As the physician examines the abdomen, how can he or she recall all of the causes of a mass or swelling? The physician should consider the possibilities for the composition of the mass. It may be air, in which case the physician would think of air in the peritoneum with rupture of a viscus, particularly a peptic ulcer, or it may be air in the intestinal tract from focal or generalized distention, in which case the physician would recall gastric dilatation, intestinal obstruction related to numerous causes (see page 30), or paralytic ileus. The mass may be fluid, in which case the physician would recall fluid in the abdominal wall (anasarca), the peritoneum (ascites, page 28) and its various causes, and fluid (urine) accumulation in the bladder or intestine or cysts of other abdominal organs. The latter brings to mind ovarian, pancreatic, and omental cysts. The mass may be blood in the peritoneal wall, the peritoneum, or any of the organ systems of the abdomen. The mass may be a solid inorganic substance, such as the fecal accumulation in celiac disease and Hirschsprung disease. Finally, the mass may be a hypertrophy, swelling, or neoplasm of any one of the organs or tissues in the abdomen.

This is where anatomy comes in. In the abdominal wall, there may be an accumulation of fat (obesity). The liver may be enlarged by neoplasm or obstruction of its vascular supply (e.g., Budd–Chiari syndrome or cardiac cirrhosis) or by obstruction of the biliary tree with neoplasms or biliary cirrhosis. The spleen may become massively enlarged by hypertrophy, hyperplasia in Gaucher disease, infiltration of cells in chronic myelogenous leukemia and myeloid metaplasia, or by inflammation in kala azar. The kidney rarely enlarges to the point at which it causes a generalized abdominal swelling in hydronephrosis, but a Wilms tumor or carcinoma may occasionally become extremely large.

The bladder, as mentioned above, may be enlarged sufficiently to present a generalized abdominal swelling when it becomes obstructed, but a neoplasm of the bladder will not present as a huge mass. The uterus presents as a generalized abdominal mass in late stages of pregnancy, but ovarian cysts should be first considered in huge masses arising from the female genital tract. Pancreatic cysts and pseudocysts are possible causes of a generalized abdominal swelling, although they are usually localized to the right upper quadrant (RUQ) or epigastrium. It would be unusual for an aortic aneurysm to grow to a size sufficient to cause a generalized abdominal mass, but it is frequently mentioned in differential diagnosis texts.

The above method is one method of developing a differential diagnosis of generalized abdominal swelling or mass. Relying solely on anatomy and cross-indexing the various structures with the mnemonic MINT is another. This mnemonic is suggested as an exercise for the reader. Take each organ system as a tract. Thus, the gastrointestinal (GI) tract presents most commonly with a diffuse swelling in intestinal obstruction and paralytic ileus; the biliary tract and pancreas with hepatitis, neoplasms, and pancreatic pseudocysts. The urinary tract presents with a diffuse “mass” in bladder neck obstruction. The female genital tract may be the cause of a huge abdominal mass in ovarian cysts, neoplasms, and pregnancy. Apply the same technique to the spleen and abdominal wall to complete the picture.

There are, in addition, certain conditions that cause abdominal swelling that is more apparent than real. Lumbar lordosis causes abdominal protuberance, as does visceroptosis. A huge ventral hernia or diastasis recti may mimic an abdominal swelling. Psychogenic protrusion of the belly by straining is another cause.

When the clinician lays his or her hand on the RUQ and feels a mass, he or she should visualize the anatomy and the differential diagnosis should become clear. Proceeding from the skin, the physician encounters the subcutaneous tissue, fascia, muscle, peritoneum, liver, hepatic flexure of the colon, gallbladder, duodenum, pancreas, kidney, and adrenal gland. The blood vessels and lymphatics to these organs and the bile and pancreatic ducts should be
considered. Then, because masses are caused by a limited number of etiologies, apply the mnemonic MINT to each organ. The differential using these methods is developed in Table 1.

Skin malformations do not usually cause a mass, but inflammation of the skin is manifested by cellulitis and carbuncles, and neoplasms are manifested as carcinomas, both primary and metastatic. Trauma of the skin is usually manifested by obvious contusions or lacerations. A mass of the subcutaneous tissue may be a lipoma, fibroma, metastatic carcinoma, cellulitis, or contusion. A mass disease of the fascia is usually the result of a hernia. The causes of hepatomegaly are reviewed on page 220, but if the mass is in the liver, it is usually hepatitis, amebic or
septic abscess, carcinoma (primary or metastatic), contusion, or laceration. A Riedel lobe should not be mistaken for a large gallbladder. The hepatic flexure of the colon may be enlarged by diverticulitis, carcinoma, granulomatous colitis, contusion, or volvulus. Malrotation may cause a mass in infants. A retrocecal appendix should not be forgotten here either.

An enlarged gallbladder accounts for the mass in the RUQ in many cases. The enlargement may be caused by cholecystitis, obstruction of the neck of the cystic duct by a stone causing gallbladder hydrops, Courvoisier–Terrier syndrome caused by obstruction of the bile duct by carcinoma of the head of the pancreas, or cholangiocarcinoma.

