Liposarcoma pathophysiology: Difference between revisions

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==Genetics==
==Genetics==
===Well-Differentiated Liposarcoma===
===Well-Differentiated Liposarcoma===
Specific diagnostic techniques, such as karyotipic analysis, have showed a specific characteristic of these cells, namely the presence of a large marker chromosome and/or of an extra ring.<ref name="pmid8827023">{{cite journal| author=Rosai J, Akerman M, Dal Cin P, DeWever I, Fletcher CD, Mandahl N et al.| title=Combined morphologic and karyotypic study of 59 atypical lipomatous tumors. Evaluation of their relationship and differential diagnosis with other adipose tissue tumors (a report of the CHAMP Study Group). | journal=Am J Surg Pathol | year= 1996 | volume= 20 | issue= 10 | pages= 1182-9 | pmid=8827023 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8827023  }} </ref>  With the help of in situ hybridization, these rings and/or large markers were noted to accommodate amplified genetic sequences of the 12q13-15 chromosome region.<ref name="pmid8353809">{{cite journal| author=Dal Cin P, Kools P, Sciot R, De Wever I, Van Damme B, Van de Ven W et al.| title=Cytogenetic and fluorescence in situ hybridization investigation of ring chromosomes characterizing a specific pathologic subgroup of adipose tissue tumors. | journal=Cancer Genet Cytogenet | year= 1993 | volume= 68 | issue= 2 | pages= 85-90 | pmid=8353809 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8353809  }} </ref>  
Specific diagnostic techniques, such as karyotipic analysis, have showed a specific characteristic of these cells, namely the presence of a large marker chromosome and/or of an extra ring.<ref name="pmid8827023">{{cite journal| author=Rosai J, Akerman M, Dal Cin P, DeWever I, Fletcher CD, Mandahl N et al.| title=Combined morphologic and karyotypic study of 59 atypical lipomatous tumors. Evaluation of their relationship and differential diagnosis with other adipose tissue tumors (a report of the CHAMP Study Group). | journal=Am J Surg Pathol | year= 1996 | volume= 20 | issue= 10 | pages= 1182-9 | pmid=8827023 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8827023  }} </ref>  With the help of in situ hybridization, these rings and/or large markers were noted to accommodate amplified genetic sequences of the 12q13-15 chromosome region.<ref name="pmid8353809">{{cite journal| author=Dal Cin P, Kools P, Sciot R, De Wever I, Van Damme B, Van de Ven W et al.| title=Cytogenetic and fluorescence in situ hybridization investigation of ring chromosomes characterizing a specific pathologic subgroup of adipose tissue tumors. | journal=Cancer Genet Cytogenet | year= 1993 | volume= 68 | issue= 2 | pages= 85-90 | pmid=8353809 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8353809  }} </ref> This chromosome region is rich in [[protooncogenes]], including the CHOP, CDK4, MDM2, HMGI-C, GLI, SAS, OS1, and the OS9, which play an important role in the [[pathogenesis]] of many [[neoplasms]].  Amplification of some of these regions, with concomitant amplification of their proteins has been demonstrated in this type of [[soft tissue sarcoma]].<ref name="pmid10727978">{{cite journal| author=Dei Tos AP, Doglioni C, Piccinin S, Sciot R, Furlanetto A, Boiocchi M et al.| title=Coordinated expression and amplification of the MDM2, CDK4, and HMGI-C genes in atypical lipomatous tumours. | journal=J Pathol | year= 2000 | volume= 190 | issue= 5 | pages= 531-6 | pmid=10727978 | doi=10.1002/(SICI)1096-9896(200004)190:5<531::AID-PATH579>3.0.CO;2-W | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10727978  }} </ref>
 
 




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The 12q13-15 chromosome re- gion is very complex and contains several important protooncogenes, such as MDM2, CDK4, HMGI-C, SAS, GLI, CHOP, OS1, and OS9, known to play an important role in the molecular pathogenesis of many neoplastic processes. Interestingly, concomitant amplification of HMGI-C (a gene encoding for an architectural transcrip- tion factor involved in adipocytic differentiation), MDM2, and CDK4 (both acting as positive regulators of cell cycle progression at the G1-S checkpoint), as well as overexpression of the proteins thereof has been recently demonstrated in well-differentiated liposarcomas.12 The fact that the 12q13-15 region is also rearranged in ordinary benign lipomas (leading to HMGI-C activa- tion) and the observation of 12q15 duplication in adipo- cytic neoplasms exhibiting minimal atypical changes (C.D.M. Fletcher, unpublished observation) have led to the postulation that ordinary lipomas may form a morphologic and genetic continuum with well-differenti- ated liposarcoma, with the degree of atypia being a gene dosage effect.12
The fact that the 12q13-15 region is also rearranged in ordinary benign lipomas (leading to HMGI-C activa- tion) and the observation of 12q15 duplication in adipo- cytic neoplasms exhibiting minimal atypical changes (C.D.M. Fletcher, unpublished observation) have led to the postulation that ordinary lipomas may form a morphologic and genetic continuum with well-differenti- ated liposarcoma, with the degree of atypia being a gene dosage effect.12


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Revision as of 18:48, 19 September 2014

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

Pathogenesis

According to their class, each liposarcoma will have specific characteristics and pathogenesis:

Well Differentiated Liposarcoma

This type of liposarcoma occurs both at the limbs and retroperitoneum in equal frequency, and occasionally at the mediastinum and spermatic cord, representing about 45% of liposarcomas.[1]

According to the WHO classification described previously, well differentiated liposarcomas may be sub-classified into 3 types: sclerosing; adipocytic; and inflammatory.

