What type of tumor in the lung apex can cause Horner's syndrome and shoulder pain?

A Pancoast tumor is a type of lung cancer that occurs at the apex (top) of the lung and is often associated with specific symptoms due to its proximity to nearby structures, such as nerves and blood vessels. One well-known complication of a Pancoast tumor is Horner's syndrome, which results from the tumor invading or compressing the sympathetic nerves running along the neck and upper chest. This can cause a characteristic triad of symptoms: ptosis (drooping of the eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face.

Additionally, Pancoast tumors can lead to the infiltration of adjacent structures, resulting in shoulder pain. The pain can occur due to irritation of the brachial plexus or local invasion of the tumor into surrounding tissues, which affects the nerves responsible for sensation and movement in the shoulder area.

While other types of lung tumors, such as small cell carcinoma, carcinoid tumors, and adenocarcinoma, can cause lung-related symptoms, they are not specifically associated with the classic features of Horner's syndrome or shoulder pain in the same way that a Pancoast tumor is. Therefore, the identification of a Pancoast