Light and electron microscopic examination of fine-needle aspirates in the preoperative diagnosis of osteogenic tumors: a study of 21 osteosarcomas and two osteoblastomas.

Twenty-three patients with primary osteogenic tumors, two osteoblastomas and 21 osteosarcomas, underwent fine-needle aspiration biopsy in the preoperative investigation. The cytologic features in smears were compared with the light and electron microscopic findings of resin-embedded fine-needle aspirates (16 cases) and the histopathologic findings of the surgical specimens. Cytologic smears clearly indicated a primary bone malignancy in all 20 high-malignancy osteosarcomas. In the osteoblastic osteosarcomas, the diagnosis of osteosarcoma was strongly suggested by the osteoblastic appearance of the tumor cells and the presence of an osteoid-like fibrillar matrix in 6 of 11 cases in the May-Grünwald-Giemsa-stained smears. The distinction of chondroblastic osteosarcomas from high-grade chondrosarcomas and of polymorphic osteosarcomas from malignant fibrous histiocytomas is difficult in smears. Electron microscopic examination and immunocytochemistry indicating a positivity for vimentin but not for cytokeratin helped to exclude the possibility of a carcinoma in osteoblastic osteosarcomas where the tumor cells had epithelium-like features in the smears. The resin-embedding technique of fine-needle aspirates was useful for the typing since it gave additional light microscopic information about growth pattern, structure, and matrix production, as well as ultrastructural information about cell and tissue differentiation. The osteoid-like material seen in May-Grünwald-Giemsa-stained smears could be proven to represent osteoid with varying degrees of calcification at the ultrastructural examination. The fine-needle aspiration technique, especially when used for both smears and embedding, may play an important role in the preoperative investigation of bone tumors, provided that it is used with full knowledge of the clinical and radiographic findings.

Histological study of osteoid osteoma's blood supply.

The osteoid osteoma is a painful lesion with a special predilection for the femur and tibia of young patients. Although the lesion has been described as richly innervated, its vascular supply has not been critically appraised to date in the pathology literature. To this end, we have undertaken a morphological study of 16 archival cases of osteoid osteoma, focusing primarily on the patterns of vascularization, utilizing traditional histological and immunohistochemical approaches. The study demonstrated that a prominent arterial and arteriolar blood supply was a constant finding within the various zones of soft tissues, skeletal muscle, and bone surrounding the nidus. It also showed that the caliber of the vessels underwent gradual attenuation throughout their centripetal course toward the nidus, where the vessels lost their muscularis as they merged into the capillary network of the nidus. Immunostaining with antibodies to neurofilament and S100 proteins revealed a pattern of innervation that was overall less exuberant than that described in some reports and that was virtually absent from the nidus. Taken together with data reported in the radiological literature, our findings lead us to wonder whether the osteoid osteoma may represent a response to the local stimulation of bony tissue by a primarily aberrant vasculature, a hypothesis that warrants further elucidation using state-of-the-art imaging approaches.

[Osteoid osteoma: ultrastructural aspects]. / L'osteoma osteoide: aspetti ultrastrutturali.

The authors take into consideration the ultrastructural aspects of osteoid osteoma and discuss the cellular and subcellular features of this neoplasm. Special attention is given to functional adaptability, which is specific for this type of cell, related to the degree of development of the neoformation.

[Osteoid osteoma. A scanning electron microscopic study]. / L'osteoma osteoide. Studio al microscopio elettronico a scansione.

The mineralization process of the osteoid osteoma, after removal of the organic matrix from the specimens by treatment with 6% sodium hypochlorite, has been studied by SEM. The process was characterized by calcified nodules or calcospherites, variable in size from 0,1 to 2 microns, embedded among randomly oriented collagen bundles, which delimited trabeculae of sponge primary bone. Numerous osteocytic lacunae, in various degrees of development, in the mineralizing front were present. The ultrastructural feature of the mineralization in osteoid osteoma reflected a pattern of nodular and collagenous calcification, essentially similar to primary calcification, characteristic of rapidly developing woven bone.

