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Difference between revisions of "Rhabdomyosarcoma"
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*Translocation-negative alveolar RMS shares characteristics with | *Translocation-negative alveolar RMS shares gene expression prolifing characteristics with embryonal RMS -- suggesting these can be grouped together. | ||
==Microscopic== | ==Microscopic== | ||
Alveolar rhabdomyosarcoma: | ===Alveolar rhabdomyosarcoma=== | ||
*Alveolus-like pattern | Features:<ref name=PST14feb11>PST. 14 February 2011.</ref> | ||
*Alveolus-like pattern -- '''key low-power feature'''. | |||
**Fibrous septae lined by tumour cells. | **Fibrous septae lined by tumour cells. | ||
***Space between fibrous sepate may be filled with tumour | ***Cells may "fall-off" the septa, i.e. be detached/scattered in the alveolus-like space. | ||
*Eccentric nucleus ( | ***Space between fibrous sepate may be filled with tumour = ''solid variant of alveolar rhabdomyosarcoma''. | ||
* | *Rhabdomyoblasts - '''essentially diagnostic'''. | ||
* | **Eccentric nucleus. | ||
* | **Moderate amount of intensly eosinophilic cytoplasm. | ||
**Striations -- if you're really lucky; these are not common. | |||
Other features: | |||
*Nuclear pleomorphism - common. | |||
*Mitoses - common. | |||
Notes: | |||
*Well-differentiated rhabdomyoblasts are uncommon in alveolar RMS. | |||
===Embryonal rhabdomyosarcoma=== | |||
Features:<ref name=PST14feb11>PST. 14 February 2011.</ref> | |||
*Randomly arranged small cells. | |||
*Myxoid matrix. | |||
*Strap cells: | |||
**Tadpole-like morphology. | |||
*Rhabdomyoblasts - '''essentially diagnostic'''. | |||
**Eccentric nucleus. | |||
**Moderate amount of intensly eosinophilic cytoplasm. | |||
**Striations -- if you're really lucky; these are not common. | |||
====Subtypes of embryonal RMS==== | |||
There are two common subtypes of embryonal RMS. Both of them have a better prognosis that embryonal RMS not otherwise specified (NOS). | |||
Common subtypes: | |||
#Botryoid subtype: | |||
#*Gross: Grape-like morphology. | |||
#*Microscopic: Non-proliferating layer deep to the surface ("Cambrian layer"). | |||
#Spindle cell subtype. | |||
#*General: may mimic [[leiomyosarcoma]] -- which is not common in the pediatric population. | |||
#*Microscopic: vesicular growth pattern, spindle cells. | |||
==IHC== | |||
Panel of muscle markers -- ''DAM'': | |||
*Desmin (best marker). | |||
*Actin. | |||
*Myogenin. | |||
==[[Electronmicroscopy]]== | |||
Features: | |||
*Sarcomeric like structures - usu. in "bent" cells; cells that are U-shaped. | |||
==Molecular diagnostics== | ==Molecular diagnostics== | ||
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Notes: | Notes: | ||
*t(1,13) vs. t(2,13) -- t(1,13) usually: younger age, extremity lesion, localized disease, better survival. | |||
*Several uncommon [[translocations]] exist. | *Several uncommon [[translocations]] exist. | ||
==See also== | ==See also== | ||