16 August 2022
: Case report 
Histiocytic Disorder Mimicking a Brain Tumor: A Report of 2 Rare Cases
Challenging differential diagnosis, Diagnostic / therapeutic accidents, Management of emergency care, Rare disease
Frances Xiuyan Feng12BCEF, Negin Farsi
2BC, Min Dai2BC, Areli K. Cuevas-Ocampo2AD, Diana M. Veillon2ADE, James D. Cotelingam2ADE*
DOI: 10.12659/AJCR.935885
Am J Case Rep 2022; 23:e935885
Table 2. Comparison of CNS involvement of three most common histiocytic lesions.
| LCD | ECD | RDD | |
|---|---|---|---|
| Epidemiology | Mostly occur in childhood and male predominant | Mean patient age at diagnosis is 55–60 year, with male predilection. Pediatric cases are reported as well | Most cases occur in adolescent and young adult with African American predilection |
| Most common location of CNS involvement | Hypothalamic-pituitary axis | Hypothalamic-pituitary axis and meningeal involvement, cranial lesion | Dural based lesions |
| Clinical features | Diabetes insipidus followed cranial involvement. Skull and mandibular involvement are common | Diabetic insipidus and severe neurodegenerative cerebellar disease | Mimic meningioma |
| Morphological features | Neoplastic histocytes containing kidney shaped nuclei with grooves and reactive eosinophils in the background. Birbeck granules are typical ultrastructural features | Neoplastic foamy histocytes and Touton cells. Reactive inflammatory and fibrosis may present | Lesional histocytes with emperipolesis and reactive abundant mature plasma cells. Dutcher bodies may be prominent |
| Immunophenotype | S100+, CD1a+, Langerin +; CD68+ | CD68+, S100-; CD1a-, Langerin- | CD68+; S100+, CD1a-, Langerin- |
| Genetic profiles | ~50% cases demonstrate mutation | ~50% cases demonstrate | No evidence of clonality |