Calcaneal cysts and lipomas: a common pathogenesis?

Abstract

Calcaneal cysts and lipomas are relatively rare, benign bone lesions. They are similar in many ways, including in their location and radiological appearance, but their content differs. Cysts contain fluid whereas lipomas contain fat, although some lesions may exhibit a mixed content. The pathogenesis of the two entities is the subject of controversy. The theory that calcaneal cysts may result from lipomatous necrosis has been widely suggested in the literature, but no such progression has ever been shown. The contrary hypothesis has also been considered, i.e., that the content of regressing cysts may be replaced by fatty marrow, leading to a lipoma-like appearance. This second theory is based on indirect arguments, notably that lipomas have a similar location to intraosseous calcaneal ganglion cysts that arise from the subtalar joint and that patients are older in cases of calcaneus lipomas than in cases of calcaneus cysts. We offer an additional argument in favor of this hypothesis. We present an original observation of a calcaneal cyst incidentally discovered in a 15-year-old male whose spontaneous evolution 3 and 7 years later revealed progressive replacement of its fluid content by fat.

Intraosseous lipomas originating from simple bone cysts

“…While we completely agree with this conclusion, we are surprised that the authors write that the cases they described are the first definitive proof that at least some (and possibly all) SBCs heal to assume the imaging characteristics of intraosseous lipoma. In fact, in a paper published in Skeletal Radiology in 2017, we had already reported a presumed calcaneal bone cyst evolving at follow-up imaging towards a calcaneal lipoma [2]. A similar case was published later by Powell et al [3].…”

Imaging Findings of Calcaneal Cyst and Lipoma: Can Intraosseous Cyst Changes Into Lipoma With Advancing Age?

“…1 Intraosseous lipomas of the calcaneus, which are composed of cavities filled with fatty tissue, are also benign osseous lesions originating from proliferating mature lipocytes. 1 The calcaneus is the most common location of intraosseous lipomas. Calcaneal lipomas usually occur between 30 and 60 years of age.…”

https://researchopenworld.com/bone-and-soft-tissue-tumours-of-the-foot-and-ankle/#

“…There is a peculiar trabecular-poor area within the calcaneal body (stress-shielded region) which often develops intraosseous lipomas (vicarious lipoma). Those lipomas in turn may render liquid or they become calcified due to fat cell necrosis [8].…”