A new form of sea‐blue histiocytosis associated with progressive anterior horn cell and axonal degeneration

A 15‐year‐old girl evidenced a slowly progressive central nervous system degenerative disorder. The illness had begun and progressed between ages 1 and 12 years, with ataxia, spasticity, choreoathetosis, early‐onset seizures (which later ceased), and mild retardation. At age 13 she had developed rapidly progressive generalized weakness and atrophy, indicating peripheral nervous system involvement. Laboratory investigation revealed the presence of sea‐blue histiocytes in the bone marrow without evidence of a disorder of sphingolipid metabolism or neuronal ceroid lipofuscinosis. Muscle biopsy showed large‐ and small‐group atrophy, and sural nerve biopsy demonstrated axonal degeneration. This patient's illness appears to be a hitherto undescribed form of “sea‐blue histiocytosis” associated with neurological dysfunction in children.