The pancreas may be enlarged in M—Malformations by congenital or acquired pancreatic cysts, I—Inflammation of an acute or chronic pancreatitis, N—Neoplasm, and T—Traumatic pseudocysts.

A duodenal diverticulum is not usually felt as a mass, but a perforated duodenal ulcer may manifest itself by a palpable subphrenic abscess in the right anterior intraperitoneal pouch. Malformations of the kidney often cause hydronephrosis, whereas inflammation may cause a perinephric abscess and thus an RUQ mass. Carcinoma or Wilms tumor of the kidney is frequently responsible for a large kidney.

Carcinoma of the adrenal gland is not usually palpable until late in the disease process, but a neuroblastoma is palpable early. Other lesions of the adrenal gland are not usually associated with a mass.

Aneurysms, emboli, and thromboses of the vessels supplying these organs usually do not produce a mass, but a thrombosis of the hepatic vein (the well-known Budd–Chiari syndrome) causes hepatomegaly, and emboli and thrombi of the mesenteric vessels of the colon may cause focal enlargement from obstruction and infarction. Visualizing the lymphatics should recall Hodgkin lymphoma in the portal area.

The differential diagnosis for left upper quadrant (LUQ) masses is not a great deal different from that of the RUQ. The anatomy is similar: Just replace the liver with the spleen and the gallbladder with the stomach. The presence of the aorta on the side of the abdomen should not be forgotten. Again, anatomy is the key, as shown in Table 2. Cross-index the various organs and tissues with the etiologies using MINT as the mnemonic.

Anatomy is once again the key to developing a differential diagnosis of a right lower quadrant (RLQ) mass. Underneath the skin, subcutaneous tissue, fascia, and muscle lie the cecum, appendix, terminal ileum, iliac artery and vein, and ileum. In the female, the fallopian tube and ovary should be included. Occasionally a ptosed kidney also will be felt here. Now, apply the etiologic mnemonic MINT to each organ, and you should have a reliable differential diagnosis, like that in Table 3. The important lesions to remember here are the following:

The lymph nodes may be involved with tuberculosis or actinomycosis. The cecum may also be enlarged by accumulation of Ascaris or other parasites. The omentum can contribute to adhesions of the bowel to form a mass, or it may develop cysts.

To quickly develop a list of etiologies of a left lower quadrant (LLQ) mass, visualize the anatomy of the area. Compared to the RUQ, the number of organs there is few. Beneath the skin, subcutaneous tissue, fascia, and muscle are the sigmoid colon, the iliac artery and veins, the aorta, and the ileum. In the female, one must remember the fallopian tube and ovary. Occasionally, the kidney drops into this region (nephroptosis) and the omentum may cause adhesion. Now apply the mnemonic MINT to each organ and the list of possibilities in Table 4 is completed without any difficulty.

Lesions of the skin and fascia are similar to those in upper quadrants with one exception: Because of the inguinal and femoral canals, hernias (especially indirect inguinal hernias) are much more frequent. In the sigmoid colon the following conditions should be considered:

This list excludes an important consideration, that of fecal impaction. If the patient is given an enema, the mass will often disappear. Less common causes of masses in the
sigmoid colon are tuberculosis and amebiasis and other parasites.

There may be aneurysms of the iliac artery or aorta and thrombosis of the iliac vein, although the latter is not usually palpable. The iliac lymph nodes may enlarge from Hodgkin lymphoma, metastatic carcinoma, or tuberculosis. Tubal and ovarian lesions that should come to mind are malignant and benign ovarian cysts, tubo-ovarian abscesses, ectopic pregnancy, and endometriosis. A sarcoma or other tumor of the ileum may be palpable, but abscesses of the sacroiliac joint are rarely palpable.

In developing the differential diagnosis of an epigastric mass, one merely needs to visualize the anatomy of the epigastrium from skin to spine. The conditions are presented in outline form in Table 5, but the important conditions are emphasized in the following discussion.

More physicians have been fooled by a hypogastric mass than by a mass in any other area. How many times can you recall the mass disappearing on the operating table after catheterization of the bladder? More often than not, the mass is more apparent than real because of a lumbar lordosis or a diastasis recti.

Anatomy is the key to the differential diagnosis. There are not many organs here normally. Under the skin, subcutaneous tissue, fascia, and rectus abdominis muscles, the bladder, terminal aorta, and lumbosacral spine may be palpated in a thin male. In the female, the uterus may be palpated on bimanual pelvic examination. When there is visceroptosis, the transverse colon will be palpated.

Under pathologic conditions, however, the lymph nodes, sigmoid colon, fallopian tube and ovary, and small intestines may be palpated as well as a pelvic kidney. Applying the mnemonic MINT to these organs results in the extensive differential diagnosis in Table 6. The discussion that follows mentions only the most significant causes of a hypogastric mass.

