A 67-year-old male smoker was seen in the ER for evaluation of cough and treated for acute bronchitis. A CXR done at that time prompted a referral to the chest clinic. The patient gives a past history of myocardial infarction, but at the moment is asymptomatic. BP is 128/80 and cardiopulmonary exam is unremarkable. PPD is 7 mm. CXR is shown in. The likely diagnosis is

**Core Concept**
The patient's presentation, including a positive PPD (purified protein derivative) of 7 mm, and the chest X-ray (CXR) findings, suggests a diagnosis related to tuberculosis (TB) or another granulomatous disease. This case highlights the importance of considering TB in the differential diagnosis, especially in high-risk populations such as smokers and those with a history of myocardial infarction.

**Why the Correct Answer is Right**
The patient's 7 mm PPD is considered positive in a low-risk individual, indicating an immune response to TB. However, the patient's clinical presentation and CXR findings are more suggestive of a focal lesion, such as a granuloma or a tumor, rather than typical pulmonary TB. The presence of a focal lesion is a key feature that distinguishes this diagnosis from typical TB.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not account for the patient's positive PPD and focal CXR findings. While TB can present with focal lesions, the combination of these findings and the patient's clinical presentation suggests an alternative diagnosis.

**Option B:** This option is incorrect because it does not take into account the patient's history of smoking and the presence of a focal lesion on CXR. While TB can occur in smokers, the focal lesion and positive PPD suggest a different diagnosis.

**Option C:** This option is incorrect because it does not consider the patient's positive PPD and focal CXR findings. While lung cancer can present with focal lesions, the combination of these findings and the patient's clinical presentation suggests an alternative diagnosis.

**Clinical Pearl / High-Yield Fact**
The key to this question is to remember that a positive PPD can be seen in a variety of conditions, including TB, sarcoidosis, and other granulomatous diseases. A focal lesion on CXR, in conjunction with a positive PPD, suggests a diagnosis other than typical pulmonary TB.

**Correct Answer: C. Lung cancer.**

✓ Correct Answer: D. Left ventricular aneurysm