B64-07 A Clot Twist: Sub-massive Pulmonary Embolism Resulting From Pelvic Lymphocele Following Prostatectomy

Abstract Introduction Lymphoceles are collections of lymphatic fluid within a cavity lacking an epithelial lining, distinguishing it from a true cyst. It’s a well-recognized postoperative complication resulting from disruption of lymphatic channels, occurring after extensive pelvic surgery involving lymphadenectomy. While often asymptomatic, they may exert mass effect on adjacent pelvic neurovascular structures, leading to complications including thrombosis and neuropathy. Case Presentation A 67-year-old male with history of prostate cancer with recent prostatectomy (8/1/25), along with left lower lobe lung adenocarcinoma requiring thoracic wedge resection, lobectomy, and mediastinal lymph node dissection (8/18/25) presented with syncope. Computed tomography (CT) imaging revealed an acute sub-massive pulmonary embolism (PE) with moderate-to-large clot burden in the distal right main pulmonary artery extending into right upper and lower lobar pulmonary arteries. The patient was initiated on therapeutic heparin and underwent mechanical thrombectomy with interventional radiology (IR) (8/24/25). The patient continued to have pain and numbness in his right leg. Venous duplex ultrasound demonstrated right common femoral and femoral vein deep vein thrombosis (DVT). CT showed bilateral pelvic lymphoceles, right greater than left, new since the prostatectomy (Figure 1). IR placed a right pelvic drainage catheter, with some improvement in his symptoms (9/2/25). Discussion Lymphoceles are typically asymptomatic and a benign complication of pelvic procedures. However, in a small bunch, lymphoceles can enlarge to cause neurological and vascular complications. This case highlights a rare but clinically significant complication of pelvic lymphocele: venous thromboembolism (VTE). Reports in medical literature describing pulmonary embolism (PE) secondary to pelvic lymphocele are exceedingly scarce, with a single prior case documenting massive PE following radical retropubic prostatectomy. While this patient had other predisposing factors for hypercoagulability including malignancy and recent surgical intervention, it is reasonable that the pelvic lymphocele contributed to venous stasis and thrombosis. The clot burden was predominantly right-sided, contralateral to the side of the lobectomy, making the thoracic surgery less likely the etiology for clot formation. This is further evidenced by DVT formation in the right femoral and common femoral veins, as well as CT imaging showing an enlarged right-sided lymphocele. Treatment for lymphoceles includes conservative management, pelvic drainage catheter, or sclerotherapy. Conclusion Given the potential for serious thromboembolic complications, clinicians should maintain a high index of suspicion for lymphocele in patients with prior pelvic lymph node dissection (PLND) who present with VTE. Patients undergoing PLND should be counseled on this risk and the associated signs and symptoms of VTE. This abstract is funded by: None