Posture-dependent pain and unilateral anhidrosis leading to diagnosis of recurrent lung cancer by positron emission tomography despite non-diagnostic CT.

Distinguishing recurrence of thoracic malignancies from chronic post-thoracotomy pain is challenging, particularly when CT is non-diagnostic. Autonomic symptoms and posture-dependent thoracic pain may provide important diagnostic clues. A male in his 50s with a history of left upper lobectomy for stage IA lung adenocarcinoma presented 3 years postsurgery with new-onset posture-dependent thoracic pain and unilateral anhidrosis on a background of persistent mild postoperative chest pain. Although CT showed no definitive findings suggestive of recurrence, the emergence of autonomic symptoms and intractable pain prompted positron emission tomography/CT (PET/CT), which revealed intense uptake in the left T1-T2 paravertebral region, leading to a diagnosis of local recurrence involving the sympathetic chain. Following concurrent chemoradiotherapy, pain improved and the patient returned to work. Posture-dependent thoracic pain with autonomic symptoms may indicate local recurrence even when CT is non-diagnostic, and PET/CT may facilitate diagnosis in such cases.