Potential diagnostic implications of breakpoints in the long arm of chromosome 8 in lipoblastoma

Contemporary management of lipoblastoma

PURPOSE

Lipoblastoma is a rare, benign, adipose tissue tumor. We report the largest single institution experience managing these uncommon neoplasms.

METHODS

We retrospectively reviewed 32 cases of lipoblastoma entered in the pathology database at our institution between January 1991 and August 2005. We conducted a comprehensive literature review of lipoblastoma and summarized the results of the largest series published.

RESULTS

Most patients presented with an enlarging, palpable, firm, nontender, mobile mass. The male-to-female ratio was 1.9:1. The anatomical distribution was trunk (n = 12), extremity (n = 12), groin (n = 5), and neck (n = 3). Average age at resection was 2.8 years (range, 2.6 months to 12 years). Thirty-one cases were completely excised, although 1 patient underwent staged partial excision to preserve nerve function. Chromosomal analysis performed in selected patients revealed characteristic aberrations in chromosome 8. Complications included keloid formation (n = 3), wound infection/dehiscence (n = 2), wound seroma (n = 1), and transient brachial plexus neurapraxia (n = 1). Average follow-up was 7.4 months (range, 1 day to 6.5 years); 2 patients were lost to follow-up. There were no recurrences.

CONCLUSIONS

A staged approach with meticulous sparing of the neurovascular bundle provides excellent functional outcome for patients with large tumors. Nonmutilating surgical excision is the treatment of choice.

Omental lipoblastoma

A large intra-abdominal mass was discovered in a 6-month-old boy during a routine well-child examination. Imaging studies revealed a solid mass which appeared to arise from the left lobe of the liver, extending caudally and filling the entire pelvis. At the time of surgical excision, the mass was found to be unassociated with the liver, but was instead localized to the omentum. Histologic examination revealed adipocytes of varying stages of maturation arranged in a lobular architecture, consistent with a lipoblastoma. This unusual tumor is only the eighth reported omental lipoblastoma [J. Hicks, A. Dilley, D. Patel, J. Barrish, S. Zhu, M. Brandt, Lipoblastoma and lipoblastomatosis in infancy and childhood: histologic, ultrastructural, and cytogenetic features. Ultrastruct. Pathol. 25 (2001) 321-333; J. Harrer, G. Hammon, T. Wagner, M. Bolkenius, Lipoblastoma and lipoblastomatosis: a report of two cases and review of the literature. Eur. J. Pediatr. Surg. 11 (2001) 342-349; S. Weiss and J. Goldblum, Enzinger and Weiss's Soft Tissue Tumors, fourth ed., Mosby, St. Louis, MO, 2001, pp. 601-605, 670-686; S. Soin, S. Andronikou, R. Lisle, K. Platt, K. Lakhoo, Omental lipoblastoma in a child; diagnosis based in CT density measurements. J. Pediatr. Hematol. Oncol. 28(1) (2006) 57-58; A. Prando, S. Wallace, J.L. Marins, R.M. Pereira, E.R. de Oliveira, M. Alvarenga, Sonographic features of benign intraperitoneal lipomatous tumors in children-report of 4 cases. Pediatr. Radiol. 20(8) (1990) 571-574; C. Blank, E. Schoenmakers, P. Rogalla, E. Huys, A. Van Rijk, N. Drieschner, J. Bullerdiek, Intragenic breakpoint within RAD51L1 in a t(6;14)(p21.3;q24) of a pulmonary chondroid hamartoma. Cytogenet. Cell Genet. 95 (2001) 17-19; S. Ingraham, R. Lynch, S. Kathiresan, A. Buckler, A. Menon, hREC2, a RAD51-like gene, is disrupted by t(12;14)(q15;q24.1) in a uterine leiomyoma. Cancer Genet. Cytogenet. 115 (1999) 56-61]. Cytogenetics revealed a karyotype of 46,XY,t(8;14)(q13;q24). While lipoblastomas characteristically involve 8q, only one prior case has been reported with 14q24 as its fusion partner [M. He, K. Das, M. Blacksin, J. Benevenia, M. Hameed, A translocation involving the placental growth factor gene is identified in an epithelioid hemangioendothelioma. Cancer Genet. Cytogenet. 168 (2006) 150-154]. We report this unique case of an omental lipoblastoma with a focus on its unusual karyotype, as well as its differentiation from myxoid liposarcoma.

