Lipomas Eroding Adjacent Bone: Report of Three Cases

Lipomas are common benign masses of variable size that may be found in a variety of superficial and deep tissues. As a benign growth, lipomas do not typically invade into adjacent structures such as bone. However, when a lipoma has grown large enough, several studies have noted bony erosion in adjacent bony structures. In this series of cases, we report three instances where a large lipoma caused adjacent bony erosion and describe the respective imaging findings.

A 57-year-old woman had a left gluteal mass eroding the outer surface of the ilium; a 68-year-old man with a recurrent right buttock lipoma demonstrated similar erosion of the posterior ilium; and a 79-year-old woman had a multilobulated lipoma extending through the scapula from posterior to anterior. In all cases, imaging revealed well-defined, homogenous lipomatous masses with adjacent osseous scalloping best visualized on computed tomography. Histopathology confirmed benign lipomatous tumors with fat necrosis and no evidence of malignancy.

Large, deep lipomas, though benign, can rarely cause pressure-induced erosions of adjacent bony structures. Recognizing this atypical presentation is crucial to avoid misdiagnosis as a malignant tumor and to guide appropriate surgical management.