Pseudogout Mimicking Aortic Dissection: A Case Report.

Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease or pseudogout is an idiopathic articular disease that predominantly affects elderly patients. It is caused by a systemic deposition of calcium pyrophosphate (CPP) crystals in the articular and hyaline joint cartilage. The majority of cases present as chronic arthritis, but a subset of CPPD can present as rapid onset of sharp pain and joint swelling, posing a diagnostic challenge. We present a case of a 64-year-old man with a history of hypertension, urologic cancer, and gout presenting to the emergency department (ED) with a sudden-onset, severe stabbing right shoulder pain radiating to the neck and upper back. On ED arrival, he was mildly hypotensive, afebrile, diaphoretic, and uncomfortable, causing concern for aortic dissection. His exam was significant for limited shoulder range of motion; his sensation, strength, and distal pulses were intact and equal in bilateral upper extremities. His plain films showed multilevel cervical degenerative disc disease and facet arthrosis and right glenohumeral osteoarthritis without fracture or malalignment. A computed tomography (CT) angiogram was negative for vascular anomalies. Throughout his ED stay, his pain was refractory to medication, and he developed a new fever, prompting a targeted shoulder ultrasound; this revealed large glenohumeral effusion, and synovial analysis revealed CPP crystals without organism growth. This case illustrates an unusual acute CPPD attack that mimicked an aortic dissection. Emergency physicians should recognize both common and uncommon presentations for chronic disease processes in maintaining a broad differential diagnosis and delivering quick, targeted treatment.