This report presents the case of a child with atopic dermatitis, who developed progressive muscular weakness and hypotonia of the four limbs. The cervical spinal cord magnetic resonance imaging revealed a C(4) lesion (T(2)-weighted images); the cerebrospinal fluid findings were normal. Treatment with intravenous immunoglobulins and methylprednisolone obtained rapid clinical improvement, and approximately 1 month later the small C(4) lesion disappeared. Various diagnostic hypotheses are discussed: acute myelitis by infective agents, acute disseminated encephalomyelitis, multiphasic disseminated encephalomyelitis, multiple sclerosis, and isolated postinfective myelitis. Another hypothesis relates to atopic myelitis, a form recently described in the Japanese literature, associated with atopic dermatitis, hyperIgEemia, and high levels of specific immunoglobulin E to Dermatophagoides farinae and Dermatophagoides pteronyssinus. This diagnosis is difficult to confirm without biopsy evidence of eosinophilic inflammation.