[Langerhans cell histiocytosis of the dens axis]

Langerhans cell histiocytosis, formerly known as histiocytosis X, is characterised by clonal proliferation of pathologic cells resembling Langerhans cells. Langerhans cell histiocytosis is commonly localised in the bones of the skull or in the skin; however, a great variety of foci has been described.

A general practitioner referred a 25-year-old man to the neurologist because of progressive pain in the neck that had arisen spontaneously. The pain had become so severe over a period of 3 weeks that he had had to support his head with both hands to ease it. Chiropractic treatment had resulted in a worsening of the symptoms. On physical examination, two pathologically enlarged lymph nodes were palpable on the left side of the neck. CT, MRI and PET scans revealed an osteolytic lesion at the site of the dens axis (C2). Immunohistochemistry of the lymph node demonstrated positive staining for CD1a and S100, characteristic of Langerhans cell histiocytosis. The patient was treated with chemotherapy and osteosynthesis of the C1-C2-C3 vertebrae; he was able to return to work after 9 months.

Langerhans cell histiocytosis is an extremely rare condition; its diagnosis is often missed or made at a later time. The golden diagnostic standard is histopathological analysis of the abnormality. The condition's prognosis is related to its extent. Its localisation in the dens axis has not been previously described.