Chromosome aberrations in fibrous dysplasia

Jawbone fibrous dysplasia: retrospective evaluation in a cases series surgically treated and short review of the literature

BACKGROUND AND AIM OF THE WORK

Fibrous dysplasia is a fibro-osseous osteopathy in which the normal bone architecture is replaced by fibrous tissue and non-functional trabeculae-like osseous structures. In head and neck area monostotic or polyostotic lesions cause a progressively expanding destructive bone swelling producing cosmetic deformities and functional impairments. The aim of this article is to present a retrospective review of a clinical case series with pathologically confirmed jawbone fibrous dysplasia for over an 8-year-period.

MATERIAL AND METHODS

Clinical presentation and radiographic features of fibrous dysplasia affecting the jawbone skeletal area, surgical procedures performed including the reconstructive methods employed and clinical outcomes were analysed for each patient.

RESULTS

Seven cases were classified as having monostotic fibrous dysplasia while the others four cases were classified as having polyostotic form. The mandible was most commonly involved. The most common presenting features included marked facial deformity, intraoral bulging, malocclusion and dental alterations. Aesthetic and/or functional impairments were the major indications for surgical treatment in all the patients of this series. Six patients underwent bone remodelling while in the remaining cases subtotal or total resection was performed. Bone reconstruction by means of autologous free bone grafts or revascularized free bone flaps was made in three cases.

CONCLUSION

The choice of the tailored therapeutic approach should be evaluated according the patient's age, rate of growth, anatomic location, type of involvement and the presence or not of functional disturbances and cosmetic alterations. Surgery remains the best therapeutic option.

Fibrous dysplasia

Fibrous dysplasia is an uncommon bone disease. The diagnosis is usually not difficult, given the symptoms, radiology, and histology. The gene involved is the α subunit of the G-protein receptor. Recent innovation in molecular pathology has helped us understand the mechanism of disease pathogenesis. The treatment of fibrous dysplasia is limited to maintenance of maximum bone density. Surgical reinforcement is used to treat bowing deformities and fractures as they occur. Malignant transformation of fibrous dysplasia is rare. Currently, there is no therapy for preventing the disease from advancing or for malignant transformation.

Advances in the identification of molecular markers for bone neoplasia

IMPORTANCE OF THE FIELD

Bone tumors represent a heterogeneous and poorly understood group of neoplasms affecting patients of all ages. This review is intended to highlight recent advances in the identification of diagnostically relevant molecular biomarkers.

AREAS COVERED IN THIS REVIEW

This review offers a summary of basic techniques in molecular pathology. In the case of primary bone tumors with diagnostically applicable molecular markers, an overview of the tumor is provided incorporating the germane background and advances in the identification of molecular markers.

WHAT THE READER WILL GAIN

The reader will gain an understanding of the techniques governing the discovery of biomarkers, and their applicability in diagnostic bone pathology.

TAKE HOME MESSAGE

Molecular analysis has identified key diagnostic biomarkers in only a small proportion of bone tumors. Many of these findings owe their existence to earlier karyotype-based cytogenetic studies. In cases where characteristic cytogenetic findings are absent, there remains a tremendous need to interrogate rigorously these lesions using emerging techniques such as whole genome sequencing. It is assumed that with a more precise understanding of the tumor genetic code, more accurate diagnostic, prognostic and therapeutic markers will emerge.

Gene translocations in musculoskeletal neoplasms

Establishing the best diagnosis for musculoskeletal neoplasms requires a multidisciplinary approach using clinical, radiographic, and histologic analyses. Despite this rigorous approach, establishing accurate diagnoses and prognoses remains challenging. Improved diagnostic methods are expected as unique molecular signals for specific bone and soft tissue cancers are identified. We performed a systematic review of the best available evidence to explore three major applications of molecular genetics that will best benefit clinical management of musculoskeletal neoplasms: diagnostic, prognostic, and therapeutic applications. The specific questions addressed in this systematic review are: (1) What sets of histopathologic sarcoma subtypes will benefit from molecular evaluation and diagnosis? (2) What molecular methods are best applied to histopathologic sarcomas to distinguish between major subtypes? (3) How do the molecular patterns discovered on genetic diagnosis affect prognosis of certain sarcomas? (4) Which sarcoma translocations can benefit from an improved response and outcome using existing and forthcoming pharmacogenetic approaches targeting molecular events? This review summarizes recent advances in molecular genetics that are available and will soon be available to clinicians to better predict outcomes and subsequently help make future treatment decisions.

LEVEL OF EVIDENCE

Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Cytogenetic distinction among benign fibro-osseous lesions of bone in children and adolescents: value of karyotypic findings in differential diagnosis

Benign fibro-osseous lesions of bone (BFOL) comprise a group of clinically distinct entities with significant histologic overlap and often occur in children and adolescents. Because of prior studies indicating that these lesions possess distinct karyotypic abnormalities, we conducted a retrospective review of cytogenetic analyses performed in a series of 16 BFOL in children and adolescents diagnosed at two institutions. These comprised five cases with the diagnosis of ossifying fibroma, four with osteofibrous dysplasia, and seven with fibrous dysplasia arising in the skeleton of 16 children and adolescents. All cases were analyzed using standard G-banding techniques on fresh tumors explanted in tissue culture media. Spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) were used to analyze selected metaphases of a talar lesion with the histologic features of ossifying fibroma. All four confirmed ossifying fibromas, including the talar lesion, contained clonal aberrations fusing breakpoints on Xq26 and 2q33, and one case with dissimilar histology did not. Three of four osteofibrous dysplasias contained multiple copies of chromosomes 8, 12, and/or 21. All but two fibrous dysplasia cases exhibited either a completely normal karyotype or single cell aberrations. One fibrous dysplasia had subtle chromosomal abnormalities not seen in other cases in the series, and another had complex abnormalities involving multiple chromosomes. Our current and published results indicate that cytogenetics might be of ancillary use in the diagnosis of BFOL and that a characteristic chromosomal arrangement is associated with ossifying fibroma.