Lipoblastoma and lipoblastomatosis

We report two cases of lipoblastoma of the buttock in a 10-month-old boy and a 20-month-old girl, the first with rearrangement of chromosome 8 and the second without cytogenetic abnormality, and one case of lipoblastomatosis of a leg in a 6-month-old boy with a normal karyotype but with a rearrangement of the PLAG1 gene. Lipoblastoma and lipoblastomatosis are two different presentation of the same rare benign soft tissue mesenchymal tumour arising from fetal white fat and occurring almost exclusively in young children under 3 years. These neoplasms have no malignant potential but may recur in cases of incomplete resection. Histological diagnosis sometimes used to be difficult because of the close resemblance of the lesion with myxoïd liposarcoma. Nowadays, cytogenetic analysis may contribute to the diagnosis by showing abnormalities of the long arm of chromosome 8, leading to rearrangement of the PLAG1 gene. Actual advances in cytogenetic molecular analysis may aid in accurate diagnosis.

Rearrangement of chromosomal region 8q11-13 in lipomatous tumours: correlation with lipoblastoma morphology

Cytogenetics is of considerable value when diagnosing lipomatous tumours, as different tumour types have different more or less specific chromosomal abnormalities. One such entity is lipoblastoma, which is a benign lipomatous tumour that often exhibits rearrangements of chromosome bands 8q11-13, and the gene PLAG1 has been implicated as the target of these chromosomal changes. All lipomatous tumours karyotyped at the Norwegian Radium Hospital were reviewed, looking for rearrangements of 8q11-13. Five tumours exhibiting chromosomal abnormalities affecting this region were found. Only one of them was morphologically diagnosed as a lipoblastoma, two being classified as lipomas, one as a hibernoma, and one as a well-differentiated liposarcoma. The two tumours successfully analysed with bacterial artificial chromosomes (BACs) covering the gene PLAG1 showed involvement of this gene in the rearrangement. The findings raise the question as to what extent the diagnosis lipoblastoma should be based on histopathological or cytogenetic/molecular data or a combination thereof. When karyotypic information from this series was combined with available literature data, it was found that the sensitivity of 8q11-13 rearrangements for diagnosing lipoblastomas when found in a lipomatous tumour was 77% and that the corresponding specificity was 98%. The validity of these calculations of the diagnostic information provided by the cytogenetic findings is, of course, totally dependent on the morphological diagnosis made in each case. Regardless of what the precise phenotypic diagnosis was, it is suggested that lipomatous tumours with 8q11-13 rearrangement constitute a distinct pathogenetic entity. When selective therapies tailor-made against the specific pathogenetic rearrangement become available, it will become mandatory to pay more attention to the genetic constitution of the tumour cells than to their phenotypic appearance.

Lipoblastoma in a four-year-old African child

A four-year old Sudanese child presented with a growing mass in the medial aspect of the right thigh. The mass appeared during the neonatal period. On clinical examination a diagnosis of lipoblastoma was entertained on the basis of the patient's age and the clinical features of the mass. The tumor was completely excised surgically. The clinical diagnosis of lipoblastoma was confirmed pathologically. Follow-up of the patient for 6 months postoperatively showed no evidence of recurrence.

Cervical lipoblastomatosis producing quadriparesis: case report of surgery with chemotherapy and 10-year follow-up

INTRODUCTION

Cervical lipoblastomatosis is a rare spinal tumour. Management of recurrence and long-term outcome data are not well described.

CASE REPORT

A 10-month-old infant presented with an upper extremity weakness. Magnetic resonance imaging (MRI) revealed an extradural cervical spinal tumour. It was debulked and histopathology revealed it to be lipoblastomatosis. The infant improved postoperatively. However, 5 months later the patient deteriorated and developed quadriparesis. The patient was managed with a more extensive resection and had chemotherapy. Ten years post-presentation the patient is well having made a full recovery and is living a normal life. Recent MRI shows minimal residual quiescent tumour.

