Spinal Cord and Nerve Root Involvement in Histiocytic Neoplasms

Background and ObjectivesHistiocytic neoplasms, including Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman-Destombes disease (RDD), have frequent nervous system involvement. The aim of this study was to characterize the neurologic, radiologic, and laboratory features of spinal cord and nerve root involvement in histiocytic neoplasms. MethodsWe evaluated patients with biopsy-proven ECD, LCH, or RDD seen at a tertiary referral center between January 1996 and December 2024. Patients were included if spinal MRI demonstrated spinal cord or nerve root involvement. Spinal MRI was performed for evaluation of myelopathic or radicular symptoms or as part of staging in patients with CNS involvement. We collected demographic variables, neurologic syndromes and imaging patterns, treatment characteristics, and outcomes including disability (Expanded Disability Status Scale [EDSS] score) and ambulatory status. The primary outcome was neurologic disability at nadir and last follow-up; secondary outcomes included radiographic patterns and clinical response to treatment. Data were summarized descriptively, with exploratory group comparisons performed using parametric or nonparametric tests as appropriate. ResultsAmong 415 patients with ECD (n = 183), LCH (n = 144), or RDD (n = 88), spinal cord or nerve root involvement was identified in 42 (ECD, 27; LCH, 4; RDD, 11). The median age at onset was 43.1 years (interquartile range 32.1–58.5), and 18 (43%) were female. Most cases were symptomatic (36/42, 86%), with myelopathy as the first neurologic manifestation in 26 (72%). Parenchymal infiltration predominated in the ECD group (17/27, 63%), compared with LCH (2/4, 50%) and RDD (2/11, 18%) groups (Fisher exact test across groups, p = 0.035). Root involvement was more frequent in the RDD group (8/11, 73%) than in the ECD (7/27, 26%) or LCH (1/4, 25%) group (Fisher exact test across groups, p = 0.021). The median EDSS score at nadir was 4.0; 43% required ambulatory aid or worse. After treatment, 22 of 36 symptomatic patients (61%) improved clinically and radiographically, more often in RDD (10/11, 91%) and LCH (2/3, 67%) groups than in the ECD group (10/22, 46%; Fisher exact test across groups, p = 0.022). At a median 5.8-year follow-up, 8 of 38 survivors (21%) required ambulatory assistance or were nonambulatory. DiscussionSpinal cord and nerve root involvement occurs in histiocytic neoplasms. These findings support prioritizing spinal MRI in patients with neurologic symptoms or high-risk disease features because early identification may inform diagnosis and management.