Introduction

• Organomegaly is presumed on palpation of a large viscus on physical abdominal examination.
• Many patients are presented due to dysfunction of the affected organ or a neighboring structure that is suffering a mass effect. In some instances organomegaly is recognized as an incidental finding.
• Causes: multiple underlying causes; neoplasia is frequently recognized but is certainly not involved in the pathogenesis of all cases.
• Treatment: many cases are appropriate candidates for therapy but therapeutic decisions require a definitive diagnosis. It is important to note that imaging findings are rarely sufficient for diagnosis in these cases. Examples of exceptions include radiographic identification of gastric volvulus or pregnancy and ultrasonographic identification of intestinal intussusception.

Pathogenesis

Etiology

Liver

• Neoplasia Liver: neoplasia (primary or secondary).
• Hepatitis Liver: acute disease.
• Extramedullary hematopoiesis.
• Congestion, eg congestive heart failure Heart: congestive heart failure.
• Fatty infiltration, eg metabolic disease such as hyperadrenocorticism Hyperadrenocorticism or diabetes mellitus Diabetes mellitus.
• Hematoma.
• Cyst.

Spleen

• Neoplasia Spleen: neoplasia (primary or secondary).
• Drug induced, eg sedatives/anesthetics.
• Congestion, eg congestive heart failure Heart: congestive heart failure (torsion).
• Extramedullary hematopoiesis.
• Hematoma.
• Inflammation (rare).

Stomach

• Recent meal.
• Pyloric outflow obstruction Stomach: gastric outflow disease :
• • Pyloric stenosis Stomach: pyloric stenosis.
  • Neoplasia (gastric Stomach: neoplasia or pancreatic Pancreas: neoplasia of the exocrine pancreas (adenocarcinoma) ).
  • Foreign body Stomach: foreign body.
• Gastric dilatation Stomach: gastric dilatation / volvulus (GDV) syndrome.

Pancreas

• Neoplasia Pancreas: neoplasia.
• Pseudocyst.
• Acute necrotizing pancreatitis Pancreatitis: acute.

Bladder

• Outflow obstruction Urethra: obstruction (eg urolith, neoplasia).
• Dyssynergia Urinary incontinence.

Prostate

• Benign prostate hyperplasia Prostate: benign hyperplasia and hypertrophy.
• Neoplasia Prostate: neoplasia.
• Pseudocyst Prostate: cyst.
• Prostatitis Acute prostatitis.
• Paraprostatic cyst Prostate: cyst.

Kidney

• Inflammation, acute nephritis.
• Neoplasia Kidney: neoplasia.
• Cyst Kidney: polycystic disease.
• Hydronephrosis Hydronephrosis / hydroureter.
• Perirenal cyst.
• Hematoma.

Ureter

• Neoplasia Ureter: neoplasia.
• Megaureter Hydronephrosis / hydroureter often associated with ureteric ectopia Ureter: ectopic.
• Ureterocoele Ureterocoele.

Ovary

• Neoplasia Ovary: neoplasia.
• Cyst.

Uterus

• Pyometra Pyometra.
• Mucometra.
• Hemometra.
• Pregnancy.

Lymph nodes

• Neoplasia (primary, eg lymphoma Lymphoma or secondary, eg anal sac gland carcinoma Anal sac adenocarcinoma ).
• Lymphadenitis.
• Reactive hyperplasia.

Intestine

• Megacolon Megacolon
• Foreign body Intestine: linear foreign bodies.
• Neoplasia Small intestine neoplasia.
• Obstruction Intestine: obstruction.
• Intussusception Intussusception.

Adrenal gland

• Tumor.

Testicle

• Retained testicles are usually atrophied unless neoplastic Testicle: cryptorchidism.
• Neoplastic testicles can reach extremely large sizes before producing any clinical signs Testicle: neoplasia.

Masses not associated with organs

• Other abdominal masses need to be recognized so that they can be distinguished from organomegaly.
• Abscess often sublumbar associated with tracking foreign body, eg grass seed.
• Hematoma in mesentery, retroperitoneal space or body wall.
• Neoplasia in body wall (particularly lipoma Lipoma which may reach massive dimensions without significant clinical effect).

Diagnosis