CONCLUSION

The treatment of cervical lipoblastomatosis should involve the resection of as much tumour as possible at the first sitting as recurrence can be a problem. In cases of spinal recurrence we recommend aggressive decompression and adjuvant chemotherapy.

Lipoblastoma-like tumour of the vulva: report of three cases of a distinctive mesenchymal neoplasm of adipocytic differentiation

AIMS

We sought to delineate and describe three cases of a distinctive mesenchymal neoplasm of the vulva showing adipocytic differentiation and affecting young patients.

METHODS AND RESULTS

In three patients between 13 and 38 years of age, the vulvar tumours had well-circumscribed borders and ranged in size from 35 to 100 mm. Histologically, they were well circumscribed and lobulated. The lobules were separated by thin fibroconnective tissue septa and were composed of slender spindle cells showing slightly eosinophilic cytoplasm with indistinct boundaries, uniform nuclei with finely granular chromatin, and no nucleoli. The cells were embedded in a richly myxoid stroma. The background in all three tumours was a 'chicken-wire', capillary vascular network resembling that seen in myxoid liposarcomas. Two tumours had scattered signet-ring-type lipoblasts and the third a large number of such lipoblasts. Clusters of mature adipocytes were entrapped in the tumours. None had mitotic figures, necrosis, or pleomorphism. The neoplastic cells stained positively for vimentin and were negative for other immunohistochemical markers. Treatment for all three tumours was enucleation alone. After follow-up of 10 years, 7 years, and 1 year, all patients are well with no evidence of disease.

CONCLUSIONS

The benign behaviour of these neoplasms militates against the diagnosis of liposarcoma. We believe these are benign lesions of adipocytic differentiation akin to infantile lipoblastomas.

Evidence by spectral karyotyping that 8q11.2 is nonrandomly involved in lipoblastoma

We report two cases of lipoblastoma with chromosome 8-related aberrations, ie, a 92,XXYY,t(7;8Xp22;q11.2)x2 [8]/46,XY[16] in Case 1 and a 46,XY,-8,-13,add(16) (q22),+mar, +r [cp13]/46,XY[7] in Case 2. Using spectral karyotyping and fluorescence in situ hybridization techniques, the karyotype of Case 2 was redesignated as 46,XY, r(8), del(13)(q12), der(16)ins(16;8)(q22; q24q11.2)[cp13]/46,XY[7]. This report delineates a new chromosome rearrangement, ie, der(16)ins(16;8)(q22; q24q11.2) in lipoblastoma, and also confirms the t(7; 8)(p22;q11.2), reported only once previously, as a recurrent translocation involved in such a tumor. These findings provide valuable information for clinical molecular cytogenetic diagnosis of lipoblastoma. Furthermore, this report highlights the value of cytogenetic and molecular cytogenetic analysis in differential diagnosis of childhood adipose tissue tumors and adds to the number of lipoblastomas reported with chromosomal abnormalities at 8q11.2.

Case of lipoblastoma with two derivative chromosomes 8 containing homogeneously staining-like regions and a review of the literature: lipoblastoma and chromosome 8

We report a case of a lipoblastoma in a 10-month-old girl in which the cytogenetic aberration showed a homogeneously staining-like region (hsr) within two derivative chromosomes 8. There was a loss of one normal copy of chromosome 8 and gain of two identical derivative chromosomes 8 with the karyotype designation 47,XX,psu idic(8)(pter-->q12 approximately 13::hsr::q12 approximately 13-->pter),+psu idic (8)(pter-->q12 approximately 13::hsr::q12 approximately 13-->pter). This is the first report of a chromosomal aberration of this type seen in lipoblastoma.

The cytogenetic and molecular characterization of benign and malignant soft tissue tumors

Cytogenetic analyses of benign and malignant soft tissue tumors have led to the description of recurrent, specific, and even pathognomonic chromosomal translocations and/or other rearrangements in most types of soft tissue tumors. The consistent karyotypic rearrangements have provided critical diagnostic information in this group of neoplasms that often presents significant diagnostic challenges to the clinician and the pathologist. These findings have also been instrumental in the characterization of the abnormalities at the molecular level. Novel genes have been isolated from the translocation junctions and the mechanisms of their deregulation identified. This has increased our understanding of the histogenesis of these tumors, paved the way for the molecular diagnosis of many sarcomas, aided in directing therapy, and also provided important prognostic information.

