The tumor originates at the superior sulcus. This portion of the lung is above the clavicle and easily palpable.

The apex of lung lies on posterior portion of upper two thoracic ribs.

Bronchial plexus and sympathetic chain are in front. Tumor at this site thus involves these structures.

Physiology

With Valsalva's and Mueller's Maneuvers the supraclavicular fossa can be made to bulge and retract corresponding to the pleural pressures during these maneuvers.

Physical Findings

Pancoast Tumor

Routine screening steps will completely miss the presence of pancoast tumor. When there is clinical suspicion, focused exam should be made.

Focused Exam

1. Palpate the supraclavicular fossa for tumor. The mass is superficial and should be palpable.
2. Loss of Kronig's Isthmus: The narrow band of resonance connecting anterior and posterior aspect of resonant chest is lost.
3. Dullness over Clavicle: The mass can extend behind clavicle.
4. Fixation of supraclavicular fossa with Valsalva's and Mueller's maneuvers. Tumor tethers the soft tissue and the supraclavicular fossa does not respond to changes in pleural pressure, unlike the opposite side.
5. Horner's Syndrome: Secondary to involvement of sympathetic chain.
6. Brachial plexus involvement along ulnar side.
7. Tenderness over posterior aspect of T1 and T2 ribs.