Case Presentation
A 36-year-old male, a military person, presented with mild pain and swelling over the left ankle region for two days following the history of mechanical trauma sustained while running. Clinical examination revealed mild tenderness in the lateral aspect of the ankle, without evidence of a palpable mass. Ankle movements were normal except for mild pain on inversion. He was a social drinker and non-smoker. He had no history of chronic medical conditions and was also not under any long-term medications. He was initially managed with oral analgesics and advised to refrain from involving in strenuous exercises like running.
A plain radiograph of the left ankle was ordered which showed a well-defined, radiolucent bone lesion of size measuring about 24 x 28 mm within the anterior part of the calcaneum, with central radiopaque area of calcification called as Cockade sign as shown in Figure 1. Subsequently, a CT scan of the left ankle was performed to characterize the lesion, revealing a well-defined lytic lesion in the calcaneal neck measuring 25 x 29 x 34 mm with a smooth sclerotic margin and narrow transition zone. It showed areas of low attenuation equivalent to fat density (-60 Hounsfield units) and coarse calcification in the center. The inferior cortex of the calcaneum was thinned out without any cortical break as shown in Figure 2a and 2b. A diagnosis of intraosseous lipoma (stage 3) of the left calcaneum was thus made.