Paul, a 60-year old man, complains of rectal bleeding for the last 24 hours.  He has experienced four bloody stools in the last several hours and is beginning to weaken.  Prior to this episode he was constipated.  He is admitted to the hospital, where all the results of lab and diagnostic studies are within normal limits except for the following:
 

Hemoglobin: 9 g/dl
Hematocrit: 25
Barium enema: reveals a narrowing of a small portion of the descending colon
Colonoscopy: mass detected in the descending colon

How would you diagnose this condition?
What is the physiological or anatomical cause of the problem?
What treatment would you recommend for this man?
 

Jane, a 30 year old teacher, tells her physician she has been experiencing bouts of painful abdominal cramping, gas and diarrhea during the last 6 months for unknown reasons. The episodes are short-lived and sporadic and are associated with meals such as fast foods, lobster dinner, and fried chicken.  After a special lobster dinner with her fiancee she vomited.  A stool specimen is negative for bacteria or parasites.  Blood analysis reveals normal results except for a total serum bilirubin level of 2.0 mg.dL.  Urinalysis revealed bilirubin as well. 

How would you diagnose this condition?
What is the physiological or anatomical cause of the problem? 
What treatment would you recommend for this woman?