**Core Concept:** Cutaneous tuberculosis is a manifestation of tuberculosis (TB) that affects the skin. It can occur as a result of direct extension from adjacent infected lymph nodes or as a result of hematogenous spread. Tuberculosis is caused by the bacterium Mycobacterium tuberculosis.

**Why the Correct Answer is Right:** When cutaneous tuberculosis is secondary to underlying tissue lymph node infection, it is referred to as lymphatic tuberculosis (also known as secondary cutaneous tuberculosis). In this scenario, the bacteria from the infected lymph nodes spread through the lymphatic system to the skin, causing skin lesions. The correct answer (C) describes this specific type of cutaneous tuberculosis correctly.

**Why Each Wrong Option is Incorrect:**

A. Cutaneous tuberculosis due to direct extension from adjacent infected lymph nodes would be called primary cutaneous tuberculosis. This option does not accurately represent the type of cutaneous tuberculosis associated with underlying lymph node involvement.

B. Hematogenous spread of M. tuberculosis from distant sources, such as the lungs or other organs, would result in disseminated cutaneous tuberculosis. This option does not specifically address cutaneous tuberculosis resulting from lymph node involvement.

D. Intradermal tuberculosis refers to cutaneous tuberculosis caused by direct inoculation of M. tuberculosis through a skin puncture or scratch, typically from infected individuals. This option does not address tuberculosis secondary to lymph node involvement.

**Clinical Pearl / High-Yield Fact:** Cutaneous tuberculosis should be considered in the differential diagnosis of skin lesions in endemic areas, especially in individuals with a history of possible tuberculosis exposure. Early diagnosis and treatment can prevent further spread of the infection and reduce the risk of systemic complications.