Difference between revisions of "Basics"

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*Melanoma = classically pigmented, often a prominent [[red nucleolus]], a mix of spindle cells and epithelioid cells, mix of cohesive and dyscohesive cells.
*Melanoma = classically pigmented, often a prominent [[red nucleolus]], a mix of spindle cells and epithelioid cells, mix of cohesive and dyscohesive cells.


===Histomorphologic classification===
===A practical histomorphologic differential diagnosis of malignancy===
Types of cells:
<center>
*[[Spindle cell]]:
{{familytree/start}}
**Tapered at both ends.<ref>URL: [http://www.medterms.com/script/main/art.asp?articlekey=25657 http://www.medterms.com/script/main/art.asp?articlekey=25657]. Accessed on: 18 January 2010.</ref>
{{familytree | | | | | | | | | | | A | | | | | | | | | | |A=Malignancy}}
**Suggests mesenchyme, i.e. sarcoma, compatible with melanoma and some carcinomas.
{{familytree | |,|-|-|-|v|-|-|-|v|-|^|-|v|-|-|-|v|-|-|-|.| |}}
*Plasmacytoid cell.
{{familytree | B | | C | | D | | E | | F | |G |B=Large epithelioid tumours|C=Spindle cell tumours|D=Small blue cell tumours|E=Pleomorphic tumours|F=Clear cell tumours|G=Myxoid tumours}}
**Resemble a plasma cell: eccentric nucleus, moderate basophilic cytoplasm, +/-"clockface" chromatin pattern (clumping of chromatin at the periphery of the nucleus), +/-perinuclear hof (crescentic cytoplasmic clearing adjacent to the nucleus; represents abundant Golgi apparatus).  
{{familytree/end}}
*Epithelioid cell.
</center>
**Looks like epithelium - cell borders touch neighbouring cells so that the cells collectively form a barrier.
*[[Small round blue cell tumour]]/lymphoid:
**Small cells with scant cytoplasm.
***"Small" is classically 2x a "resting lymphocyte" diameter.
****Diameter of a "resting lymphocyte" ~ diameter of a [[red blood cell]] (RBC) ~ 8 micrometres.
****Most carcinoma cells are 3-4x the size of a RBC.
*Small lymphoid ([[small cell lymphoma]]).
**"Small" in the context of lymphoid is classically ~1x a "resting lymphocyte" diameter.
**Often not malignant by cytology.


==Differential diagnosis by site==
==Differential diagnosis by site==
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