Forehead lipoblastoma mimicking a hemangioma

A case of forehead lipoblastoma simulating a hemangioma in a male infant is reported, to alert pediatricians to this rare tumor and to increase the index of suspicion in atypical hemangiomas. A 2-month-old male infant developed a protruding forehead mass with increased vascularity. It demonstrated progressive and accelerated growth over the subsequent 6 months, unresponsive to steroid therapy. A magnetic resonance imaging scan supported the diagnosis of hemangioma because of the hypervascular nature of the lesion. Surgical excision was performed because of visual obstruction. Pathologic examination of the specimen was consistent with a very primitive lipoblastoma. This tumor is a rare, benign lesion of immature fat cells that is found almost exclusively in the pediatric population. Lipoblastomas are more common in males than females and frequently present as asymptomatic, rapidly enlarging, soft lobular masses on the extremities. Complete surgical excision is the definitive treatment. In the vast majority of reported cases, however, the preoperative diagnosis was incorrect, underscoring the diagnostic dilemma presented by these rare tumors.

Lipoblastoma: a case with t(7;8)(q31;q13)

Lipoblastoma is a rare benign adipose tumor which, in all of the cases so far described, presents an involvement of chromosome 8 in the region 8q11-13. We hereby report the results of the second case of lipoblastoma studied by fluorescence in situ hybridization (FISH), in a 13-month-old boy. An abnormal karyotype 46,XY,t(7;8)(q31;q13) was found in 90% of the metaphases examined, in agreement with the previously reported observations. We suggest the region 8q11-13 may contain a relevant locus for lipoblastoma origin.

Tumor karyotype differentiates lipoblastoma from liposarcoma

Lipoblastoma is a rare benign pediatric soft tissue tumor that may be difficult to distinguish from a myxoid liposarcoma clinically or histologically. The authors present a case of a progressively growing, locally invasive soft tissue tumor in a child. Tissue culture for cytogenetic study showed a breakpoint in the long arm of chromosome 8. A review of the literature showed seven case reports of lipoblastoma karyotype, six of which had a similar breakpoint in chromosome 8. This distinguishes it from the histologically alike myxoid liposarcoma, the karyotype of which typically contains the clonal anomaly t(12;16)(q13:p11). The authors recommend that when performing a biopsy of a childhood adipose tumor with unusual features, such as progressive or invasive growth, that fresh tissue be submitted for cell culture. The tumor karyotype will, in most cases, aid in differentiating lipoblastoma from myxoid liposarcoma.

A 2-Mb YAC contig and physical map covering the chromosome 8q12 breakpoint cluster region in pleomorphic adenomas of the salivary glands

Pleomorphic adenomas are benign epithelial tumors originating from the major and minor salivary glands. Extensive cytogenetic studies have demonstrated that they frequently show chromosome abnormalities involving chromosome 8, with consistent breakpoints at 8q12. In previous studies, we have shown that these breakpoints are located in a 9-cM interval between MOS/D8S285 and D8S260. Here, we describe directional chromosome walking studies starting from D8S260 as well as D8S285. Using the CEPH and ICRF YAC libraries, these studies resulted in the construction of two nonoverlapping YAC contigs of about 2 and 5 Mb, respectively. Initial fluorescence in situ hybridization (FISH) analysis suggested that the majority of 8q12 breakpoints clustered within the 2-Mb contig, which was mapped to the centromeric part of chromosome band 8q12. This contig has at least double coverage and consists of 34 overlapping YAC clones. The localization of the YACs was confirmed by FISH analysis. On the basis of mapping data of landmarks with an average spacing of 65 kb as well as restriction enzyme analysis, a long-range physical map was established for the chromosome region spanned by the 2-Mb contig. The relative positions of various known genes and expressed sequence tags within this contig were also determined. Subsequent FISH analyses of pleomorphic adenomas using YACs as well as cosmids revealed that all but two of the 8q12 breakpoints in the primary tumors tested mapped within a 300-kb interval between the MOS proto-oncogene and STS EM156. The target gene affected by the chromosome aberrations mapping within this interval was recently shown to be the PLAG1 gene, which encodes a novel zinc finger protein.

