Liposarcoma pathophysiology: Difference between revisions
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According to the WHO classification described previously, well differentiated liposarcomas may be sub-classified into 3 types: ''sclerosing''; ''adipocytic''; and ''inflammatory''. | According to the WHO classification described previously, well differentiated liposarcomas may be sub-classified into 3 types: ''sclerosing''; ''adipocytic''; and ''inflammatory''. | ||
====Sclerosing Liposarcoma==== | ====Sclerosing Liposarcoma==== | ||
Occurs most frequently at the retroperitoneum and paratesticular regions. | |||
====Adipocytic Liposarcoma==== | ====Adipocytic Liposarcoma==== | ||
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Microscopically, the main histologic finding is the presence of scattered, distinctive, bizarre stromal cells associated with rare multivacuolated lipoblasts set in a fibrillary collagenous background (Fig 3). Occasionally the fibrous component represents the vast majority of the neoplasm to the extent that lipogenic areas can be easily overlooked or even missed in a small tissue sample (Fig 4). | |||
Adipocytic liposar- coma is mostly composed of mature adipocytes exhibit- ing striking variation in cell size and at least focal nuclear atypia and hyperchromasia (Fig 1). Scattered hyperchromatic stromal cells may be encountered within fibrous septa. Of course, a varying number (from many to none) of monovacuolated or multivacuolated lipo- blasts (defined by the presence of single or multiple sharply marginated cytoplasmic vacuoles that indent an enlarged hyperchromatic nucleus) may be found (Fig 2). It is a commonly held opinion that lipoblasts represent the hallmark for any type of malignant adipocytic lesion. | Adipocytic liposar- coma is mostly composed of mature adipocytes exhibit- ing striking variation in cell size and at least focal nuclear atypia and hyperchromasia (Fig 1). Scattered hyperchromatic stromal cells may be encountered within fibrous septa. Of course, a varying number (from many to none) of monovacuolated or multivacuolated lipo- blasts (defined by the presence of single or multiple sharply marginated cytoplasmic vacuoles that indent an enlarged hyperchromatic nucleus) may be found (Fig 2). It is a commonly held opinion that lipoblasts represent the hallmark for any type of malignant adipocytic lesion. | ||
However, it is important to emphasize that the mere presence of lipoblasts does not make (or is required for) a diagnosis of liposarcoma. As a matter of fact, there exist a number of entirely benign adipocytic lesions (eg, lipoblastoma, pleomorphic lipoma, chondroid lipoma) that may contain numerous lipoblasts. By contrast, the absence of lipoblasts within an adipocytic neoplasm fulfilling all the remaining diagnostic criteria for liposar- coma does not prevent such a diagnosis. | However, it is important to emphasize that the mere presence of lipoblasts does not make (or is required for) a diagnosis of liposarcoma. As a matter of fact, there exist a number of entirely benign adipocytic lesions (eg, lipoblastoma, pleomorphic lipoma, chondroid lipoma) that may contain numerous lipoblasts. By contrast, the absence of lipoblasts within an adipocytic neoplasm fulfilling all the remaining diagnostic criteria for liposar- coma does not prevent such a diagnosis. | ||
Another morphologic variation that represents a potential diagnostic pitfall is the presence of a chronic inflammatory infiltrate to the extent that the adipocytic nature of the neoplasm can be obscured (Fig 5). The existence of examples of liposarcoma characterized by the presence of prominent mononuclear inflammatory infiltrates has been acknowledged since the publication of Stout’s5 classification of liposarcoma. Nonetheless, reports dealing specifically with this subtype have not been available until very recently.6,7 The inflammatory infiltrate is usually composed of polyphenotypic lympho- plasmacytic aggregates in which a B-cell phenotype tends to predominate. However, cases exist in which a T-cell population represents the main inflammatory component. Differential diagnosis includes nonadipo- cytic lesions such as inflammatory myofibroblastic tu- mor and Castleman’s disease. Careful as well as exten- sive sampling is mandatory to permit recognition of the adipocytic component that otherwise could be easily missed. The presence of bizarre multinucleate stromal cells represents a useful diagnostic clue. | Another morphologic variation that represents a potential diagnostic pitfall is the presence of a chronic inflammatory infiltrate to the extent that the adipocytic nature of the neoplasm can be obscured (Fig 5). The existence of examples of liposarcoma characterized by the presence of prominent mononuclear inflammatory infiltrates has been acknowledged since the publication of Stout’s5 classification of liposarcoma. Nonetheless, reports dealing specifically with this subtype have not been available until very recently.6,7 The inflammatory infiltrate is usually composed of polyphenotypic lympho- plasmacytic aggregates in which a B-cell phenotype tends to predominate. However, cases exist in which a T-cell population represents the main inflammatory component. Differential diagnosis includes nonadipo- cytic lesions such as inflammatory myofibroblastic tu- mor and Castleman’s disease. Careful as well as exten- sive sampling is mandatory to permit recognition of the adipocytic component that otherwise could be easily missed. The presence of bizarre multinucleate stromal cells represents a useful diagnostic clue. | ||
Revision as of 15:14, 19 September 2014
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Liposarcoma Microchapters |
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Diagnosis |
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Treatment |
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Case Studies |
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Liposarcoma pathophysiology On the Web |
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American Roentgen Ray Society Images of Liposarcoma pathophysiology |
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Risk calculators and risk factors for Liposarcoma pathophysiology |
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.
Adipocytic Liposarcoma
Inflammatory Liposarcoma
Dedifferentiated Liposarcoma
Myxoid Liposarcoma
Round Cell Liposarcoma
Pleomorphic Liposarcoma
Genetics
Associated Conditions
Gross Pathology
Microscopic Pathology
References
- ↑ 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.