An ultrastructural study of intranuclear rodlets in a malignant extracranial neuroepithelial neoplasm

This report describes for the first time the presence of intranuclear rodlets in a malignant extracranial neuroepithelial neoplasm. This malignant neoplasm appeared poorly differentiated by light microscopy and presented initially as a diagnostic problem. Electron microscopy revealed neoplastic cells joined by macula adherens-type junctions and containing numerous interdigitating cell processes diagnostic of a neuroepithelial neoplasm. A quantitative analysis of 500 cells revealed the presence of intranuclear rodlets in 5% of the neoplastic cells. The rodlets were composed of individual filaments that measured 7-9 nm in width. An extensive review of the literature revealed the high frequency of reported rodlets in normal neurons, normal paraneurons, neoplasms of the nervous system, and paraneuromas. The significance of this interesting structure to the physiology of the cell is discussed.