Recurrent chromosome aberrations in fibrous dysplasia of the bone: a report of the CHAMP study group. CHromosomes And MorPhology

The nosologic status of fibrous dysplasia (FD), a well-known and relatively common bone lesion, is controversial. Information collected by the CHromosomes And MorPhology (CHAMP) study group on published and unpublished cases of fibrous dysplasia shows the presence of clonal chromosome changes in at least a proportion of these lesions. The chromosome aberrations found in FD lesions have been quite variable and have included both structural and numerical changes. Two of the three cases investigated at the study group had trisomy 2 as the sole acquired anomaly. Combined with previously published data, +2 and rearrangements involving chromosome band 12p13 have each been detected in 3 of 8 cases with abnormal karyotype of 11 in which chromosomal analysis has been performed, suggesting that FD is a neoplastic lesion rather than a "dysplastic" process, as has been generally believed and as implied by its very name.

Trisomies 8 and 20 characterize a subgroup of benign fibrous lesions arising in both soft tissue and bone

Trisomy 8 and trisomy 20 are nonrandom aberrations in desmoid tumors. The presence of these trisomies in related benign fibrous lesions of bone has not been previously addressed. In this study, 22 specimens from 19 patients diagnosed with desmoid tumor, desmoplastic fibroma, periosteal desmoid tumor, osteofibrous dysplasia, or fibrous dysplasia were examined by cytogenetic analysis of short-term cultures and bi-color fluorescence in situ hybridization of cytological touch preparations or paraffin-embedded tissue with centromeric probes for chromosomes 8 and 20. Trisomy 8 and trisomy 20 were detected by molecular cytogenetic methodologies in 15 specimens, including 10 primary bone lesions. Traditional cytogenetic analysis revealed trisomy 8 in two cases of osteofibrous dysplasia. Our findings demonstrate that trisomy 8 and trisomy 20 are also nonrandom aberrations in histologically similar, but clinically distinct, benign fibrous lesions of bone.

Aberrations of chromosomes 1 and 17 in six human osteosarcoma cell lines using double-target fluorescence in situ hybridization

Analysis of six human osteosarcoma cell lines was performed by using double-target fluorescence in situ hybridization (FISH). FISH was applied to interphase nuclei, not to metaphase chromosomes. In this study, numerical aberrations of chromosomes 1 and 17 or structural chromosomal aberrations of chromosome arm 1p or 17p, in which it has been suggested that there are one or more tumor suppressor genes in various malignant tumors, were examined with this technique. All six of the human osteosarcoma cell lines studied had extra copies of chromosomes 1 and 17. A high frequency of deletions (> 60%) in chromosome 1 was found in two cell lines and deletions of chromosome 17 were found in one cell line.

Multiple polysomies in nasal polyps in children

Karyotyping of a nasal polyp from a 10-year-old girl revealed multiple numerical chromosome changes. Extra copies of chromosome 5, 7, 8, 12, 16, 17, 18, 19, 20, and 21 were present. Only one cytogenetically abnormal nasal polyp of a child has been reported in the literature. The karyotypes of the reported and the present case are remarkably similar. The significance of this finding in a nonneoplastic proliferation is discussed.

Nonrandom chromosome breakpoints at Xq26 and 2q33 characterize cemento-ossifying fibromas of the orbit

BACKGROUND

Cytogenetic reports of histologically benign fibroosseous lesions are rare, with only nine previously reported cases. None of these previous studies revealed consistent numerical or structural chromosome aberrations, and to the authors' knowledge, no karyotypic abnormalities in cemento-ossifying fibromas of the orbit have been reported.

METHODS

Short term in situ culture and Giesma-band chromosome methods were used to analyze three cementifying fibromas of the orbit: one from a 13-year-old African American male, one from a 14-year-old Hispanic male, and one from a 17-year-old white male.

RESULTS

Cytogenetic findings in these three cases revealed the presence of identical chromosomal breakpoints occurring in all three tumors at bands Xq26 and 2q33. Two of the tumors showed an identical t(X;2)(q26;q33) reciprocal translocation as the sole abnormality. The third tumor revealed an interstitial insertion of bands 2q24.2q33 into Xq26 as the sole abnormality.

CONCLUSIONS

The authors described new nonrandom breakpoints in fibroosseous lesions of the orbit, which can result from at least two different types of structural chromosomal aberrations. The identification of recurring breakpoints at Xq26 and 2q33 provides a new cytogenetic tumor marker for the identification of this tumor subtype. The sublocalization of breakpoints in this tumor should provide important information for the precise localization and characterization of genes involved in the histiogenesis of these lesions.