In a case of juvenile xanthogranuloma in an early stage, electron microscopic examination revealed membrane activity resulting in complex interdigitations with subsequent transformation into aggregated cytoplasmic vesicles. Similar membrane complexes were encountered in multinucleated giant cells and they may be a result of endocytosis or remnants of cell membranes of fused macrophages. Other findings were “virus‐like inclusions” in histiocytes and giant cells, intracytoplasmic collagen in fibroblasts and “cross‐banded filamentous aggr