**Core Concept**
The question describes a clinical scenario consistent with tuberculous lupus pernio or more likely tuberculid, a manifestation of a cell-mediated immune response to tuberculosis. This is a type IV hypersensitivity reaction, mediated by T cells.

**Why the Correct Answer is Right**
The presence of bilateral nodular lesions on the shins and bi-lateral hilar lymphadenopathy on chest X-ray is suggestive of tuberculosis. The Mantoux test, also known as the tuberculin skin test (TST), measures the ability of the immune system to respond to the presence of Mycobacterium tuberculosis. An induration of 5 mm or more is considered a positive result, indicating latent tuberculosis infection or active disease. The skin biopsy would likely show a granulomatous reaction, characterized by the presence of epithelioid cells, lymphocytes, and sometimes Langhans giant cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the clinical scenario described. The correct answer is related to the diagnosis of tuberculosis, not leprosy.
**Option B:** This option is incorrect because the clinical presentation described does not suggest sarcoidosis. Sarcoidosis typically presents with bilateral hilar lymphadenopathy, but the skin lesions are usually erythematous and papular, not nodular.
**Option C:** This option is not consistent with the clinical scenario. The Mantoux test is a specific test for tuberculosis, and a negative result would suggest that the patient does not have latent or active tuberculosis.

**Clinical Pearl / High-Yield Fact**
In patients with a positive Mantoux test, a chest X-ray should be performed to rule out active tuberculosis, especially in those with symptoms or signs suggestive of the disease.

**Correct Answer:** C.