Intraosseous Lipoma of the Calcaneus: A Systematic Review of Reported Cases, Imaging Characteristics, and Treatment Outcomes.

Intraosseous lipoma (IOL) of the calcaneus is a rare benign tumor composed of mature adipose tissue that may undergo fat necrosis and calcification. Because its imaging features can overlap with other radiolucent bone lesions, calcaneal IOL is sometimes misclassified and may prompt biopsy or surgical intervention for definitive diagnosis. To better characterize this entity, we conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and performed a comprehensive PubMed search using the terms "intraosseous lipoma", "calcaneus", and "heel bone". Eligible studies included case reports and series published between January 1976 and May 2024 that confirmed IOL of the calcaneus through histopathology. A total of 27 studies met criteria, representing 36 patients with a mean age of 40.3 years and a male predominance of 58.3%. Most cases were discovered incidentally or presented with mild heel pain. Imaging typically demonstrated well-defined lytic lesions with central calcification or fat attenuation, and histopathologic descriptions generally aligned with Milgram Stage I or II, though the staging system was not consistently reported. Surgical curettage was performed in 72.2% of patients, while 27.8% were managed conservatively. No malignant transformation or recurrence was reported. Calcaneal IOL should remain in the differential diagnosis for radiolucent heel lesions, and awareness of its characteristic imaging features may reduce unnecessary invasive procedures. While surgery is often chosen for symptomatic cases, conservative management is reasonable for incidental findings. Further research is needed to establish standardized diagnostic and treatment guidelines for this uncommon lesion.