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

[The activating GNAS mutation : A survey of fibrous dysplasia, its associated syndromes, and other skeletal and extraskeletal lesions]

Fibrous dysplasia of bone is a connatal but not hereditary disease with monostotic or polyostotic manifestations and may be associated either with the extraskeletal disease McCune-Albright syndrome or with myxoma of the skeletal muscle, termed Mazabraud syndrome.The confirmation of recurrent chromosomal aberrations may lead to the conclusion that fibrous dysplasia is a neoplasia rather than a dysplastic skeletal disease.The primary cause of all forms of the described diseases is the activating GNAS mutation, which is detectable in almost all lesions. Research into the impact of this mutation has increased the understanding of these up to now solely descriptively defined diseases and also allowed easier discrimination of various fibro-osseous skeletal lesions. Current insights suggest that this mutation may also play a pivotal role in other extraskeletal neoplasias.

Mazabraud's Syndrome: A Case Report and Up-To-Date Literature Review

OBJECTIVE

Mazabraud's syndrome is a rare form of bone fibrous dysplasia associated with intramuscular myxomas. Fibrous dysplasia, is generally localized to pelvis and femur and it results in a fragile bone with deformities, pain, pathological fractures and functional impairment. Intramuscular myxomas, are rare benign mesenchymal neoplasms that exceptionally may evolve to malignant forms.

METHODS

This case report describes a 66-year-old woman with Mazabraud's Syndrome (MS), characterized both by monostotic right femur fibrous dysplasia and by a solitary intramuscular myxoma at the right quadriceps muscle, that underwent a long-term treatment (4 years) with intravenous zoledronic acid.

RESULTS

Zoledronic acid therapy rapidly lowered bone pain together with a reduction of intramuscular myxoma volume, but did not affect the extension of fibrous dysplasia. No adverse effects have been observed during treatment.

CONCLUSION

Highly active bisphosphonates are commonly used for the treatment of bone metabolic disorders and they are generally well tolerated. Zoledronic acid may represent a promising alternative to surgical intervention in MS, although its use in rare form of bone fibrous dysplasias is still controversial.

Molecular pathology and its diagnostic use in bone tumors

Bone tumors are considered by most pathologists difficult to diagnose as they are rare, have overlapping morphology, need radiological correlation, and the usefulness of immunohistochemistry is limited, making conventional morphology the cornerstone of the diagnosis. Over the past decade, more and more has become known of the molecular background of bone tumors. Three groups of bone tumors are recognized, namely, tumors with specific translocations combined with a relatively simple karyotype involving chromosomal translocations (Ewing sarcoma, aneurysmal bone cyst), tumors with specific gene mutations or amplifications (chondrosarcoma, fibrous dysplasia, chordoma), and sarcomas with genetic instability and as a consequence complex karyotypes (osteosarcoma). Technical advancements will rapidly reveal new alterations in the more rare sarcoma subtypes for which the molecular background has remained enigmatic. Opening the archives and using new technologies, as well as refinement of existing technologies for decalcified paraffin-embedded tissue, may bring to light more specific genetic aberrations in bone tumors that can be applied in molecular diagnostics in the near future.

Translocation t(12;17)(q24.1;q21) as the sole anomaly in a nasal chondromesenchymal hamartoma arising in a patient with pleuropulmonary blastoma

The identification of recurrent chromosomal abnormalities in benign and malignant mesenchymal neoplasms has provided important pathogenetic insight as well as powerful diagnostic adjuncts. Nasal chondromesenchymal hamartoma (NCMH), an extremely rare benign tumor arising in the sinonasal tract of infants and children, has not been previously subjected to cytogenetic analysis. Histopathologically composed of mixed mesenchymal elements, NCMH exhibits a relatively wide differential diagnosis to include chondromyxoid fibroma, chondroblastoma, aneurysmal bone cyst, fibrous dysplasia, and osteochondromyxoma. An interesting association with pleuropulmonary blastoma has been reported in a small subset of NCMH patients. In the current study, cytogenetic analysis of a NCMH arising in an 11-year-old boy with a past medical history of pleuropulmonary blastoma revealed a novel 12;17 translocation, t(12;17)(q24.1;q21), as the sole anomaly.

