Ultrastructural observation of Birbeck granules in 8 cases of Langerhans cell histiocytosis

Objective To study the ultrastructural features of Langerhans cell(LC), especially Birbeck granules in Langerhans cell histiocytosis(LCH) and provide some ultrastructural evidence to clarify the origin, function and stereoscopic structure of Birbeck granules. Methods Pathologic tissues of 8 LCH patients were treated with routine transmission electron microscope(TEM)procedures, fixture, dehydration, permeation, embedding, polymerization, ultramicrocut, staining and examined by TEM. Results Under the TEM, 8 cases of LCH revealed typical LC cell, and LC cell in 6 cases revealed typical rod, tennnis-racquet like Birbeck granules.Some double membrane structures revealed irregular shape, sometimes accompanied with vacuole-like structure.Most of Birbeck granules locate inside the cytoplasmic membrane, in continuity with the cell membrane.There was Birbeck granule-like structure outside the cytoplasmic membrane in one case of multisystem LCH. Conclusions The ultrastructure of Birbeck granules could be various and irregular.The irregular Birbeck granule-like structure can also be useful for the diagnosis of LCH.Birbeck granules may arise from the cell membrane.The stereoscopic structure of Birbeck granules could be irregular. Key words: Langerhans cell histiocytosis; Birbeck granules; Ultrastructure; Electron microscope