A 72-year-old man with a medical history of aortic and mitral valve prostheses, anticoagulation therapy, and a pacemaker was referred for a large lesion on the pacemaker pocket. He noticed a growing lesion several months after the implantation, which gradually enlarged over a 7-year period. Physical examination revealed a large lesion under tension without erythema, pain, or heat (Fig. 1A). Laboratory tests, including hemogram, CRP, procalcitonin, and blood cultures, were normal. A transesophageal echocardiogram ruled out pacemaker lead and prosthetic valve infections. A series of chest X-rays showed changes in the position of the pulse generator and leads over the years (Fig. 1B–E). Chest-CT scan showed a collection surrounding the device (Fig. 1F). A pocket revision drained 280 mL of a yellowish-brown odorless liquid (Fig. 1G). Histopathological analysis revealed an organized hematoma with fibrotic encapsulation showing hemosiderophages (Fig. 1H). The stains were negative for bacteria and fungi. Tissue, swab, and liquid cultures were negative. The diagnosis of a chronic expanding hematoma, also called a seroma, was made. Long-term follow-up showed a favorable evolution.
Seroma is a rare complication of the pacemaker pocket, which grows slowly over time. The etiology is related to disruption of lymphatic and vascular drainage that leads to transudative fluid collection. Its self-expanding nature is related to a dense capsule with a chronic inflammatory reaction triggered by the irritant effect of blood, which may be exacerbated by anticoagulation therapy, as in our case. The differential diagnosis includes infection, benign tumors, and malignancies. Therefore, a careful evaluation is necessary for appropriate treatment.
Informed consent: Informed consent was obtained from the patient.
Conflict of interests: None to declare.
Funding: None to declare.