Nonossifying fibroma secondary to aneurysmal bone cyst in the mandibular condyle

Nonossifying fibromas (NOFs) are benign lesions that unusually occur in the mandible. Nonossifying fibromas are asymptomatic and spontaneous resolution at skeletal maturity. Nonossifying fibromas associated with aneurysmal bone cyst (ABC) are very rare. In this clinical report, NOF secondary to ABC in the mandibular condyle was reported; however, it presents different clinical behavior than the usual NOF. In this case, severe destruction in the mandibular condyle as a characteristic of NOF was seen. In the follow-up period, no recurrence was seen subsequent to treatment of lesion with complete resection. Treatment of NOFs with secondary ABC would require aggressive intervention than the treatment of usual NOF.

Molecular pathology of sarcomas: concepts and clinical implications

The molecular genetic changes that have been described in sarcomas over the past era have aided our understanding of their pathogenesis. The majority of sarcomas carry nonspecific genetic changes within a background of a complex karyotype. These constitute the challenges in sarcoma research for unraveling a putative multistep genetic model, such as for chondrosarcoma, and finding targets for therapeutic strategies. Approximately 15-20% of mesenchymal tumors carry a specific translocation within a relatively simple karyotype. The resulting fusion products act either as transcription factors upregulating genes responsible for tumor growth, as for instance in Ewing sarcoma, or translocate a highly active promoter in front of an oncogene driving tumor formation, as for instance in aneurysmal bone cyst. In addition, a small subset of mesenchymal tumors have specific somatic mutations driving oncogenesis. The specific genetic changes unraveled so far had great impact on the classification of bone and soft tissue tumors. In addition, these changes can assist the pathologist in the differential diagnosis of some of these entities, especially within the groups of small blue round cell tumors and spindle cell tumors, if performed in specialized centers. While a putative association between certain fusion products and outcome is still under debate, the role of predicting response of targeted therapy has been well established for KIT and PDGFRA mutations in gastrointestinal stromal tumors.

Fibrous dysplasia of the cervical spine presenting as a pathological fracture

Fibrous dysplasia (FD) is an uncommon benign fibro-osseous abnormality of bone, of unknown aetiology and equal sex incidence, which is most commonly restricted to one bone (monostotic FD: MFD, 70%). Less commonly multiple bones are affected (polyostotic FD: PFD, 27%). Vertebral involvement is uncommon (4%), but more common with PFD (7 - 24%) than MFD (1%). Of 20 cases of FD involving the cervical spine, only three have represented MFD. Unlike cases associated with PFD, all cases presented with acute neck pain without significant neurological impairment after minor trauma. We present the case of a 35-year-old male with MFD who developed a pathological fracture of C3 following minor trauma. Radiographs showed collapse and typical 'ground glass' lucency of C3. CT revealed replacement of C3 cancellous bone by hypodense tissue extending into the right lateral mass. The cortex was thinned and fractured, and encroached upon the right foramen transversarium and spinal canal. Magnetic resonance imaging demonstrated hypo-intensity on both T1 and T2, with uniform contrast enhancement. Subtotal excision was achieved via an anterior C3 corpectomy, with residual FD left within the right lateral mass. Stability was achieved utilizing an iliac crest strut autograft, C2-4 plate-and-screws, and mobilization in a halo frame for 3 months. At 18 months, he remained asymptomatic and without deficit. Radiography, CT and MRI confirmed graft fusion without FD invasion, but with residual right lateral mass FD unchanged in size.

Fibrous Dysplasia Masquerading as Extramedullary Relapse After Bone Marrow Transplantation for Chronic Myeloid Leukemia

A 19-year old girl suffered from relapse of chronic myeloid leukemia (CML) after bone marrow transplantation. The disease was controlled by interferon and imatinib mesylate, but was complicated by autoimmune hyperthyroidism. She presented with unilateral proptosis with no extraocular muscle or visual defect at 26 months follow-up. Systemic investigations showed no recurrence of leukemia or thyrotoxicosis. Magnetic resonance imaging revealed an extensive retro-orbital base of skull lesion. A trans-oral biopsy showed fibrous dysplasia and continuous observation was advised. The unusual sequence of events and the differential diagnoses for unilateral proptosis in post bone marrow transplantation (BMT) cases are discussed.

