[Calcaneal cyst: a classical simple bone cyst?]

In the calcaneus differentiation between a solitary cyst and intraosseus lipoma is difficult. Radiologists frequently diagnose an intraosseus lipoma, whereas histology shows the classical signs of a solitary bone cyst. We present 12 cases of a solitary cyst of the calcaneus.

Between 1993 and 2001 we operated on 12 patients (8 men, 4 women, median age 28 +/- 14 years) with calcaneal cysts. 9 patients received a curretage and an autologous, one patient a homologous, one patient a mixed autologous-homologous bone-grafting and one patient only a curretage (due to the small diameter of the cyst) of their cysts.

No case revealed the histological picture of a fatty formation, which appears to be typical for an intraosseus lipoma. All of the microscopic findings resembled the characteristics seen in cysts of the long bones. A pathological fracture has not been observed.

The histologically confirmed calcaneal cysts showed the radiological signs that are supposed to be typical for an intraosseous lipoma. It cannot be decided whether the histologically diagnosed calcaneal lipomas described by others can be interpreted as fatty degeneration of a calcaneal cyst, or whether fatty areas of the bone marrow have given a wrong impression. Since the literature only describes single isolated cases of a pathological fracture of the calcaneal cyst or lipoma, asymptomatic patients should be treated non-operatively.