Which of the following characterizes ductal carcinoma in situ?

Correct Answer: D

Rationale: The correct answer is that ductal carcinoma in situ is characterized by malignant cells that have not invaded the stroma, making it a cancer precursor with a higher risk for invasive cancer compared to lobular carcinoma in situ. Choice A is incorrect because ductal carcinoma in situ is more common than lobular carcinoma in situ. Choice B is incorrect as it only partially describes ductal carcinoma in situ without mentioning its potential for progression to invasive cancer. Choice C is incorrect because it does not capture the complete characteristics of ductal carcinoma in situ, which include the risk for invasive cancer.

Correct Answer: B

Rationale: Postoperative adhesions are a common cause of mechanical small intestine obstruction. Adhesions can form after abdominal surgery, causing bands of scar tissue that may twist or pull the intestines, leading to obstruction. This is a more common cause compared to infection, tumors, or foreign bodies. Infection may lead to inflammation but is not a typical cause of mechanical obstruction. Tumors and foreign bodies can cause blockages but are less common than postoperative adhesions.

Correct Answer: A

Rationale: Crohn's disease is a type of inflammatory bowel disease that can affect any part of the digestive tract. Right lower quadrant cramping is consistent with Crohn's disease as it commonly involves the terminal ileum, which is located in the right lower quadrant of the abdomen. Severe bloody diarrhea is more characteristic of ulcerative colitis, another type of inflammatory bowel disease. Nausea and vomiting are not specific symptoms of Crohn's disease. Crohn's disease can affect any part of the digestive tract, not just the rectum, so it is not accurate to say it mostly affects the rectum.

Correct Answer: B

Rationale: The correct answer is 'Both an adult male with a history of alcoholism and a middle-aged male who smokes a pipe.' Alcohol consumption and tobacco use, such as smoking a pipe, are well-known risk factors for developing oral cancer. These two factors significantly increase the likelihood of developing oral cancer compared to the other choices. Taking oral contraceptives, eating spicy foods regularly, and chewing gum frequently are not established risk factors for oral cancer, making them less likely to lead to the development of this type of cancer.

Correct Answer: A

Rationale: Truncal obesity with thin extremities is a classic manifestation of Cushing syndrome due to the redistribution of fat. Enlargement of face, hands, and feet is seen in conditions like acromegaly, not Cushing syndrome. Cachexia is a state of severe weight loss and muscle wasting, typically seen in conditions like cancer or advanced infections. Thick scalp hair is not typically associated with Cushing syndrome.