Ipsilateral Hip Bone Mineral Density Loss in Lipomatosis of the Sciatic Nerve With Lumbosacral Plexus Involvement: A Hypothesis-Generating Case Series.

Abstract

Lipomatosis of nerve (LN) is a rare fibroadipose overgrowth disorder associated with nerve-territory soft-tissue and skeletal hypertrophy. Although osseous enlargement is well recognized, its potential effects on bone mineral density (BMD) have not been described. We describe a series of patients with lipomatosis of the sciatic nerve with lumbosacral plexus involvement to assess for ipsilateral, hip-specific BMD differences. Institutional cases of lipomatosis of the sciatic nerve with lumbosacral plexus involvement were retrospectively reviewed. Patients who had undergone hip dual-energy x-ray absorptiometry (DEXA) as part of clinically indicated care were identified. Demographic, clinical, and side-to-side hip BMD data were analyzed descriptively. Twelve patients with lipomatosis of the sciatic nerve were identified (6 women, 6 men). Hip DEXA was available in three patients (25%), all women with lumbosacral plexus involvement, neuropathy, and nerve-territory overgrowth. All three demonstrated lower BMD at the ipsilateral hip, with side-to-side reductions ranging from 13% to 23% compared with the contralateral side. In this descriptive series, patients with lipomatosis of the sciatic nerve with lumbosacral plexus involvement demonstrated ipsilateral hip BMD reduction. These findings are hypothesis-generating and suggest a potential association between LN and region-specific bone loss. Further studies are required to determine prevalence, mechanism, and clinical significance.