Horner syndrome can be a sign of a Pancoast tumor; which malignancy is commonly associated?

• A. Brain tumor
• B. Lung cancer
• C. Breast cancer
• D. Colorectal cancer

Answer: (B)

Horner syndrome results from disruption of the sympathetic nerve pathways supplying the eye, causing ptosis, miosis, and often anhidrosis. When this syndrome is due to a tumor at the apex of the lung, known as a Pancoast tumor, it points to a mediastinal or thoracic process invading the sympathetic chain. The most common malignancy seen with apical lung tumors is lung cancer, specifically non-small cell types that arise in the lung apex. This association makes lung cancer the best choice. Brain, breast, or colorectal cancers don’t typically present with Horner syndrome from apical invasion.