effusion to be considered, History of early satiety,

weight loss with increased abdominal girth, bloating, intermittent abdominal pain, dyspnea, nonproductive cough may help in differentiating potential local factor causing such symptoms.

Signs and symptoms of pseudomyxoma peritonei may include abdominal or pelvic pain and/or bloating, distension, digestive disorders, weight changes, increased girth, and infertility.

In medicine, Meigs' syndrome, also Meigs syndrome or Demons-Meigs syndrome, is the triad of ascites, pleural effusion, and benign ovarian tumor (ovarian fibroma, fibrothecoma, Brenner tumour, and occasionally granulosa cell tumour). Meigs' syndrome resolves after the resection of the tumor. Because the transdiaphragmatic lymphatic channels are larger in diameter on the right, the pleural effusion is classically on the right side. The causes of the ascites and pleural effusion are poorly understood. Atypical Meigs' syndrome, characterized by a benign pelvic mass with right-sided pleural effusion but without ascites, can also occur. As in Meigs syndrome, pleural effusion resolves after removal of the pelvic mass.

A pancreatic fistula is an abnormal communication between the pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic ducts. An "external" pancreatic fistula is one that communicates with the skin, and is also known as a pancreaticocutaneous fistula, whereas an internal pancreatic fistula communicates with other internal organs or spaces. Pancreatic fistulas can be caused by pancreatic disease, trauma, or surgery.

Marked recent weight loss is a major clinical manifestation, and unresponsiveness of the ascites to diuretics is an additional diagnostic clue.

Pseudomyxoma peritonei (PMP) is a clinical condition caused by cancerous cells (mucinous adenocarcinoma) that produce abundant mucin or gelatinous ascites. The tumors cause fibrosis of tissues and impede digestion or organ function, and if left untreated, the tumors and mucin they produce will fill the abdominal cavity. This will result in compression of organs and will destroy the function of colon, small intestine, stomach, or other organs. Prognosis with treatment in many cases is optimistic, but the disease is lethal if untreated, with death by cachexia, bowel obstruction, or other types of complications.

This disease is most commonly caused by an appendiceal primary cancer (cancer of the appendix); mucinous tumors of the ovary have also been implicated, although in most cases ovarian involvement is favored to be a metastasis from an appendiceal or other gastrointestinal source. Disease is typically classified as low- or high-grade (with signet ring cells). When disease presents with low-grade histologic features the cancer rarely spreads through the lymphatic system or through the bloodstream.

Patients will present with a sudden onset of cramps/abdominal pain or a 'stitch'. The pain localises in the area of the umbilicus and can radiate to the lumbar and surrounding regions.

In medicine, Valentino's syndrome is pain presenting in the right lower quadrant of the abdomen caused by a duodenal ulcer with perforation through the retroperitoneum.

It is named after Rudolph Valentino who presented with right lower quadrant pain which turned out to be perforated peptic ulcer. He subsequently died from an infection inspite of surgery to repair the perforation. The pain is caused by gastric and duodenal fluids that tend to settle in the right paracolic gutter causing peritonitis and RLQ pain.

Patients with perforated Valentino's syndrome usually present with a sudden onset of severe, sharp abdominal pain which is reminiscent of appendicitis. Most patients describe generalized pain; a few present with severe epigastric pain. As even slight movement can tremendously worsen their pain, these patients assume a fetal position. Abdominal examination usually discloses generalized tenderness, rebound tenderness, guarding, and rigidity. However, the degree of peritoneal findings is strongly influenced by a number of factors, including the size of perforation, amount of bacterial and gastric contents contaminating the abdominal cavity, time between perforation and presentation, and spontaneous sealing of perforation.

These patients may also demonstrate signs and symptoms of septic shock, such as tachycardia, hypotension, and anuria. Not surprisingly, these indicators of shock may be absent in elderly or immunocompromised patients or in those with diabetes. Patients should be asked if retching and vomiting occurred before the onset of pain.

A chylothorax (or chyle leak) is a type of pleural effusion. It results from lymph formed in the digestive system called chyle accumulating in the pleural cavity due to either disruption or obstruction of the thoracic duct.

In people on a normal diet, this effusion can be identified by its turbid, milky white appearance, since chyle contains high levels of triglycerides. It is important to distinguish chylothorax from pseudochylothorax (pleural effusions high in cholesterol), which has a similar appearance, but is caused by more chronic inflammatory processes, and has a different treatment.

A peritoneal inclusion cyst is a cyst-like structure that appears in the pelvis due to non neoplastic reactive mesothelial proliferation, often as a consequence of prior episodes of pelvic inflammation, as can occur in pelvic inflammatory disease. It has the potential to mimic ovarian cysts, hydrosalpinx or even malignancy, due to its nonspecific anechoic appearance.

The condition is rare but serious, and appears in all mammals. It results from leakage of lymph fluid from the thoracic duct (or one of its tributaries). This can result from direct laceration (e.g., from surgery) or from nontraumatic causes. The most common nontraumatic cause is malignancy, especially lymphoma. Less common is left-heart failure, infections, and developmental abnormalities such as Down syndrome and Noonan syndrome.

Omental infarction, or omental torsion, is an acute vascular disorder which compromises tissue of the greater omentum—the largest peritoneal fold in the abdomen.

In medicine, the Sister Mary Joseph nodule or more commonly node, also called Sister Mary Joseph sign, refers to a palpable nodule bulging into the umbilicus as a result of metastasis of a malignant cancer in the pelvis or abdomen.

