A 25 year old man presented with fever, cough, expectoration and breathlessness of 2 months duration. Contrast enhanced computed tomography of the chest showed bilateral upper lobe fibrotic lesions and mediastinum had enlarged necrotic nodes with peripheral rim enhancement. Which one of the following is the most probable diagnosis:

**Core Concept**
The patient's presentation of chronic respiratory symptoms, particularly the imaging findings of bilateral upper lobe fibrotic lesions and mediastinal lymphadenopathy, suggests a diagnosis related to chronic infection or inflammation. The presence of necrotic nodes with peripheral rim enhancement is characteristic of tuberculosis or other granulomatous diseases.

**Why the Correct Answer is Right**
The description of bilateral upper lobe fibrotic lesions is classic for pulmonary tuberculosis, a chronic infection caused by Mycobacterium tuberculosis. The infection triggers a granulomatous response, leading to the formation of caseating granulomas, which can result in fibrosis and scarring. The mediastinal lymphadenopathy with necrotic nodes and peripheral rim enhancement is also consistent with tuberculosis, as the infection can spread to the lymph nodes, causing necrosis and inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:** Sarcoidosis is a systemic granulomatous disease that can affect the lungs, but it typically presents with bilateral hilar lymphadenopathy and interstitial lung disease, rather than upper lobe fibrosis.

**Option B:** Histoplasmosis is a fungal infection that can cause pulmonary nodules and lymphadenopathy, but it typically presents with a more acute onset and is often associated with exposure to bird or bat droppings.

**Option C:** Eosinophilic pneumonia is a type of idiopathic interstitial pneumonia characterized by eosinophilic infiltration of the lung tissue, but it typically presents with a more acute onset and is often associated with asthma or other allergic conditions.

**Clinical Pearl / High-Yield Fact**
In a patient with chronic respiratory symptoms and imaging findings of upper lobe fibrosis and mediastinal lymphadenopathy, tuberculosis should be considered in the differential diagnosis, particularly if there is a history of exposure to individuals with active TB or if the patient is from a region with high TB prevalence.

**Correct Answer:** C.

✓ Correct Answer: B. Tuberculosis