Case 65

Presentation

An 18-year-old boy with pain in the right thigh presents to your office after his general practitioner treated him for a “pulled muscle” 6 weeks ago. On examination, the right thigh is swollen and slightly red. Palpation is painful and shows increased temperature compared to the left thigh.

▪ X-Rays

Figure 65.1A

Figure 65.1B

X-Ray Report

On x-ray, an indistinct lesion of the medullary canal with mottled destruction pattern is seen. There is some reactive bone in the midportion of the lesion, some endosteal reaction, and a soft-tissue mass.

Differential Diagnosis

The differential diagnosis for an intramedullary lesion of the femur in adolescents includes osteomyelitis, lymphoma, and Ewing sarcoma. Clinical and radiological symptoms of Ewing sarcoma show a large variability. It is a “chameleon,” imitating almost all kinds of lesions of the bone. Therefore, it is most important to keep Ewing sarcoma in mind. Further imaging of the lesion should include the whole affected bone, because sometimes this tumor may grow as “skip lesions” in the compartment.

▪ MRI

Figure 65.2A

Figure 65.2B

Figure 65.2C

MRI Report

On magnetic resonance imaging (MRI), a 19 × 6.5-cm heterogenous mass is seen lateral and dorsal to the diaphyses of the femur. Enhancement is present inside the intramedullary canal. Just below the lesser trochanter, a 1-cm suspicious lesion is detected.

Recommendation

Open biopsy or needle biopsy is recommended.

Discussion

Needle biopsy is almost always sufficient to establish the diagnosis. In difficult cases, an open biopsy is strongly recommended because additional studies may be necessary, especially evaluation for chromosomal translocations. A frozen section during surgery can determine if the biopsy material is adequate in quantity and quality. Furthermore, a bone marrow biopsy can be performed under general anesthesia.

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