Isolated neurosarcoidosis revealed by diabetes insipidus, visual loss and diplopia in a child patient: a diagnostic problem.

We report a case of 15-yr-old child that was presented with headache, polyuria, polydipsia, recent ocular motor and abducens nerve palsies and rapid visual loss. He had a long history of progressive symmetric muscular weakness predominant in the lower limb girdle. Water deprivation revealed central diabetes insipidus. Hormonal explorations demonstrated preserved pituitary function with mild hyperprolactinemia at 21.5 ng/ml (N: 2.6 to 13.1 ng/ml). Magnetic resonance imaging showed an extensive isosignal T1 and hyposignal T2 enhanced lesion infiltrating the pituitary gland, optic-chiasmal hypothalamic region, cavernous sinus, cerebrum tent and sphenoid and temporal meningeal spaces. The serum level of angiotensin converting enzyme and cerebrospinal fluid analysis were normal. No other systemic localisation was identified. Muscle biopsy objectified dystrophic changes. Genetic study identified a delT 521 mutation characteristic of Limb-girdle muscular dystrophy type 2C. Corticotherapy rapidly ameliorated the neurological symptoms. This patient was diagnosed as having neurosarcoidosis. Neurosarcoidosis is rarely reported in childhood. We discuss the problems related to diagnosis in such a situation below.