Sclerosing Liposarcoma

Occurs most frequently at the retroperitoneum and paratesticular regions. The particular histological finding in this type of well differentiated liposarcoma is the identification of distinctive stromal cells distributed across the tissue, and associated with lipoblasts filled with multiple vacuoles. This association forms a collagenous background of fibrillary appearance. In certain cases the fibrous component of the neoplasm may occupy most of its mass.[1]

Adipocytic Liposarcoma

Frequently composed by adipocytes with different cell sizes, hyperchromasia and nuclear atypia. Fibrous septa may be identified among adipocytes, containing hyperchromatic stromal cells. Besides these two types of cells, mono or multivacuolated lipoblasts may also be identified. These last are characterized by the presence of single (mono) or multiple (multi) peripheral cytoplasmic vacuoles that press on the hyperchromatic nucleus.[1]

In general, adipocytic neoplasms are often identified by the presence of these lipoblasts, however, its presence is not synonym, since multiple benign lesions may contain lipoblasts; nor are they identified in every liposarcoma, as its absence does not prevent the diagnosis of the condition, if remaining criteria are met.[1]

Inflammatory Liposarcoma

Its adipocitic nature may be misidentified due to the heavy chronic inflammatory infiltrate. The inflammatory component is frequently composed of different lympho-plasmacytic aggregates. These tend to be predominantly formed by a specific type of B-cell yet, T-cells may in some cases populate the inflammatory aggregate.[1][2][3] For the diagnosis of inflammatory liposarcoma a large sample is required to avoid missing the adipocitic component of the neoplasm.[1]

Spindle cell lipocarcinoma is a rare adult type of well-differentiated liposarcoma. It results from the proliferation of neural-like spindle cells, organized in a fibrous structure, containing lipoblasts.[4][5]

Dedifferentiated Liposarcoma

Myxoid Liposarcoma

Round Cell Liposarcoma

Pleomorphic Liposarcoma

Genetics

Well-Differentiated Liposarcoma

Specific diagnostic techniques, such as karyotipic analysis, have showed a specific characteristic of these cells, namely the presence of a large marker chromosome and/or of an extra ring.[6] With the help of in situ hybridization, these rings and/or large markers were noted to accommodate amplified genetic sequences of the 12q13-15 chromosome region.[7] This chromosome region is rich in protooncogenes, including the CHOP, CDK4, MDM2, HMGI-C, GLI, SAS, OS1, and the OS9, which play an important role in the pathogenesis of many neoplasms. Amplification of some of these regions, with concomitant amplification of their proteins has been demonstrated in this type of soft tissue sarcoma.[8]



Associated Conditions

Gross Pathology

Microscopic Pathology

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Dei Tos AP (2000). "Liposarcoma: new entities and evolving concepts". Ann Diagn Pathol. 4 (4): 252–66. doi:10.1053/adpa.2000.8133. PMID 10982304.
  2. Kraus MD, Guillou L, Fletcher CD (1997). "Well-differentiated inflammatory liposarcoma: an uncommon and easily overlooked variant of a common sarcoma". Am J Surg Pathol. 21 (5): 518–27. PMID 9158675.
  3. Argani P, Facchetti F, Inghirami G, Rosai J (1997). "Lymphocyte-rich well-differentiated liposarcoma: report of nine cases". Am J Surg Pathol. 21 (8): 884–95. PMID 9255251.
  4. Dei Tos AP, Mentzel T, Newman PL, Fletcher CD (1994). "Spindle cell liposarcoma, a hitherto unrecognized variant of liposarcoma. Analysis of six cases". Am J Surg Pathol. 18 (9): 913–21. PMID 8067512.
  5. Hendrickson WA, Ward KB (1975). "Atomic models for the polypeptide backbones of myohemerythrin and hemerythrin". Biochem Biophys Res Commun. 66 (4): 1349–56. PMID 5.
  6. Rosai J, Akerman M, Dal Cin P, DeWever I, Fletcher CD, Mandahl N; et al. (1996). "Combined morphologic and karyotypic study of 59 atypical lipomatous tumors. Evaluation of their relationship and differential diagnosis with other adipose tissue tumors (a report of the CHAMP Study Group)". Am J Surg Pathol. 20 (10): 1182–9. PMID 8827023.
  7. Dal Cin P, Kools P, Sciot R, De Wever I, Van Damme B, Van de Ven W; et al. (1993). "Cytogenetic and fluorescence in situ hybridization investigation of ring chromosomes characterizing a specific pathologic subgroup of adipose tissue tumors". Cancer Genet Cytogenet. 68 (2): 85–90. PMID 8353809.
  8. Dei Tos AP, Doglioni C, Piccinin S, Sciot R, Furlanetto A, Boiocchi M; et al. (2000). "Coordinated expression and amplification of the MDM2, CDK4, and HMGI-C genes in atypical lipomatous tumours". J Pathol. 190 (5): 531–6. doi:10.1002/(SICI)1096-9896(200004)190:5<531::AID-PATH579>3.0.CO;2-W. PMID 10727978.


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