Bilateral Upper and Lower Limb Complex Regional Pain Syndrome (CRPS) in a Lung Cancer Survivor: Diagnostic and Interventional Challenges in the Setting of Radiculopathy and Prior Radiotherapy.

We present the case of a 64-year-old man with an unusual and diagnostically challenging presentation of Complex Regional Pain Syndrome (CRPS) Type I involving both the left upper and lower extremities. His illness was precipitated by an on-the-job injury and was further complicated by a prior history of adenocarcinoma of the lung treated with radiation, resulting in severe left upper extremity (LUE) weakness along with cervical and lumbar radiculopathy. The overlapping clinical picture of CRPS, lumbar and cervical radiculopathy, and presumed radiation-induced brachial plexopathy (RIBP) posed a significant diagnostic challenge. This case highlights the usefulness of applying systematic diagnostic criteria, such as the Budapest Criteria, in diagnosing CRPS, particularly in the setting of coexisting neurologic pathology. It further underscores the importance of early recognition, multidisciplinary evaluation, and individualized treatment planning in patients with non-classical presentations of CRPS, especially within the post-cancer cohort.