**Core Concept**
Primary complex refers to the initial infection of the body by *Mycobacterium tuberculosis*, typically involving the lungs and hilar lymph nodes. When the infection manifests in extrapulmonary sites, especially the liver, it may indicate a congenital form of tuberculosis, where the organism is present at birth due to maternal transmission during gestation.

**Why the Correct Answer is Right**
Liver involvement in a primary complex is a rare but significant sign of congenital tuberculosis. In congenital TB, the infection occurs in utero, and the organism crosses the placenta. The liver is a common extrapulmonary site for such early infections. Unlike acquired pulmonary TB, congenital TB often presents with hepatomegaly, jaundice, and elevated liver enzymes, and the lesion is usually unilateral and not associated with typical pulmonary infiltrates. The presence of primary complex in the liver strongly suggests in utero exposure and hence congenital origin.

**Why Each Wrong Option is Incorrect**
Option A: Lungs are the most common site of primary tuberculosis, but pulmonary primary complex is typically acquired, not congenital.
Option C: Lymph node involvement (e.g., hilar or cervical) is classic for primary TB but still reflects acquired infection, not congenital.
Option D: Skin tuberculomas or cutaneous lesions are manifestations of disseminated or acquired TB, not a sign of congenital disease.

**Clinical Pearl / High-Yield Fact**
Liver involvement in a primary complex is the most specific extrapulmonary sign of congenital tuberculosis. Always consider congenital TB in infants with hepatomegaly and fever, especially when no pulmonary signs are present.

✓ Correct Answer: B. Liver