claw hand + interosseous muscles atrophy-->Left ulnar nerve damage, most probably due to a compression: - at lung apex--> caused by Pancoast cancer or - at the elbow --> caused by fibrosis (student elbow) or bad consolidation of a medial epicondyle fracture or by flexor carpi ulnaris - at the Guyon's canal--> caused by tumors, epidermoid cysts, etc.