Clinical Reasoning: A 22-Year-Old Man With Multifocal Brain and Osseous Lesions.

The evaluation of patients with disseminated processes with CNS and osseous involvement is often challenging. A 22-year-old healthy man developed left-sided weakness, paresthesias, and neck pain over several weeks. On clinical examination, he was noted to have decreased right eye visual acuity, left-sided pyramidal weakness and numbness, and bilateral hyperreflexia. MRI revealed multifocal widespread abnormalities: nonenhancing lesions throughout the infratentorial brain, pituitary gland, right frontal lobe, and optic nerves, in addition to an enhancing intramedullary cervical spinal cord lesion, extensive nodular leptomeningeal enhancement of the spine, and numerous enhancing bony lesions throughout the vertebrae and iliac bones. CSF analysis was notable for normal opening pressure, protein 465 mg/dL, glucose 21 mg/dL, and normal cell count. Extensive serum and CSF analysis for infectious, inflammatory, and neoplastic etiologies was unrevealing, and the diagnosis was ultimately revealed after additional staining of tissue biopsy specimen from sacral and cerebellar biopsies. This case highlights the differential diagnoses for widely disseminated disease affecting the CNS and bones and informs pediatric and adult clinicians of important recent developments regarding this diagnostic entity.