#00060902

H&E-stained section of a lymph node with Langerhans cell histiocytosis.  Most of the cells in this field are neoplastic Langerhans cells, some of whose nuclei contain longitudinal grooves reminiscent of ‘coffee beans.’  In the background, note small lymphocytes and scattered eosinophils.  Lymph node involvement by LCH starts in the sinuses (and a sinus pattern is still often apparent when tumor cells later infiltrate the paracortex); this recapitulates the pattern of migration and maturation of normal Langerhans cells to lymph nodes.