Pathological fracture of the tibia after bone biopsy for Erdheim-Chester disease: a case report

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized by the invasion of CD68⁺ CD163⁺ CD1a^- macrophages into organs. It is marked by a variety of symptoms and ranges from asymptomatic bone involvement to a life-threatening systemic illness. Bone involvement occurs in more than 90% of cases. Although treatment depends on lesion severity and bone localization is not fatal, such lesions may lead to severe pain and disability. Conducting a bone biopsy is important for an exact diagnosis; however, it occasionally results in pathological fractures. Herein, we report a case of a pathological fracture of the tibia following biopsy-proven bone ECD in a 78-year-old woman with a history of right knee pain.

Radiographs of both knees revealed diffusely sclerotic bone lesions in the metaphyses of the tibia and femur. Magnetic resonance imaging revealed that these lesions had hypointense signals and slightly hyperintense signals on the T1-weighted image. The sagittal fat-saturated T2-weighted image showed irregular enhancement within the lesion in the right tibia. A tibial biopsy showed infiltration of foamy CD68⁺, CD163⁺, CD1a^-, and S100^- macrophages, fibrosis of the medullary spaces, and destruction of bone trabeculae, indicating ECD. Six weeks later, the patient complained about a sharp knee pain and an inability to walk. As a radiographic examination revealed a pathological fracture, the patient was hospitalized. One week after the fracture, an operation (open reduction and internal fixation using two plates with autologous iliac bone grafting) was performed.

This case suggests that additional plate fixation immediately after a bone biopsy may be required to prevent pathological fractures. Further research about the bone strength of patients with ECD, as well as pathological fractures after tibia biopsy for ECD, needs to be investigated.