(4.14) A Case of Isolated Paget Disease of the Sternum Mimicking Acute Coronary Syndrome

Paget disease of the bone (PDB) is characterized by excessive bone resorption followed by abnormal new bone remodeling. It is the second most common metabolic bone disorder affecting adults. The most common sites of involvement are the vertebrae, long bones, pelvis, and skull. The condition may affect single (monostotic) or multiple bones (polyostotic). We present a case of isolated Paget disease of the sternum manifesting as acute chest pain in a patient with coronary artery disease. 

Case(s) Description : A 76 year old Black male with a past medical history of end-stage renal disease, coronary artery disease, chronic obstructive pulmonary disease, cirrhosis, and stroke presented to the hospital with chest pain and shortness of breath. Physical exam revealed reproducible chest wall tenderness upon palpation. Laboratory evaluation was notable for normal troponins and elevated bone-specific alkaline phosphatase. EKG was normal sinus rhythm. Echocardiogram revealed a normal ejection fraction and no wall motion abnormalities. CT angiogram of the chest, abdomen and pelvis was notable for trabecular thickening of the sternum concerning for PDB. Further evaluation with a nuclear medicine bone scan revealed heavy uptake isolated to the sternum. The patient was treated with low dose IV pamidronate given his level of renal impairment and subsequently reported improvement in his chest pain.

Discussion : PDB is an underdiagnosed condition that is often discovered incidentally on imaging or by an elevated alkaline phosphatase level. The etiology of PDB is not fully understood; however it is thought to be related to genetic and environmental causes. There are a few documented cases of PDB confined to the sternum to date. Prior cases of PDB affecting the sternum were polyostotic and asymptomatic. This case report presents PDB of the sternum manifesting as severe chest pain. Given the patient’s comorbidities and prior myocardial infarction, it was difficult to exclude acute coronary syndrome or renal osteodystrophy. Radiographic findings were key to distinguishing PDB from renal osteodystrophy, the latter of which is characterized by thinning of cortices and trabeculae as well as diffuse bony sclerosis. This is in contrast to PDB which is characterized by cortical thickening, coarsened trabeculae, and both lytic and sclerotic lesions. Bisphosphonates are a cornerstone in the treatment of PDB. Pamidronate and calcitonin are agents that can be considered in patients who are intolerant or have contraindications to first-line bisphosphonates. This case highlights a rare presentation of monostotic Paget disease of the sternum manifesting as chest pain in a patient with multiple confounding comorbidities.