A 65-year-old miner has lost 7 kg weight within two months, has presented with cough, and blood streaked sputum. He was treated for pulmonary tuberculosis 10 years ago. He also has drooping of his left eyelid for one month. On physical examination, there is ptosis of the left eye and papillary miosis. Chest X-ray revealed round opacification in the left upper apical lobe. What is the most probable diagnosis?

**Core Concept:** Tuberculosis is a systemic bacterial infection caused by Mycobacterium tuberculosis, which primarily affects the lungs. Post-TB lymphadenitis, scars, and reactivation can lead to various manifestations like pulmonary tuberculosis, cervical lymphadenopathy, and even extrapulmonary involvement like oculomotor nerve palsy.

**Why the Correct Answer is Right:** The patient presents with a history of pulmonary tuberculosis treatment 10 years ago and has a relapse manifestation now. The clinical picture includes weight loss, cough, blood-streaked sputum, ptosis, papillary miosis, and a chest X-ray showing round opacification in the left upper apical lobe. These symptoms and findings are characteristic of a relapse of pulmonary tuberculosis.

**Why Each Wrong Option is Incorrect:**

A. The correct answer does not fit the presented symptoms and findings.

B. Although tuberculosis can cause cervical lymphadenopathy, the patient does not have this manifestation, making this option less likely.

C. Tuberculosis affecting the optic nerve is less common. The correct answer is more plausible due to the involvement of the oculomotor nerve, causing ptosis and papillary miosis.

D. Tuberculosis affecting the oculomotor nerve is less common. However, the correct answer is more plausible due to the involvement of the oculomotor nerve, causing ptosis and papillary miosis.

**Clinical Pearl:** Post-TB relapse might manifest with unusual extrapulmonary manifestations, including oculomotor nerve palsy. A high index of suspicion is necessary when considering tuberculosis as a differential diagnosis in patients with a history of previous TB treatment.

✓ Correct Answer: C. Squamous cell carcinoma