Complications of the surgical excision of encapsulated versus nonencapsulated lipomas: A retrospective analysis

ABSTRACT

BACKGROUND: Lipomas are common benign soft tissue tumors composed of mature white adipocytes, with histological features including a well-circumscribed and lobular mass covered with a thin fibrous capsule. However, lipomas that are poorly demarcated from the surrounding fat are often encountered during surgery despite a postoperative histological diagnosis. We investigated the complications associated with different types of lipomas. METHODS: This retrospective study included 119 patients who underwent lipoma excision and computed tomography (CT) imaging at our clinic between January 2011 and August 2018. We classified the lipomas as encapsulated or nonencapsulated according to the histology, CT findings, and clinical criteria. Nonencapsulated lipomas were defined as relatively heterogeneous without a distinct capsule, whereas encapsulated lipomas were homogeneous with a distinct capsule. The analyzed complications included delayed wound healing, which can cause prominent scarring, hematoma or seroma, and recurrence. RESULTS: Encapsulated and nonencapsulated lipomas were diagnosed in 89 (74.8%) and 30 (25.2%) patients, respectively. Encapsulated lipomas occurred most commonly on the head, whereas nonencapsulated lipomas occurred most commonly on the neck and trunk (P=0.000, P=0.002, and P=0.031, respectively). The Fisher exact test showed a significantly higher incidence of delayed wound healing for nonencapsulated than encapsulated lipomas (P=0.014). CONCLUSIONS: Preoperative classification of lipomas using CT imaging is important for predicting the incidence of postoperative complications. Direct excision is adequate for removing encapsulated lipomas. However, nonencapsulated lipomas might require alternative methods, such as ultrasonic liposuction, to prevent postoperative complications. Our results will help reduce the incidence of scarring by providing guidance on surgical methods.