Secondary osteosarcoma arising in fibrous dysplasia, case report

Malignant transformation of fibrous dysplasia is very rare. The frequency is increased in polyostotic forms, in McCune-Albright and Mazabraud's syndromes and previously irradiated cases. Pain, which is rapidly becoming worse over a short period unrelated to trauma is the most alarming symptom. Early radiological features of sarcomatous transformation are moth-eaten or cystic areas of osteolysis, cortical destruction and gradual formation of a soft tissue mass. The prognosis is unfavorable as most of the cases are in an advanced stage in the time of diagnosis. We present an unusual case of unsuspected secondary osteosarcoma arising in a previously unirradiated, monostotic fibrous dysplasia. A 46-year-old woman was admitted with hip pain, which worsened after a minor trauma occurred 1 year ago. Plain graphies of left femur showed a well-delineated lesion with endosteal scalloping and areas having a ground-glass appearance. The MRI revealed minimal contrast enhancement but no heterogenous signal intensity, cortical destruction, periost reaction or accompanying soft tissue component was noted. The lesion was initially curetted. But being diagnosed as osteosarcoma histologically, classical osteosarcoma protocol pre and postoperative chemotherapy was applied. Resected femur showed areas of fibrous dysplasia admixed with osteosarcoma having fibroblastic, chondroblastic and osteoblastic areas that were focally invading the soft tissue. Tumor viability was estimated as 95%. The clinical course worsened rapidly after the operation. She did not respond to postoperative chemotherapy and lost with pulmonary metastases less than a years' time after the operation. The case is presented to increase awareness on the possibility of malignant transformation in an otherwise unsuspected fibrous dysplasia.

F-18 fluorodeoxyglucose (FDG) PET in the diagnosis of malignant transformation of fibrous dysplasia in the pelvic bones

Fibrous dysplasia (FD) is a benign dysplastic pathology of bone-forming mesenchymal cells, resulting in replacement of trabecular bone by abnormal fibrous and immature osseous tissue. FD can be either monostotic or polyostotic, is more often unilateral, and can be part of the McCune-Albright syndrome (MIM 174800). Sarcomatous degeneration in FD is rare, ranging from less than 1% in monostotic forms to 4% in the McCune-Albright syndrome. We report the case of a 59-year-old woman with monostotic FD of the left ischium, known for over 30 years, who developed sarcomatous transformation in a low-grade spindle-cell sarcoma. The value of F-18 fluorodeoxyglucose positron emission tomography in the early diagnosis of malignant transformation, the evaluation of distant metastasis, as well as monitoring the efficacy of chemotherapy are discussed.

Clonal status of fibrous dysplasia

AIM

The purpose of this study was to elucidate the clonality of fibrous dysplasia based on X-chromosome inactivation mosaicism and polymorphism in female somatic cells at the phosphoglycerate kinase (PGK) and androgen receptor (AR) loci using microdissection technology.

MATERIALS AND METHODS

Nine patients with fibrous dysplasia were examined using clonality assays based on X-chromosome inactivation mosaicism. Lesions and surrounding soft tissues were microdissected from paraffin sections, and genomic DNA was extracted, pretreated with Hpa II or Hha I, and the PGK and AR genes were amplified by nested PCR. The single nucleotide polymorphism (SNP) at the PGK locus was identified by incubation with Bst XI and agarose gel electrophoresis. The CAG repeat length polymorphism at the AR locus was revealed on denaturing polyacrylamide gels and visualised by silver staining.

RESULT

Microscopically, typical histological characteristics were seen in each sample. Lesions consisted of varying proportions of fibrous tissue and immature trabecular bone. Tissue consisted of collagenous fibres and fish-hook or comma-shaped trabecular bone without rows of cuboidal appositional osteoblasts on the surface. Restriction fragment length polymorphism (RFLP) of AR was found in seven of nine cases. The results of clonality assays demonstrated that seven cases of fibrous dysplasia were monoclonal, suggesting that they are neoplastic lesions.

CONCLUSION

We conclude that fibrous dysplasia may not be a hyperplastic lesion, but a neoplastic lesion. Additional studies with larger sample sizes will be needed to conclusively prove our hypothesis.

Solitary intramuscular myxoma with monostotic fibrous dysplasia as a rare variant of Mazabraud's syndrome

The rare coexistence of intramuscular myxoma (IM) and fibrous dysplasia (FD) is known as Mazabraud's syndrome. IM tends to occur multifocally and is associated most frequently with polyostotic FD in Mazabraud's syndrome. We present an extremely rare combination of a solitary IM and monostotic FD as a variant of Mazabraud's syndrome, and discuss the importance of recognizing this rare coexistence for appropriate management of the patient.

Concurrent Ewing sarcoma family of tumors and fibrous dysplasia: possible diagnostic pitfall

We present 2 patients with synchronous Ewing sarcoma family of tumors (ESFTs) and fibro-osseous lesion in the independent sites, possibly causing misjudgment in staging. Each patient showed another activity apart from the primary ESFT lesion on gallium and/or thallium scintigraphy at initial presentation. Of note is that such lesions showed no obvious radiologic change even though the primary ESFT lesions were mildly shrunken during chemotherapy. The biopsies confirmed fibrous dysplasia (FD) in the first patient and fibro-osseous lesion, possibly FD in the second patient. As far as we know, concurrent ESFT and FD in independent sites have never been described. However, this unusual combination emphasized the possibility of concurrent FD mimicking metastasis in a patient with malignancy and the view that exploratory biopsy should be performed in a critical case to make staging. Further investigation will be required about whether the co-occurrence of ESFD and FD in our patients is coincidence or genetic linkage.

