A 51-year-old man presents with iron deficiency anemia and occasional blood
in his stool. He has no abdominal pain, no change in appetite, no diarrhea or
constipation, no melena, and no loss of weight. The patient denies any nausea
Past medical history is positive for asthma. He is on no medication. There
is no family history of cancer. Social history is negative for smoking. He
consumes 2 oz of alcohol per week. The patient is employed as a salesman and
His vital signs are stable. Physical exam is negative for dermatological
findings. He has a normal cardiorespiratory exam. His abdomen is soft, without
masses, tenderness, or organomegaly. His rectal exam is negative including
guaiac. Laboratory data are significant for hemoglobin of 12.5 g/dL and mean
corpuscular volume (MCV) of 76 fL. Serum iron and ferritin levels are
decreased. Colonoscopy reveals the abnormality shown in the photograph at the
- The possible explanations for this patient’s iron deficiency anemia
a. Carcinoma of the colon
b. Cecal angiodysplasia
c. Diverticulosis of the colon
e. Pancreatic cancer
- The abnormality seen on colonoscopy is characteristic of:
a. A malignant tumor
c. An angiodysplasia
d. A parasite
e. A retained suture
The correct answers to question 1 are a, b, and d. The differential diagnosis of
iron deficiency anemia in this patient includes carcinoma and angiodysplasia of
the colon and malabsorption. Diverticulosis of the colon and pancreatic cancer
would not usually be associated with iron deficiency. Although the patient has
little symptomatology to suggest malabsorption, selective malabsorption of iron
can occur. For example, some patients with celiac sprue present with isolated
iron deficiency anemia.
The correct answer to question 2 is d. The endoscopic photograph reveals a worm-like
structure adherent to the mucosa in the cecum. It has the typical appearance of
This nematode, also known as whipworm, is one of the most common human
parasites. Infection is caused when soil-containing eggs are swallowed. The
highest prevalence is in tropical Asia, Africa, and South America.
The eggs hatch in the small intestine and migrate to the cecum where the
anterior end of the worm embeds into the epithelium. It takes approximately 3
months for the eggs to develop into adults with a life expectancy of 3 years.
Adult worms range from 3 to 5 cm in length. The females can produce in excess
of 10,000 eggs per day.
Parasitic diseases of the liver and intestines. Gastroenterol Clin North
Am 25:579-597, 1996.