Incisional Seeding of Metastatic Squamous Cell Carcinoma Following Carotid Endarterectomy: An Unusual Case of an Unknown Primary Cancer Presenting as a Presumed Neck Abscess

BACKGROUND: Carotid endarterectomy (CEA) is a safe and effective procedure, with a low risk of complications when performed by experienced surgeons. Postoperative infections are particularly rare, reportedly affecting less than 1% of cases. Incisional metastases have not been described. OBJECTIVE: To describe a previously unreported complication, the incisional seeding of metastatic squamous cell carcinoma (SCC) during neck dissection, which presented and was treated as a presumed postoperative neck abscess. METHODS: Clinical records were reviewed regarding a 73-yr-old female who underwent routine CEA and presented 2 mo postoperatively with neck induration and erythema. Tissue submitted during the initial CEA was reexamined given the updated clinical history. RESULTS: Postoperatively, a complex, multi-cystic fluid collection beneath the incision was identified and percutaneously drained. Although cultures were negative, an infection was favored and antibiotic therapy initiated. The patient's symptoms worsened prompting surgical exploration, and tissue sent for pathological examination was consistent with metastatic SCC. Retrospective analysis of a lymph node excised during the initial dissection also revealed tumor deposits, indicating that the surgical site had been seeded during exposure. A primary origin was not identified. CONCLUSION: The time from initial presentation of postoperative complications to a final diagnosis of metastatic SCC was 2 mo, during which time the patient was treated as having a postoperative infection. Further investigations were consistent with diffuse and incurable metastatic disease. This report highlights the diagnostic challenges and potential avoidance strategies when dealing with rare complications following CEA.