A 3‐year‐old male with an extramedullary, intra‐ and extradural mass at T11‐L1

A 3-year-old boy presented to the Emergency Department with acute urinary incontinence and a 2-month history of progressive nighttime low back pain, gait disturbance, and constipation. MRI demonstrated a 3 × 1.8 × 1.2 cm, extramedullary, extra- and intradural midline mass extending from T11 to L1 level (Figure 1). The mass was isointense on both, T1- and T2-weighted images and showed moderate, focally heterogenous contrast enhancement. Postoperative course following neurosurgical total resection was uneventful. Histological examination showed a lesion with numerous foamy cells and intermingled cells with spindled morphology (Figure 2; Box 1). The lesion appeared monomorphous with focal accumulations of a few multinucleated Touton giant cells and focal infiltrates of lymphocytes, neutrophils, and eosinophils (Figure 2A). Neither pigment, nor a dense reticulin network or necrosis was present. No mitotic activity was noted. The cells were positive for CD68 (KP1; Figure 2B) and factor XIIIa (Figure 2C) but negative for CD1a, lysozyme, CD34, HMB45, Melan A/Mart1, GFAP, synaptophysin and chromogranin A. Approximately 5% of the lesion showed nuclear immunopositivity for S100. Proliferative index was varying, being as high as 5% (MIB-1/Ki67; Figure 2D). Ultrastructural analysis showed the lipidized cytoplasm of the cells as well as some cells with notched nuclei and some cholesterol clefts. No inclusion bodies such as cytoplasmic tennis racket-like bodies were identified. Molecular analysis revealed no BRAF V600E or other mutation, and no gene fusion was detected using the TruSight RNA Pan-Cancer seq panel (Illumina, USA). Access at https://isn-slidearchive.org/?col=ISN&fol=Archive&file=BPA-22-11-273.svs Juvenile xanthogranuloma. The neuroradiological differential diagnosis of our case included meningioma, ependymoma, lymphoma, and neuroblastoma. Frozen and permanent sections showed a histiocytic tumor with presence of multinucleated Touton giant cells, immunopositivity for CD68 and Factor XIIIa as well as lack of CD1a expression, lack of Birbeck granules, and lack of a BRAF V600E mutation. This pattern of pathological findings supports the diagnosis of juvenile xanthogranuloma (JXG) and excludes other histiocytosis, including Langerhans cell histiocytosis and Erdheim-Chester disease, which typically occur in older adults. JXG is the most common non-Langerhans cell histiocytosis, affects predominantly infants and young children and typically presents as solitary skin lesion [1]. In less than 5% of patients, systemic dissemination is noted, showing a mortality of 5%–10%. Isolated extracutaneous manifestations such as eye, brain, skeletal muscle, and peripheral nerve are much less common. Isolated spinal JXG is rare and may involve vertebral bodies or have an intradural/extramedullary or intra/extradural location. JXG may involve nerve roots or cauda equina. Intramedullary JXG is extremely rare. Thirteen pediatric patients with spinal JXG are reported, including the current patient, with an average age of 6.1 years and an age range of 6 months–15 years. No sex predilection is noted. Six of the spinal JXG were in an extramedullary, intradural localization, six in vertebral bodies, and one in the cauda equina. These findings in pediatric patients are not different from those in 13 reported adult patients with spinal JXG: no definite predilection of sex or location of the lesion is observed [2]. The average age of the adult group is 30.3 years with an age range of 18–67 years. Spinal JXG appears isointense to hyperintense on T1- and hyperintense T2-weighted images on MRI with homogenous or focally heterogenous contrast enhancement. JXG has been shown to harbor mutations in BRAF (p.V600E), ARAF, MAP2K1, CSF-1R, CSF-3R, KIT, ALK, MET, JAK3, and RAF1, KRAS, and NRAS as well as fusions involving BRAF, NTRK1, ALK, and RET [1, 3]. None of these molecular alterations have been detected in the current case or in any of the published cases of isolated spinal JXG that were molecularly studied for BRAF alterations (two cases were studied out of 26 in total). Complete surgical resection is the therapy of choice but dependent on the location and aggressiveness of the JXG, additional chemotherapy may be required. Complete surgical resection only was performed in 12 of the 13 solitary pediatric spinal JXG; the patients are either disease-free or stable (observation period 3 months–4.5 years). One patient received subtotal resection and neoadjuvant denosumab, a human monoclonal antibody that inhibits ligand binding to receptor activator of NF-kappa B (RANK); this patient is stable (observation period 3 years). Our patient was being followed up in outpatient clinic: at his last visit, he was demonstrating marked improvement with his ability to walk, and normal urinary function. His latest follow-up MRI did not show any residual or recurrent tumor after 3.5 years. Aziz Sagga analyzed the data, and wrote the manuscript. Vivek Mehta provided essential clinical data and reviewed the manuscript. Cynthia Hawkins provided essential material and data and reviewed the manuscript. Frank van Landeghem analyzed the data, co-wrote and reviewed the manuscript. All authors approved the final version of the manuscript. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

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