Table 3

Clinical and pathological observations that support or controvert the malignant origin of pulmonary Langerhans' cell histiocytosis (LCH)

Observations against a malignant origin Observations compatible with a malignant origin
 Occurs almost only in heavy cigarette smokersExistence of diffuse (aggressive) forms of
 Isolated pulmonary involvement in most casesLCH
 Spontaneous remission frequentRecurrence after transplantation
Pathological findings
 Bronchocentric distribution of lesionsLC in pulmonary LCH are clonal
 Virtual absence of LC in end stage lesions
 Cellular atypia rare
 Low rate of LC proliferation
  • LC = Langerhans' cells.