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A case of benign osteoblastoma of the parietal bone is presented. Attention is drawn first to the rarity of this tumor and second to the fact that the radiological and histopathological features of the tumor reported here lead us to suspect the presence of regressive features in its evolution.
We present a case with a full-thickness bony defect in the frontal area. It was corrected successfully by a free bone graft to the outer table from the parieto-occipital area, partly covered by a flap of periosteum from the same area.
Partial removal of the frontal or parietal bone increased concentrations of mRNAs coding for preprocholecystokinin and preprosomatostatin in rat parietotemporal cortex by more than 170 and 67%, respectively, when measured 3 days after the operation. The increases were independent of the anaesthetic agent used during the operation and were transient with a maximum usually observed 3 days after the operation. They occurred not only in areas close to or under the removed bone part, but also in more distant areas. Thus, removal of the frontal bone also enhanced levels of preprocholecystokinin- and preprosomatostatin-mRNA in the parietotemporal and occipital cortex. mRNA concentrations were increased in the inner as well as outer layers of the cortex. The possible experimental and pathophysiological implications of the observed changes in gene expression of both neuropeptides in neocortical neurons are discussed.
A case of an infant with an asymmetrical head is presented. On clinical assessment the patient displayed features of deformational plagiocephaly. With the aid of three-dimensional CT imaging of the skull, a bipartite parietal bone was diagnosed. The prevalence and possible aetiology of a bipartite parietal bone is discussed as well as a brief overview of the common causes of plagiocephaly.
Between years 1996 and 1997, pedunculated parietal bone graft for facial reconstruction after tumor excision was used in 8 patients. The defects comprised one side of maxilla with the orbit bottom, zygomatic bone and the orbit bottom, mandibular ramus, and the whole mandible: in 4, 1, 2, and 1 patient respectively. The reconstruction was done directly after tumor excision in 6 patients and later on in the other 2. The grafts were of full thickness in 6 and of outer table in 2. Functional and cosmetic effects were considered satisfactory in 6 patients. The whole mandible reconstruction ended up with a failure due to infection and tumor recurrence.
The embryologic origin of the parietal bone is membranous bone. Experimentally, membranous bone grafts, maintain its original size, structure with good osteo-integration contrary to endochondral bone autografted (ilium, rib or tibia). The morbidity of skull bone grafts is much less than other donor site of bone. In our study, between 1988 and 1992, autogenous split calvarial bone grafts were used in maxillo-facial reconstruction of seventy-one patients. We observed no major complication. Patient followup has been from 2 to 6 years and results are better than endochondral grafts (iliac crest, ribs, tibia). Parietal grafts bone have been used in the following case: nasal reconstruction, rehabilitation of defects in the floor of the orbit, maxilla grafts, correction of frontal depression and mandibular reconstruction.
Ipriflavone, a synthetic isoflavone-derived flavonoid, was shown to have inhibitory effect on bone resorption. In order to study its mechanism of action directly on bone, 46 female Wistar rats were divided into six groups and medicated orally for 25 days as follows: groups 1 and 2 were given 1% carboxymethylcellulose solution (vehicle), groups 3, 4, 5, and 6 were administered ipriflavone at doses of 0.178, 0.356, 0.712, and 1.424 mmol/kg/day (suspended in vehicle), respectively. On the 22nd day, parathyroid glands, taken from donor rats, were transplanted in contact with the outer surface of the periosteum of both the right and the left parietal bones of rats from groups 2, 3, 4, 5, and 6. The group 1 rats underwent sham operation. Bone histomorphometry, performed on the ectocranial periosteum of parietal bones, showed that absolute erosion boundary, absolute eroded area, absolute erosion depth, number of tartrate-resistant acid phosphatase (TRAP)-positive polynucleated osteoclasts, and number of TRAP-positive mononucleated cells decreased in ipriflavone-treated rats compared with group 2 rats. The reduction was roughly proportional to the increase of drug dosage and reached statistical significance in rats of groups 5 and 6. The same parameters were extremely low in group 1 rats. Mineral apposition rate did not differ in any of the groups. Significant increase of serum calcium and significant decrease of serum phosphate were found in group 2 rats compared with group 1 rats, whereas no differences from controls were detected in ipriflavone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
A case of chronic diploic hematoma of the parietal bone is reported. This lesion is considered to have developed over several years following minor head trauma. Clinical, radiological, and pathological findings of this rare lesion are described. To the authors' knowledge, this is the first reported case of such an uncommon traumatic lesion with a description of its appearance on magnetic resonance imaging. Also discussed are the possible pathogenetic mechanisms involved in the slowly progressive enlargement of the lesion.
A study was undertaken to study the regeneration potential of surgically created parietal bone defects in newborn and fully grown rabbits. The results indicated that regeneration is greater in the newborn rabbits, especially if the periosteum and dura are preserved.
