Ultrastructural study of intranuclear tubulo-filaments in a giant cell tumour of bone in a patient with Paget's disease.

The intranuclear tubulo-filaments appearing in giant cells were studied ultrastructurally in a giant cell tumour of bone arising in a patient with Paget's disease. Serial sections have shown the presence of invaginating nuclear membrane around these apparent intranuclear tubulo-filaments, thus segregating these structures from the nuclear substance proper. Further sectioning showed clear continuity between these tubulo-filaments and the rest of the cytoplasmic contents. It is found that these apparent intranuclear tubules represent pseudo-inclusions rather than true intranuclear inclusions.