Lipomas of the skin, ventral hernias, and diastasis recti form the most frequently encountered disorders in the covering of the hypogastrium. The bladder may be obstructed by strictures and prostatism (see page 351), but bladder carcinoma and stones may also be palpable. Bladder rupture should be considered in trauma to the perineum. The uterus may be enlarged by pregnancy, endometritis, fibroid, choriocarcinoma, or endometrial carcinoma. An ovarian or tubal mass may be caused by a benign or malignant ovarian cyst, an ectopic pregnancy, or a tubo-ovarian abscess. The aorta may present as a mass in aneurysms or thrombosis and severe arteriosclerosis of the terminal aorta. Finally, the lumbosacral spine may present as a hypogastric mass in the severe lordosis of Pott disease, spondylolisthesis, metastatic carcinoma, and lumbar spondylosis. The preaortic lymph nodes may greatly enlarge in tuberculosis, Hodgkin lymphoma, and metastatic carcinoma. If the transverse colon drops to the hypogastrium, a carcinoma or inflamed and abscessed diverticulum may be felt. Volvulus may present a mass here.

Ascites from cirrhosis of the liver, ruptured abdominal viscus, or bacterial or tuberculous peritonitis is often encountered and is difficult to differentiate from an ovarian cyst and a distended bladder. Careful percussion or ultrasonic evaluation will be extremely helpful, but a peritoneoscopy or a peritoneal tap in the lateral quadrants may be necessary.

The GI tract is the only “organ” that really covers the abdomen from one end to the other. Anything that causes an irritation of all or a large portion of this “tube” may cause generalized abdominal pain. Thus, gastritis, viral and bacterial gastroenteritis, irritable bowel syndrome, ulcerative colitis, and amebic colitis fall into this category. The remainder of the causes of generalized abdominal pain can be developed by using the mnemonic ROS with the anatomy of the entire abdomen.

When faced with a patient with diffuse abdominal pain, think of R for ruptured viscus. Now take each organ and consider the possibility of its having ruptured. Thus, the stomach and duodenum suggest a ruptured peptic ulcer; the pancreas, an acute hemorrhagic pancreatitis; the gallbladder, a ruptured cholecystitis. The liver and spleen usually rupture from trauma, whereas the fallopian tube may rupture from an ectopic pregnancy. The colon ruptures from diverticulitis, ulcerative colitis, or carcinoma. What is the one thing that should make the physician suspect a ruptured viscus? Rebound tenderness is the answer. In addition, one
or both testicles may be drawn up (Collins sign). If only the right testicle is drawn up, suspect a ruptured appendix or peptic ulcer. If only the left is drawn up, suspect a ruptured diverticulum. If both are drawn up, suspect pancreatitis or a generalized peritonitis.

Now take the letter O. This signifies intestinal obstruction. Think of adhesion hernia, volvulus, paralytic ileus, intussusception, fecal impaction, carcinoma, mesenteric infarction, regional ileitis, and malrotation. The best way to recall all these is with the mnemonic VINDICATE.

Next take the letter S. This signifies the systemic diseases that may irritate the intestines, the peritoneum, or both. Once again the mnemonic VINDICATE will remind one to recall the important offenders.

The patient is complaining of RUQ pain and you cannot just give him or her a bag of pills and send him or her home.

The patient’s condition may be serious. However, you are in a hurry to get out of the office because you have another important appointment. What do you do? The key is to visualize the anatomy. Imagine the liver, gallbladder, bile ducts, hepatic flexure of the colon, duodenum, and head of the pancreas. Surrounding these are the skin, fascia, ribs, and thoracic and lumbar spine, with the intercostal nerves and arteries and abdominal muscle.

Pain is usually from inflammation, trauma, or infarction. The patient gives no history of trauma, but he or she could have a contusion of the muscle from coughing hard.
That is not likely, however, unless the patient has other symptoms of the respiratory tract.

The possible sources of inflammation should be narrowed down first. The liver can be inflamed from hepatitis (most likely viral), the gallbladder from cholecystitis (most likely induced by stones and bacteria), or the bile ducts from cholangitis. The colon may be involved with diverticulitis, a segment of granulomatous colitis, or perhaps there is a retrocecal appendix. The duodenum, of course, would most likely have a peptic ulcer which could cause an obstruction or a perforation if the patient is vomiting, or pallor and shock if the patient is bleeding. The pancreas could be inflamed with pancreatitis, especially if the patient drinks alcohol.

These are the most important intra-abdominal considerations, but if the mnemonic VINDICATE in Table 7 were applied one might not forget the Budd–Chiari syndrome (thrombosis of the hepatic veins), portal vein thrombosis, or pylephlebitis; these are rare. In addition, toxic hepatitis from isoniazid, thorazine, and erythromycin estolate (Ilosone), for example, can be painful. Collagen diseases affecting the liver are another possibility.

Now let us round out the differential diagnosis with extra-abdominal disorders. The skin may be involved with herpes zoster or cellulitis. A fascial rent may cause a hernia, particularly if there was previous upper abdominal surgery. Compression of the nerve roots by a herniated disc, thoracic spondylosis, or a spinal cord tumor is possible, but unlikely. Systemic conditions, such as lead colic and porphyria, and involvement of another organ, such as the kidney, must be considered (pyelonephritis or renal colic).