Which order of sympathetics is associated with a Pancoast tumor?

• A. 1st order
• B. 2nd order
• C. 3rd order
• D. 4th order

Answer: (B)

A Pancoast tumor at the apex of the lung typically injures the sympathetic chain at the cervicothoracic junction, affecting the second-order neurons that run from the spinal cord to the superior cervical ganglion. The oculosympathetic pathway is a three-neuron chain: first-order neurons descend from the hypothalamus to the spinal cord, second-order neurons travel up the chain to the superior cervical ganglion, and third-order neurons proceed from there to the eye and facial sweat glands. When the second-order neurons are disrupted by a tumor at the lung apex, Horner syndrome can result, presenting as ptosis, miosis, and anhidrosis on the affected side. While any point along the pathway can produce Horner signs, the classic association with a Pancoast tumor is disruption of the second-order neurons.