A radiological diagnostic approach to tumours and tumour-like lesions of the calcaneus

Abstract

Objective: The calcaneus is a rare location for the development of primary bone tumours. The purpose of the study is to review the imaging findings in a cohort of patients presenting with tumours and tumour-like lesions of the calcaneus and to develop a more structured approach to the diagnosis of calcaneal lesions.

Methods: A retrospective study with a collection of 167 cases of calcaneal tumours and tumour-like lesions from our tertiary orthopaedic oncology institution over a period of 13 years. Cases were reviewed by two consultant musculoskeletal radiologists and the location of the lesion within the calcaneus and demographics of the patient were noted for each case. A diagnostic algorithm, which is based on patient age and tumour location, was then extrapolated.

Results: Out of the 167 cases, we identified 24 different calcaneal pathologies which included both tumours and tumour-like lesions. The most common being simple bone cysts (18.3% of cases) and intra-osseous lipoma (15% of cases) sited in the diaphyseal equivalent of the calcaneus. A diagnostic algorithm was formulated, which describes the most common location of the different pathologies including both benign and malignant pathologies, subdivided by age.

Conclusion: Our algorithm should help the radiologist narrow down the differential diagnosis when evaluating calcaneal lesions.

Advances in knowledge: This article provides a radiological approach to calcaneal lesions.

Figure 1.

Schematic diagram of the calcaneus demonstrating the three epiphyseal equivalent : posterior (P), superior (S), anterior (S), diaphysis (D) and anterior (a) and posterior (p) metaphyses (M)

Figure 2.

Diagnostic flow chart to aid assessment of calcaneal lesions in patients < 20 years of age. AE, Anterior epiphyseal equivalent; D, Diaphyseal; PE, Posterior epiphyseal equivalent; SE, Superior epiphyseal equivalent.

Figure 3.

Diagnostic flow chart to aid assessment of calcaneal lesions in patients 20–40 years of age. AE, Anterior epiphyseal equivalent; D, Diaphyseal; PE, Posterior epiphyseal equivalent; SE, Superior epiphyseal equivalent.

Figure 4.

Diagnostic flow chart to aid assessment of calcaneal lesions in patients > 40 years of age. AE, Anterior epiphyseal equivalent; D, Diaphyseal; PE, Posterior epiphyseal equivalent; SE, Superior epiphyseal equivalent.

Figure 5.

Clustered bar chart demonstrating the 24 different calcaneal pathologies identified in descending frequency.

Figure 6.

Simple bone cyst. Typical site and appearances for this benign lesion. Lateral radiograph (Image a) shows a lytic diaphyseal lesion and Sag STIR (Image b) demonstrates a high T2W simple bone cyst.

Figure 7.

X-ray (a) demonstrating mixed lytic/sclerotic change in the posterior epiphyseal equivalent. This is confirmed on sagittal CT reconstructions (b) and STIR sagittal MRI (c), which depicts marked bony oedema involving the posterior metaphysis and surrounding soft tissues. These are features of osteomyelitis and this occurs most commonly in the posterior epiphyseal equivalent

Figure 8.

Lateral X-ray of the calcaneum shows marked destruction (a) of the calcaneum and distal tibia (white arrow). Sagittal T1 MR image shows malignant infiltration with low T1 signal involving the whole of the calcaneum with an epicentre in the posterior meta-epiphyseal equivalent. Low T1 focus also seen in the distal tibia (white arrow). This was diffuse metastases from renal carcinoma.

Figure 9.

Radiographic and CT features of osteosarcoma in the calcaneus. Appearances are of an aggressive lesion involving the whole of the calcaneal diaphysis with extra-osseous extension.

Figure 10.

Sagittal STIR MR image depicts typical appearance of a chondroid lesion with aggressive features. High signal on water sensitive sequences with chondroid matrix is typical of a chondroid tumour. The aggressive appearance is in keeping with biopsy proven chondrosarcoma

Figure 11.

Radiographic and MRI features of Ewing’s sarcoma in the calcaneum. 5.4% of the 164 calcaneal lesions in our cohort were Ewing’s sarcoma. The majority of cases were centred around the posterior epiphyseal equivalent as shown.