Intraperiosteal osteoid osteoma. A case report.

A painful intraperiosteal osteoid osteoma of the femur occurred in a 36-year-old man. Histologically, the tumor was encapsulated by the periosteum. The pain was relieved by removal of the tumor. Thirty-four months after operation, there has been no recurrence. Osteoid osteoma in this location does not appear to have been reported previously.

Scanning electron microscopy of osteoid osteoma.

We have examined the organic components of the nidus of an osteoid osteoma in 4 patients using scanning electron microscopy. Different organisation of the osteoblastic cells and of the fibrous structures of the osteoid matrix in different zones was demonstrated. These findings indicated a greater degree of immaturity in the centre, as compared with the peripheral area where the process of differentiation was more evident.

Aggressive osteoblastoma of the calcaneus.

Aggressive osteoblastoma of the left calcaneus in 29-year-old Japanese woman is reported. Her initial symptom was heel pain while walking. This was a primary calcaneal tumor, initially diagnosed as a benign osteoblastoma. After a 5-year follow-up (from the initial curettage), there was local recurrence. The histologic findings of aggressive osteoblastoma were confirmed after right lower leg amputation. The recurrent tumor was mildly aggressive to the talocalcanean joint and the retrocalcaneal area, without distant metastasis. The characteristics of the primary and recurrent tumors were examined by the radiologic, histologic, and electron microscopic procedures. Although there are questions about aggressive osteoblastoma, the authors believe that there are osteoblastic tumors of borderline malignancy between benign osteoblastoma and low-grade osteosarcoma. The current case was an example compatible with an aggressive osteoblastoma with the proposed name of Dorfman classification Group 4.

Ultrastructural study of benign osteoblastoma of the maxilla.

The ultrastructure of benign osteoblastoma of the maxilla in a 14-year-old boy was studied. Morphologically, the tumor tissue was composed of abundant osteoid of a trabecular form, and cellular and vascular connective tissue. The cellular components were osteoblasts, osteoclasts, osteocytes entrapped within the osteoid, and small perivascular cells of two types. The small cells of one type were ovoid and had a relatively large nucleus and a dark cytoplasm. The cells of the other type were elliptical and had a clear cytoplasm. The former seemed to be a preosteoblast and the latter could not be identified. The osteoblast was the predominant cell in this lesion and was characterized by the presence of abundant rough-surfaced endoplasmic reticulum and several Golgi complexes. These characteristics indicated the pronounced activity of collagenous fiber synthesis and the matrix of the osteoid tissue.

[An electron microscopic study on osteoblastoma--ultrastructure and fine localization of alkaline phosphatase].

Three cases of osteoblastoma were studied by electron microscopy. They included two cases of conventional osteoblastoma and one case of aggressive osteoblastoma. In conventional osteoblastoma, ultrastructural features and location of alkaline phosphatase activity of the osteoblast-like cell were similar to those of normal osteoblast. On the other hand, aggressive osteoblastoma cell (case 3) showed different structure from those of a normal osteoblast; the nucleus of the tumor cell showed irregular surface with a small degree of heterochromatin, and poorly developed cytoplasmic organellae. Cytochemically, alkaline phosphatase activity was noted not only on the cytoplasmic membrane, but on the abundant vesicles in the cytoplasm. From these findings we conclude that the aggressive osteoblastoma cells are more immature in morphology and show increased synthesis of alkaline phosphatase.

Osteosarcoma resembling osteoblastoma and its heterotransplantation into nude mice.

We describe a case of bone tumor in the left tenth rib that was diagnosed as a low-grade osteosarcoma resembling osteoblastoma. This diagnosis was supported by clinical, radiologic, and histologic findings. Specimens of this tumor were transplanted into nude mice, and the morphology of the transplanted tumors was examined. The transplanted tumors were similar histologically to the parent tumor. Ultrastructurally, the transplanted osteoblasts showed irregular, indented nuclei, dilated endoplasmic reticulum, and varying amounts of intercellular junctional complexes. Our transplantable tumor could be valuable as an experimental model for studies on this tumor type.