Chromosomal aberration in lipoblastoma: a case with 46,XX,ins(8;6)(q11.2;q13q27)

Chromosomal aberrations involving 8q11.2 have been reported in lipoblastoma. We report here a case of lipoblastoma with new chromosomal aberration. 46,XX,ins(8;6)(q11.2;q13q27). Cytogenetic analysis would facilitate the clinical differentiation between myxoid liposarcoma and the pathologically similar lipoblastoma and the identification of genetic loci related to cellular growth.

Identification of a yeast artificial chromosome spanning the 8q12 translocation breakpoint in pleomorphic adenomas with t(3;8)(p21;q12)

A subgroup of pleomorphic adenomas of the salivary glands is characterized by translocations involving chromosome 8, with consistent breakpoints at 8q12. As part of a positional cloning effort to isolate the gene(s) affected by these translocations we now report the mapping of the 8q12 breakpoint in two primary pleomorphic adenomas with the recurrent t(3;8)(p21;q12). Yeast artificial chromosome (YAC) clones corresponding to eight different loci in 8q11-12 were isolated and mapped by fluorescence in situ hybridization (FISH). The t(3;8) breakpoint was mapped within a 1 Mb region flanked by MOS proximally and by the genetic marker D8S166 distally. One YAC within this region was shown to span the t(3;8) breakpoint in two tumors. This YAC will provide an excellent tool for isolating the gene(s) at the breakpoint(s) in adenomas with t(3;8).

A novel reciprocal translocation (14;15)(q11;q24) in a congenital mesoblastic nephroma

We describe a novel reciprocal translocation, t(14;15)(q11;q24), as the sole cytogenetic aberration in a congenital mesoblastic nephroma. The tumor was predominantly of "classic" morphology, but with small cellular islands of larger cells indicating early transformation to the cellular type. This is the first report of a reciprocal translocation as the sole anomaly in a congenital mesoblastic nephroma.

Physical map of a YAC contig containing the region of the human gene (HYRC) complementing hyper-radiosensitivity of the scid mouse mutation

We previously mapped the putative human HYRC (the hyper-radiosensitivity of the scid mutation, complementing gene) to human chromosome 8q11.1 by fluorescence in situ hybridization (FISH) using Alu-based PCR products from a mouse-human scid radiation cell hybrid (RD15/5) as probes. From a cosmid library constructed from RD15/5, 57 cosmid clones containing human DNA inserts were isolated. 18 of which were mapped to 8q11. Based on the sequences of plasmid subclones of the 18 cosmids, five novel sequence-tagged-sites (STSs) were made. By a screening of the CEPH-YAC library with these STSs, five yeast artificial chromosome (YAC) clones were isolated. All these YAC clones were confirmed not to be chimeric by FISH, but two of them showed deleted human insert DNAs. Using the other 3 non-deleted YACs, we constructed a physical map covering the HYRC region. We confirmed that the recently isolated gene (the DNA-PKcs gene) which is a strong candidate for HYRC is located within the present contig and spans less than 200 kb. This map will be useful for the analysis of the genomic structure of the DNA-PKcs gene and for isolation of other complementing genes in the HYRC region.

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.

Low-grade astrocytoma with a complex four-breakpoint inversion of chromosome 8 as the sole cytogenetic aberration

We report a case of a low-grade astrocytoma in a 10-year-old boy in which the sole cytogenetic aberration was a complex four-breakpoint inversion of chromosome 8 with the karyotype designation 46,XY,der(8)inv(8)(p23q24)inv(8)(q11q21). Two protooncogenes on chromosome 8, MOS at 8q11 and MYC at 8q24, are located at or near the bands which correspond to two of the breakpoints in this inversion. The localization of the structural aberrations to four breakpoints on chromosome 8 provides a rare example of a solid tumor with structural aberrations limited to a single chromosome.