Background: Neurofibromatosis type 1 (NF-1) is the most common of the neurocutaneous disorders. It leads to significant orthopedic complications and spinal deformities. Scalloping in NF-1 may be caused by weakness of the mesodermal dysplasia, which develops through the inherited mutation of chromosome 17. Aneurysmal bone cysts (ABCs) are rare, rapidly expanding, locally destructive, and often misdiagnosed lesions. Assessment of sacrum scalloping in NF-1 caused by aneurysmal bone cyst is described.
Case description: A 15-year-old male was a patient with NF-1. He presented with cramping pain of the left soleus muscle, which had developed over the previous 3 months. The magnetic resonance imaging of the lumbar-sacrum region revealed a well-circumscribed multiloculated lesion located in the dorsal sacrum region and causing posterior vertebral scalloping and compression of nerve roots. The preoperative clinical suspicion was of a neurofibroma, a giant cell granuloma, or a lymphoma. However, the histopathologic diagnosis was consistent with ABC of the sacrum. This differed from our preoperative suspicion.
Conclusion: The etiology of ABCs is still unknown. Some researchers have described ABCs with chromosomal abnormalities of 16q22 and/or 17p13. This is consistent with NF-1, which develops through the inherited mutation of chromosome 17. Therefore, mutation of the chromosome may play an important role in the development of NF-1 and ABCs. Adequate diagnosis is necessary before treatment or biopsy of ABCs because bleeding may occur during operation or biopsy. Surgery is the treatment of choice for most ABCs. Adjuvant megavoltage radiotherapy is indicated for patients with recurrent tumors and whose tumors are inoperable.