[Preliminary studies on the ultrastructure of osteoid osteoma]. / Osservazioni preliminari sull'ultrastruttura dell'osteoma-osteoide.

The ultra-structural appearance of osteoid osteoma is described. Significant features are; a well-developed endocytoplasmic reticulum, dilated cisterns in the cytoplasm of the osteroblasts, mineralized mitochondria from the cytoplasm of the osteoblasts and crystalline agglomerates on the vesicles rather than on the collagen network. The increased bone forming activity of the tissues of the osteoid osteoma is confirmed by the appearance of the osteoblastic cytoplasm. The presence of needle-like endomitochondrial crystals are further proof of enhanced osteoblastic function of the osteoid osteoma. Granular crystals appear when degenerative processes take place.

Psammous desmo-osteoblastoma. Ultrastructural and immunohistochemical evidence for an osteogenic histogenesis.

Fibro-osteo-cemental lesions of the jaw bones are a heterogeneous group of diseases which present problems in classification. Psammous desmo-osteoblastoma is one of four newly proposed entities (Makek 1983) and has until now been characterized by its light microscopic, clinical and radiological features. On electron microscopy this tumour exhibits fibroblastic (preosteoblastic), osteoblastic and osteocytic cells and a globular mineralization unlike the mineralization of the psammoma bodies. Immunohistological investigations with anti-osteonectin, a bone specific protein linking mineral to collagen, showed positive intracellular staining in all tumour cells and extracellular staining in the osteoid. The psammoma bodies were, however, not stained. These results confirm the view of the osteogenic histogenesis of psammous desmo-osteoblastoma, with an osteogenic differentiation of the tumour cells, bone formation and association of psammoma bodies which are not of bone origin. This combination of findings supports the view that psammous desmo-osteoblastoma represents a new and distinct entity occurring in desmal preformed cranio-facial bones which should be incorporated in a revised WHO-classification.

Studies on the fine structure of osteoblastoma with notes on the localization of nonspecific acid and alkaline phosphatase.

Electron microscopy of two osteoblastomas revealed the existence of three distinct types of cells in this tumor: osteoblast like, macrophage like, and multinucleated giant cells. In addition to the lysosomes, most Golgi cisternae and vesicles in the osteoblast like cells showed evidence of acid phosphatase activity. Deposits of lead phosphate indicating the site of this enzyme in the macrophage like cells were confined to the large and abundant lysosomes. Wide spread deposition of final product was noted in the cytoplasm of the multinucleated giant cells, both in conventional lysosomes, Golgi regions and special organelles probably corresponding to GERL. With regard to nonspecific alkaline phosphatase, final product indicating the location of enzyme activity was confined to the plasma membranes and associated vesicular and vacuolar structures in the osteoblast like cells. The findings suggest that the giant cells in osteoblastomas participate in lytic bone destructive and resorptive processes while osteoblast like cells appear to be osteoid and bone forming carriers of the neoplastic properties of the tumor.

The ultrastructure of conventional, parosteal, and periosteal osteosarcomas.

