This 63-year-old woman presented with acute onset of pleuritic chest pain and shortness of breath. Her medical history was significant for left breast ductal carcinoma in situ treated four years earlier with lumpectomy, radiation and adjuvant hormonal therapy.
On initial exam, the patient was hypotensive, tachycardic and hypoxemic. Her blood work revealed metabolic acidosis and acute renal failure. Chest X-ray showed an enlarged cardiac silhouette, and a transthoracic echocardiogram revealed a very large circumferential pericardial effusion with right atrial and ventricular collapse.
The patient was taken emergently to the operating room for a pericardial window and drainage. Direct exam by the thoracic surgeon revealed smooth pericardium with no obvious lesions. Approximately 600 mL of hemorrhagic fluid was drained. The surgeon noted a fair amount of fibrinous material over the surface of the heart but no loculations. Pericardium and fluid were sent for culture and cytology, both of which were benign.
The patient’s chest pain and shortness of breath resolved shortly after surgery. Meanwhile a surveillance PET/CT examination, which was performed after surgery, showed hypermetabolic haziness in the soft tissue of the anterior chest wall and hypermetabolic soft tissue wrapping around the inferior margin of the sternum and extending deeper in the chest, abutting the anterior pericardium.
History of recent pericardial surgery was initially not available to the interpreting radiologist, and the findings were reported as suspicious of locally advanced tumor. However, the patient had improved clinically and further workup for malignancy was negative. A presumptive diagnosis of pericardial tamponade secondary to radiation pericarditis was made.
Five months later, the patient remained asymptomatic and a follow-up PET/CT demonstrated interval improvement, consistent with resolving postsurgical changes. This confirmed the benign nature of the primary PET/CT findings.
Figure 1: Representative CT, PET and fusion images demonstrate interval increase in intesity of hypermetabolism associated with metastatic disease in the rib and thoracic spine. Corresponding CT images are unchanged.
Figure 2: Axial, sagital, coronal and maximal intensity projection (MIP) PET images demonstrate significant progression of skeletal metastatic disease.
Photos courtesy of M Ghesani
In the appropriate clinical setting, the initial PET/CT results would be consistent with chest wall invasion by tumor. However, postoperative remodeling can result in an image pattern mimicking locally advanced tumor.
Pertinent history, particularly the details of recent surgery, was crucial to understanding the nature of the pathologic process, ie, remodeling vs. tumor invasion, in this particular case. The initial study report was performed without the advantage of history of recent pericardial window.
After the surgical history was available, the report was revised to indicate that the pattern might simply be due to postoperative remodeling, which was confirmed as such on follow-up PET/CT demonstrating dramatic improvement without any intervening chemotherapy or radiation therapy.
This case illustrates the overlapping pattern of post surgical repair and locally advanced tumor on PET/CT, and it highlights the importance of detailed clinical history in understanding the cause of a given image pattern.
Munir Ghesani, MD, is an Associate Clinical Professor of Radiology at Columbia University College of Physicians and Surgeons.