Neurohistiocytosis Presenting as Central Diabetes Insipidus and Right Exophthalmos in a 6-Year-Old Child: A Multimodal Radiological Case Report

Abstract

Neurohistiocytosis is an uncommon manifestation of histiocytic disorders in children and may involve the central nervous system, craniofacial bones, meninges, and hypothalamic-pituitary axis. Its clinical presentation is variable, and early recognition may be challenging when endocrine symptoms precede other systemic manifestations. We report the case of a 6-year-old child referred for evaluation of central diabetes insipidus associated with progressive right-sided exophthalmos. The patient had a polyuro-polydipsic syndrome, while neurological and systemic examinations were otherwise unremarkable. Initial pituitary magnetic resonance imaging demonstrated infiltrative lesions involving the skull base and cranial vault with diffuse pachymeningeal thickening and enhancement. Abdominopelvic computed tomography showed homogeneous hepatosplenomegaly without focal lesions or significant lymphadenopathy. Bone marrow aspiration revealed normal marrow elements, with no evidence of blastic proliferation or malignant infiltration. Further cerebral computed tomography demonstrated multiple osteolytic lesions of the skull base and calvarial bones, adjacent extra-axial soft-tissue thickening, pituitary stalk thickening with pituitary infiltration, bilateral irregular enhancing choroid plexus thickening, right orbital bone involvement causing grade I exophthalmos, and a right parietal dural-based mass associated with ipsilateral parietal bone osteolysis and temporopolar meningeal thickening. Taken together, these clinical and radiological findings raised strong suspicion of neurohistiocytosis with craniofacial and hypothalamic-pituitary involvement. This case emphasises the value of multimodal imaging in identifying disease extent, supporting diagnostic orientation, and guiding multidisciplinary management in paediatric patients presenting with central diabetes insipidus and orbital manifestations.