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 and vomiting.
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(Drug information on alcohol) per week. The patient is employed as a salesman and travels worldwide.
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 right.
- 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 Trichuris trichiura.
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.