Twenty-seven osteosarcomas of bone were examined by electron microscopy. Eighteen cases were conventional osteosarcomas, one case was an osteosarcoma that developed in Paget's disease of bone, two cases were metastasis to the lungs of conventional osteosarcomas, five were parosteal osteosarcomas (and the recurrence of one of them), and one was periosteal osteosarcoma. In addition to the basic neoplastic cell, the osteoblast-like tumor cell, seven tumor cell types could be differentiated in varying numbers in the 27 cases examined: (1) chondroblast-like; (2) fibroblast-like; (3) histiocyte-like; (4) myofibroblast; (5) osteoclast-like; (6) malignant multinucleated osteoblast-like; and (7) atypical primitive mesenchymal cells. Moreover, endothelial cells and pericytes were also present. The tumor cells showed common neoplastic features in relation with general cell configuration and fine structures. No cytoplasmic organelle was considered to be cell-specific, and only the amount and distribution of the organelles allowed us to differentiate the above mentioned cell types. The presence of malignant appearing tumor cells with abundant and dilated cisternae of RER, in an intercellular matrix containing collagen fibers with areas of focal collections or puffs of hydroxyapatite crystals, are the most characteristic ultrastructural features of osteosarcoma. However, those features are not pathognomonic and do not allow in all cases the differential diagnosis with osteoid-osteoma and benign osteoblastoma. Fields of chondroblastic, fibroblastic, or fibrohitiocytic character are indistinguishable of chondrosarcomas, fibrosarcomas, or malignant fibrous histiocytoma of bone, respectively. The comparative study of parosteal and conventional osteosarcomas revealed a marked difference in the cell population: fibroblast-like cells and myofibroblasts were the main cell types in parosteal osteosarcoma; on the contrary, myofibroblasts were very scarce or absent in conventional osteosarcomas. This difference may correlate with the better outcome of parosteal osteosarcoma. The ultrastructural features of a periosteal osteosarcoma are reported for the first time. The tumor was comprised mostly of chondroblast-like tumor cells. However, in the more cellular peripheric areas of the neoplasm, the cells were predominantly of the fibroblast-like type and showed anaplastic features.

Ultrastructure of osteoblastoma.

The ultrastructure of three cases of osteoblastoma is described. The osteoblasts resemble normal osteoblasts with a few exceptions: irregular, indented nuclei, and occasional mitochondria with curved cristae and electron-lucent areas. The osteocytes and osteoclasts basically resemble their normal counterparts. There are also osteoprogenitor cells in different stages of maturation, some containing glycogen. The ultrastructure of an additional case histologically classified as aggressive osteoblastoma is described. It is essentially similar to the previous three cases of typical osteoblastoma. The only exception is the presence of osteoblasts with electron-lucent nuclei and less prominent organelles than the typical osteoblastoma cells have markedly indented and multilobed nuclei, dilated rough endoplasmic reticulum and lipid droplets. However, these differences from osteoblastoma cells are not pathognomonic. The final diagnosis of osteoblastic tumors rests at the light microscopy level.

Extracellular matrix vessels in human osteogenic neoplasms: an ultrastructural and enzymatic study.

The results of a study of the ultrastructural and enzymatic features of extracellular matrix vesicles in human osteogenic neoplasms are reported. Specimens from three osteosarcomas, a chondrosarcoma, and an osteoblastoma were processed for electron microscopic study and for preparation of vesicular, membrane, and cellular fractions. Electron micrographs of each lesion showed primary mineralization comprised of matrix vesicles and calcifying nodules. There was a distinct pattern of distribution of enzymatic activity among fractions from the osteosarcomas; namely that the highest values for specific activity of alkaline and pyrosphosphatases and adenosine triphosphases (ATPases) in the vesicle fractions and lowest in the cell fractions. This pattern was not consistent in fractions from the other neoplasms. The aforementioned enzymes are considered essential for the onset of mineralization. The data presented establish the role of matrix vesicles in neoplastic calcification and suggest the need for further studies into the diagnostic value of the vesicles.

Diagnostic difficulties in skeletal pathology.

In this review are discussed a small group of bone tumors that present the greatest and sometimes unresolved problems in diagnosis, not only for the clinician but also for the pathologist, even with full knowledge of the clinical and roentgenologic presentation. The following neoplastic lesions are described in detail: cartilage-forming tumors, bone-forming tumors (with special emphasis on aggressive or malignant osteoblastoma), and round-cell tumors of bone. This last group presents a special challenge to the pathologist even after histopathologic examination. Some newer, more sophisticated methods are discussed, especially those applied in the differential diagnosis of Ewing's sarcoma and tumors of neuroectodermal origin.