A growing Pancoast tumor can cause Horner's syndrome due to involvement of sympathetic pathways. Which syndrome would result?

• A. Carcinoid syndrome
• B. Horner's syndrome
• C. SVC syndrome
• D. Central tumors

Answer: (B)

Damage to the sympathetic nerve pathways that run near the apex of the lung is what links apical (Pancoast) tumors to Horner's syndrome. When these sympathetic fibers to the eye and face are disrupted on one side, you see the characteristic signs: drooping of the upper eyelid because the Muller's muscle is no longer stimulated, a smaller pupil due to unopposed parasympathetic constriction, and decreased sweating on the affected side of the face. Sometimes the eye region may appear a bit sunken as well.

This makes Horner's syndrome the expected result of a growing Pancoast tumor, since the tumor commonly invades the sympathetic chain in that location. In contrast, carcinoid syndrome arises from secretion of vasoactive substances by neuroendocrine tumors and presents with flushing, diarrhea, and bronchospasm; SVC syndrome is due to obstruction of the superior vena cava causing facial and arm swelling and venous distension; and “central tumors” is not a specific clinical syndrome describing this constellation of signs.