Gastrointestinal malignancies account for about half of underlying sources (most commonly gastric cancer, colonic cancer or pancreatic cancer, mostly of the tail and body of the pancreas), and men are even more likely to have an underlying cancer of the gastrointestinal tract. Gynecological cancers account for about 1 in 4 cases (primarily ovarian cancer and also uterine cancer). Nodules will also, rarely, originate from appendix cancer spillage Pseudomyxoma peritonei. Unknown primary tumors and rarely, urinary or respiratory tract malignancies cause umbilical metastases. How exactly the metastases reach the umbilicus remains largely unknown. Proposed mechanisms for the spread of cancer cells to the umbilicus include direct transperitoneal spread, via the lymphatics which run alongside the obliterated umbilical vein, hematogenous spread, or via remnant structures such as the falciform ligament, median umbilical ligament, or a remnant of the vitelline duct. Sister Mary Joseph nodule is associated with multiple peritoneal metastases and a poor prognosis.

Underlying causes include gastric ulcers, duodenal ulcers, appendicitis, gastrointestinal cancer, diverticulitis, inflammatory bowel disease, superior mesenteric artery syndrome, trauma and ascariasis. Typhoid fever, non-steroidal anti-inflammatory drugs, ingestion of corrosives may also be responsible.

A hydrocele is an accumulation of serous fluid in a body cavity. A hydrocele testis is the accumulation of fluids around a testicle. It is often caused by fluid secreted from a remnant piece of peritoneum wrapped around the testicle, called the tunica vaginalis. Provided there is no hernia present, hydrocoeles below the age of 1 year usually resolve spontaneously. Primary hydrocoeles may develop in adulthood, particularly in the elderly and in hot countries, by slow accumulation of serous fluid, presumably caused by impaired reabsorption, which appears to be the explanation for most primary hydroceles, although the reason remains obscure. A hydrocele can also be the result of a plugged inguinal lymphatic system caused by repeated, chronic infection of "Wuchereria bancrofti" or "Brugia malayi", two mosquito-borne parasites of Africa and Southeast Asia, respectively. As such, the condition would be a part of more diffuse sequelae commonly referred to as elephantiasis, which also affects the lymphatic system in other parts of the body.

The swelling is soft and non-tender, large in size on examination, and the testis cannot usually be felt. The presence of fluid is demonstrated by trans illumination. These hydrocoeles can reach a huge size, containing large amount of fluid, as these are painless and are often ignored. They are otherwise asymptomatic, other than size and weight, causing inconvenience. However the long continued presence of large hydroceles causes atrophy of testis due to compression or by obstructing blood supply. In most cases, the hydrocele, when diagnosed early during complete physical examination, are small and the testis can easily be palpated within a lax hydrocele. However Ultrasound imaging is necessary to visualize the testis if the hydrocele sac is dense to reveal the primary abnormality. But these can become large in cases when left unattended. Hydroceles are usually painless, as are testicular tumors. A common method of diagnosing a hydrocele is by attempting to shine a strong light (transillumination) through the enlarged scrotum. A hydrocele will usually pass light, while a tumor will not (except in the case of a malignancy with reactive hydrocele).

Signs and symptoms may include a sudden pain in the epigastrium to the right of the midline indicating the perforation of a duodenal ulcer. In a gastric ulcer perforation creates a history of burning pain in epigastrium, with flatulence and dyspepsia.

In intestinal perforation, pain starts from the site of perforation and spreads across the abdomen.

Gastrointestinal perforation results in severe abdominal pain intensified by movement, nausea, vomiting and hematemesis. Later symptoms include fever and or chills. In any case, the abdomen becomes rigid with tenderness and rebound tenderness. After some time the abdomen becomes silent and heart sounds can be heard all over. Patient stops passing flatus and motion, abdomen is distended.

The symptoms of esophageal rupture may include sudden onset of chest pain.

In NSF, patients develop large areas of hardened skin with fibrotic nodules and plaques. NSF may also cause joint contractures resulting in joint pain and limitation in range of motion. In its most severe form, NSF may cause severe systemic fibrosis affecting internal organs including the lungs, heart and liver.

Mesothelial hyperplasia is a hyperplasia of mesothelial cells in serous membranes (pleura, pericardium, peritoneum).

Mesothelial hyperplasia is usually an incidental finding during peritoneal examination during laparotomy or laparoscopy. Grossly, mesothelial hyperplasia is characterized by the presence of small white nodules or flat plaques on the serous surface.

Cytologic features of serous carcinoma are:

- Marked intragroup nuclear pleomorphism.

- Macronucleoli.

- "Knobby" group borders (in large groups).

- Hydropic vacuoles.

Symptoms of serous carcinoma may include:

- Discomfort/pain or bloating in abdomen

- Frequent urination

- Weight loss

The main manifestations of peritonitis are acute abdominal pain, abdominal tenderness and abdominal guarding, which are exacerbated by moving the peritoneum, e.g., coughing (forced cough may be used as a test), flexing one's hips, or eliciting the Blumberg sign (a.k.a. rebound tenderness, meaning that pressing a hand on the abdomen elicits less pain than releasing the hand abruptly, which will aggravate the pain, as the peritoneum snaps back into place). Rigidity (involuntary contraction of the abdominal muscles) is the most specific exam finding for diagnosing peritonitis (+ likelihood ratio: 3.9). The presence of these signs in a patient is sometimes referred to as peritonism. The localization of these manifestations depends on whether peritonitis is localized (e.g., appendicitis or diverticulitis before perforation), or generalized to the whole abdomen. In either case, pain typically starts as a generalized abdominal pain (with involvement of poorly localizing innervation of the visceral peritoneal layer), and may become localized later (with the involvement of the somatically innervated parietal peritoneal layer). Peritonitis is an example of an acute abdomen.