Palpable asymptomatic abdominal masses

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19 Palpable asymptomatic abdominal masses

Case

Mrs PA, a 45-year-old previously well woman presented to her general practitioner for a health check as part of a life insurance renewal. She denied any current illness or symptom, but when her general practitioner carried out an abdominal examination a mass was palpated in the right upper quadrant. The mass was smooth, slightly tender and moved with respiration, suggesting it arose in the liver. Following first principles, her doctor first of all revisited her medical history and noted that Mrs X had been on the oral contraceptive pill for more than 20 years. Furthermore, on close questioning she admitted to intermittent low grade abdominal discomfort in the right upper quadrant over several years, but a little more frequently over the last few months. However, her general practitioner could not identify any other hepatic disease risk factor in her history, such as intravenous drug use or other exposure to hepatitis B or C infection, or exposure to hydatid disease, and could find no other physical abnormality, in particular no evidence of chronic liver disease. Mrs X was referred for liver function tests, viral screens and an abdominal ultrasound scan. Her transaminase levels were mildly elevated, hepatitis B and C serology were negative and there was a solid mass seen on ultrasound scanning. Mrs X was referred to a multidisciplinary hepatology unit and, after more detailed investigation, was eventually found to have a 12-cm mass protruding from the inferior margin of hepatic segment 5. The imaging characteristics including the presence of a central scar were consistent with focal nodular hyperplasia, thought to be unrelated to her oral contraceptive pill consumption. After discussion with a hepatologist, with a hepatic surgeon and with her general practitioner and family, Mrs X elected to undergo surgery for removal of the mass. Subsequent histopathology confirmed the diagnosis of focal nodular hyperplasia. Her recovery was uneventful.

Introduction

The aim of this chapter is to give guidelines to assist clinicians in the five most common clinical scenarios within which palpable asymptomatic abdominal masses are detected:

Other chapters in this book are orientated to evaluation of symptomatic abdominal masses, abdominal distension and lumps in the groin. Chapter 26 discusses masses detected as incidental findings on abdominal imaging (incidentalomas).

Documenting the Finding of an Abdominal Mass

Masses within the Abdominal Wall

The different types of abdominal wall hernias and their features are listed in Box 19.1. Abdominal wall hernias are generally easy to characterise as a cough impulse is usually present, the hernia may present in a characteristic position and it may be possible to reduce the hernia. To separate other masses found within the abdominal wall from masses within the abdominal cavity, ask the patient to contract the anterior abdominal muscles by lifting his or her head from the examining couch with hands behind head, or to straight leg raise both legs simultaneously while keeping the head on the bed. This may help to define the mass as follows:

A mass within the abdominal cavity (the peritoneal cavity) will be made less distinct, less easy to palpate and may disappear altogether until the abdominal wall muscles are relaxed again.

Retroperitoneal Masses

The retroperitoneal region is subdivided into five regions:

Intraabdominal Masses

Site

On the basis of position (Fig 19.1), we can start to define the likely organ of origin of an intraabdominal mass as shown in Table 19.1. However, we cannot be certain of the organ of origin of a palpable mass on the basis of its position alone. Organs do not necessarily enlarge concentrically from a fixed point. The pattern of enlargement may be determined by surrounding structures, by retroperitoneal attachments and by the pathological process responsible for the organ enlargement. The liver, for example, is limited by the diaphragm along the superior surface and by the diaphragm and ribs along the lateral surface and so tends to enlarge downwards and inwards. The uterus and bladder are limited by the pelvic walls laterally and below and so tend to enlarge upwards in the midline. The kidneys, aorta and pancreas are retroperitoneal and limited behind by the posterior abdominal wall and so tend to expand from their original site in all directions except posterior. An enlarged segment of small bowel is usually not found in the upper reaches of the abdomen because the transverse mesocolon, the transverse colon and the greater omentum are attached to retroperitoneal tissues along a horizontal line at the level of the inferior border of the pancreas. These three organs tend to form a barrier restricting upward migration of small bowel masses.

Table 19.1 Organ of origin of intraabdominal masses by region

Right hypochondrium Epigastrium Left hypochondrium
Right lobe of liver Stomach Spleen
Gall bladder Left lobe of liver Pancreas
  Pancreas Stomach
  Lymph nodes  
  Aorta  
Right lumbar region Periumbilical Left lumbar
Ascending colon Omentum Descending colon
Right kidney Transverse colon Left kidney
  Aorta  
  Retroperitoneal nodes  
Right iliac fossa Hypogastrium Left iliac fossa
Appendix Bladder Sigmoid colon
Caecum Uterus Iliac aneurysm
Iliac aneurysm Right and left ovary Left ovary
Right ovary   Iliac nodes
Iliac nodes    

Strictly retroperitoneal in position

A single pathological process may have focal or diffuse effects in a given organ and may have different effects on the different organs involved. A cancer of the sigmoid colon may become fixed to the posterior abdominal wall by local invasion. Omental metastatic deposits from the same sigmoid colon cancer will not move with respiration but may be relatively mobile on palpation. Hepatic metastatic deposits from the same cancer may move with respiration as the liver moves, but will not move on palpation.

An enlarged organ may come to fill several adjacent abdominal regions if the degree of enlargement is great. Thus, in the third trimester of pregnancy, an enlarged pregnant uterus can be expected to fill the hypogastrium, the periumbilical region and part of the epigastrium.

The likely organ of origin may be defined by the position of the mass as in Table 19.1.

Discriminating clues that may be found on examination and that the patient may report on closer questioning may help establish the causative process. See Table 19.2 and Box 19.2.