Malignant fibrous histiocytomas (MFHs) are mesenchymal tumors, usually arising in soft tissue of the extremities and are remarkably resistant to radiation and chemotherapy. A 45-year-old female presented with a rare case of MFH originating in the cranial bone manifesting as a lump in the left parietal region with no neurological abnormality. Neuroimaging revealed the presence of an osteolytic tumor in the left parietal bone invading into muscle and subdural region, penetrating through the dura. Selective external carotid angiography disclosed a marked tumor stain. Examination of the whole body excluded neoplastic disease elsewhere. The patient was treated by surgical excision, radiation, and two courses of multi-drug chemotherapy using cyclophosphamide, doxorubicin, vincristine, and prednisolone. Since there is no established treatment against this malignancy, a longer follow-up is necessary to determine whether cure has been achieved.
Histomorphological studies carried out during 1 month after autotransplantation of the parietal bone into a facial skull defect showed necrosis of osteocytes, contents of bone marrow spaces, and feeding channels in the transplanted autobone. During this period and later loose connective tissue grows into them. As a result of resorption of osseous matter, new bone cavities are formed and the lumina of feeding channels are dilated. Simultaneously a new bone substance, containing viable osteocytes, appears on their walls. Gradually the autobone graft is replaced by newly formed bone tissue.
Complete agenesis of both parietal bones was found as a single anomaly in an otherwise healthy boy. The defect in the cranial vault was restored with performed methyl methacrylate onlay plates.
We examined the osteogenesis process in transforming growth factor beta 1 (TGF-beta 1)-treated neonatal and adult rats, aiming to investigate the age difference in the effect of TGF-beta 1 on mesenchymal cell differentiation. Recombinant human (rh) TGF-beta 1 (20 and 200 ng) was injected onto the outer periostea of the right side of the parietal bone of each rat once a day for 1-12 days starting at the age of either 1 day or 12 weeks. On the day after the final injection, the calvaria was excised and evaluated histologically. In the neonates, the 12-day treatment with rhTGF-beta 1 increased the number of osteoprogenitor cells, resulting in intramembranous ossification. In the adult rats, rhTGF-beta 1 induced differentiation of chondrocytes. Cartilage masses were surrounded by mesenchymal cells, which would differentiate into chondrocytes. The cartilage matrix was partially calcified, with chondrocytes buried therein. In the calcified matrix, marrow cavities containing some multinuclear osteoclasts were formed. These findings indicate that rhTGF-beta 1 stimulated the differentiation of mesenchymal cells into chondrocytes and produced the cartilaginous matrix. rhTGF-beta 1 induced intramembranous ossification of the parietal bone in neonatal rats, and it induced enchondral ossification in adults. This result suggests that the different responses of mesenchymal cells in the periosteum to rhTGF-beta 1 may depend on the age of the animals used: namely, they may reflect the respective osteogenic stages of modeling and remodeling.
The findings in a newborn male with agenesis of parietal bones, gracile long bones, and hypoplasia of the spleen are presented. Although parietal agenesis is unique, the findings are compatible with 18 previously reported cases characterized by cranial hypomineralization, Kleeblatschädel, gracile bones, and splenic aplasia/hypoplasia, the nomenclature for which has been descriptive: gracile bone disorders, "osteocraniostenosis," "osteocraniosplenic syndrome." The term "osteocraniostenosis" may be inappropriate in that craniostenosis has been infrequently reported, a feature also of importance with respect to the pathogenesis of the Kleeblatschädel. The group likely reflects heterogeneous etiology and pathogenesis. Precedent, however, including animal models, justifies consideration of genetic aberrations, in particular, mutations in homeobox genes. (c) 2006 Wiley-Liss, Inc.
An immunocytochemical method using an antibody against 5-bromo-2'-deoxyuridine has been applied to the study of the kinetics of osteoclast nuclei on intact mouse parietal bones. Osteoclasts containing tartrate-resistant acid phosphatase show nuclei that are positive for the thymidine analogue within 24 hours of injection into four-day old mice. Labelled osteoclast nuclei decline in number with a half-life of 1.3 days, compatible with a random mechanism of cell death rather than a fixed lifespan. This is shorter than has previously been reported and the possible reasons for this are suggested. The main advantages compared with autoradiography are the shortened processing time and the large number of osteoclasts that can be examined per parietal bone.
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PURPOSE: This study evaluated the effect of insulin on fracture in fetal rat intramembranous bone using an organ culture system in which bone mineralizes in vitro. MATERIALS AND METHODS: Twenty-day-old fetal rat parietal bones were fractured parallel to the frontal plane and cultured in a serum-free medium with or without insulin for 4 to 12 days. They were then processed for light microscopy. RESULTS: In the specimens not treated with insulin, bony bridges were observed in less than 10% on day 4 and 8, and only 45% on day 12. In bones treated with insulin at 10(-6) mol/L, bony bridges were observed in 73% on day 4 and 100% on day 8 and 12. No callus or cartilage formation was observed during the wound repair process, indicating that intramembranous ossification occurred. CONCLUSION: These findings suggest that insulin has a direct effect on bone cells, which enhances the healing of fractures in intramembranous bone.
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