Ewing's sarcoma of the humerus mimicking fibrous dysplasia on imaging and biological behavior

We present the case of a 12-year-old girl who presented with a pathological fracture through a benign-appearing osteolytic lesion that was presumed to represent fibrous dysplasia. The fracture healed, and over the next 2.5 years there was further refracturing and healing with progressive osteolysis. A biopsy was performed and revealed Ewing's sarcoma. The disease was locally controlled by neoadjuvant chemotherapy and radiation therapy. The patient is disease free with excellent function 6 years following the discovery of the lesion. We illustrate and discuss the sequence of events.

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.

Osteosarcoma in a patient with McCune-Albright syndrome and Mazabraud's syndrome: a case report emphasizing the cytological and cytogenetic findings

Osteosarcomatous transformation in fibrous dysplasia is unusual. The incidence is increased in patients with concomitant Mazabraud's syndrome and McCune-Albright syndrome. We report the cytological, histological, and cytogenetic findings of this rare entity arising from a mass in the right elbow of a 44-year-old African-American woman. The fine-needle aspiration (FNA) findings were diagnostic of malignancy, with markedly atypical spindle and polygonal cells admixed with osteoid. The diagnosis of osteosarcoma by FNA was subsequently further confirmed by histological evaluation of an above-elbow amputation specimen. Fluorescence in situ hybridization and comparative genomic hybridization demonstrated trisomies of chromosomes 5 and 7 in the fibrous dysplasia and osteosarcoma. In addition, multiple chromosomal abnormalities were also noted in the osteosarcoma. We are unaware of any previous reports of the cytogenetic findings in the tissue of this rare condition, and argue for the value of FNA in the evaluation of such patients under selected conditions.

Mosaic trisomy 2 in myelodysplastic syndromes and acute myeloblastic leukemias

We present a short report here of two more patients with trisomy 2 as the sole chromosomal abnormality in a hematologic malignancy. Although trisomy 2 is a recognized abnormality in neoplasms, particularly hepatoblastomas, to the best of our knowledge only three other cases have been reported with trisomy 2, in patients with a hematologic malignancy. The two cases presented here of myelodysplastic syndrome transforming to acute myeloblastic leukemia and chronic myelomonocytic leukemia showed trisomy 2 as the sole abnormality.

Translocation (1;4)(p31;q34) in nonossifying fibroma

Nonossifying fibroma is a benign, lytic lesion of fibrous origin most often observed in the metaphyseal region of the long bones in children and adolescents. It is frequently asymptomatic and is often characterized by a history of spontaneous resolution. Herein, we report a clinicohistopathologically typical case of nonossifying fibroma arising in the tibia of an 18-year-old skeletally mature female. Conventional cytogenetic analysis revealed a reciprocal translocation involving bands 1p31 and 4q34 [t(1;4)(p31;q34)]. To the best of our knowledge, this is only the second reported case of a clonally aberrant nonossifying fibroma.

Coamplification of 12p11 and 12q13 approximately q22 in multiple ring chromosomes in a spindle cell sarcoma resolved by novel multicolor fluorescence in situ hybridization analysis

An 80-year-old male presented with a lobulated mass in the lower abdominal wall. A diagnosis of an intermediate grade myofibroblastic spindle cell sarcoma was made. Cytogenetic analysis demonstrated a complex karyotype with a der(6), a small marker and five, different in size, ring chromosomes. Fluorescence in situ hybridization (FISH), multiplex FISH, and multicolor banding analysis was used to further delineate this complex karyotype. The der(6) was shown to be a der(18)t(6;18;9;12;18), the marker chromosome was identified as del(17), and the ring chromosomes as r(9) and r(12;18)x4. Amplification of 18 and coamplification of 12p and 12q was detected in the ring and marker chromosomes. No intercellular heterogeneity was observed although a few micronuclei containing chromosome 18 and anaphase bridges, containing chromosome 12 material, the result of bridge-fusion-bridge (BFB) cycles, were observed. Our findings combined with results from others indicate that amplification of chromosomes 12 and 18 as well as BFB phenomena characterize this type of sarcoma.