[Viral origin of Paget's disease of bone. Contribution of electron microscopy and immunocytology of the aetiological diagnosis (author's transl)]. / L'étiologie virale de la maladie osseuse de Paget. Apport de la microscopie électronique et de l'immunocytologie.

Despite considerable research work the cause of Paget's disease of bone remains uncertain. In a study of bone tissue from 100 patients with Paget's disease electron microscopy demonstrated alterations of the cells involved in bone remodelling. Osteoblasts showed distinct signs of hyperactivity, and the fibrillar arrangement of the osteoid tissue they produce was irregular. Osteoclasts were very large with numerous nuclei, and their bone-resorption activity was abnormal. Microcylindric inclusions visible in the cytoplasma and nuclei were morphologically comparable to the nucleocapsids of measles virus observed in experimental infections or in human pathology. Immunocytology tests confirmed the presence in osteoclasts of an antigenic material belonging to the measles virus group and cross-reacting with it. The hypothesis of a viral origin for Paget's disease of bone is supported by the chronic course of the condition, the histopathology of bone tissue, the ultrastructural changes in osteoclasts and the immunological results. A virus of the measles virus group probably plays a major role in the etiology of the disease.

Towards a viral etiology for Paget's disease of bone.

The etiology of Paget's disease of bone has long remained obscure. The recent discovery in electron microscopy of specific inclusions in the cytoplasm and nuclei of osteoclasts in tissue from patients with Paget's bone disease has been the starting point of investigations into a possible viral origin. The inclusions, made up of microcylinders, described by several authors as being found only in osteoclasts in Paget's bone disease, present a close morphological analogy with nucleocapsids of paramyxovirus of the measles group. Immunocytological methods have provided a complementary approach to the problem. It has been demonstrated that the osteoclasts in Paget's bone disease contain antigenic material which reacts positively with sera containing measles antibodies. Both the morphological and the immunocytological evidence is strongly in favour of a viral etiology for Paget's bone disease.

Bone tissue in Paget's disease of bone. Ultrastructure and Immunocytology.

Ultrastructural observation in Paget's disease of bone clarify aspects of bone cells in bone tissue and demonstrate the presence of specific intranuclear inclusions composed of microcylinders in the osteoclasts. The morphologic analysis of these structures suggests an analogy with virus material of the measles group. Results obtained using indirect immunofluorescence and immunoperoxidase techniques lend further support to the hypothesis of a viral etiology in Paget's disease of bone.

Viral antigens in osteoclasts from Paget's disease of bone.

Osteoclasts from patients with Paget's disease of bone contained viral antigenic material. Ultrastructural and immunological studies suggested that measles or measles-related virus was the agent involved.

[Demonstration of measles virus antigens in osteoclasts in Paget's disease of bone]. / Mise en évidence d'antigènes viraux de rougeole dans les ostéoclastes de la maladie osseuse de Paget.

The first results of histo-immunological studies on biopsies in Paget's bone disease strongly favour the presence of antigenic material of viral origin in osteoclasts. Measles virus may play a role in the etiology of Paget's bone disease.