Chronic Calcaneal Osteomyelitis Due to a Retained Coral Fragment: An Unusual Cause of Heel Pain.

We report a case of calcaneal osteomyelitis caused by a retained foreign body-a coral fragment. The patient presented with nonspecific heel pain 12 years after the initial injury. MRI revealed an intraosseous lesion demonstrating the 'penumbra' sign, consistent with chronic osteomyelitis and abscess formation. CT demonstrated a foreign body embedded within the abscess cavity. Surgical exploration confirmed the presence of a coral fragment. Teaching point: Retained foreign bodies in bone can remain asymptomatic for many years, eventually presenting with signs of osteomyelitis.