View source for Metastasis

<noinclude>{{Top
|author1=[[User:Mikael Häggström|Mikael Häggström]]
|author2=
}}</noinclude>
==Gross processing==
For suspected tumors in bone or other tissue that generally needs decalcification, try to grossly separate some suspicious soft tissue to be processed without decalcification, as decalcification might affect any molecular studies that will later be indicated. See site-specific grossing guidelines for further directions.
<noinclude>
{{Primary tumor versus metastasis}}
</noinclude>
==Metastasis of unknown primary==
{| class="wikitable" align="center"
|+Metastases of unknown primary origin<ref name="pmid25392080">{{cite journal| author=Collado Martín R, García Palomo A, de la Cruz Merino L, Borrega García P, Barón Duarte FJ, Spanish Society for Medical Oncology| title=Clinical guideline SEOM: cancer of unknown primary site. | journal=Clin Transl Oncol | year= 2014 | volume= 16 | issue= 12 | pages= 1091-7 | pmid=25392080 | doi=10.1007/s12094-014-1244-0 | pmc=4239766 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25392080  }} </ref>
|-
| '''Histopathologic type'''<br>- see section below for descriptions<ref name="pmid25392080" /> || '''Relative incidence''' among metastases of unknown primary origin<ref name="pmid25392080" />
|-
| Well and poorly differentiated adenocarcinomas || 50%
|-
| Undifferentiated carcinoma || 30%
|-
| Squamous cell carcinoma || 15%
|-
| Undifferentiated neoplasms || 5%
|}

*{{Memorization-worthy}} '''Do not diagnose a [[renal cell carcinoma]] metastasis without radiologic evidence of a [[renal tumor]].''' To be a plausible primary tumor for a renal cell carcinoma metastasis, a renal tumor should be visible radiologically. In cases of suspected renal cell carcinoma but no renal imaging is available, it is reasonable to ask the ordering doctor to allow you to wait with signing out the pathology report until renal radiology has been performed.

{{Undifferentiated malignancy}}
===Metastatic adenocarcinoma===
[[File:Histopathology of adenocarcinoma.png|thumb|250px|Typical features of adenocarcinomas. In reality, the appearance varies significantly from case to case. Vacuoles are more prominent in mucinous tumors, but can be seen in serous tumors as well.]]
If metastatic adenocarcinoma seems to be the case (always consider this in at least [[lung adenocarcinoma]]), look at the history and radiology reports for a most likely primary. Generally, perform [[immunohistochemistry]] with one or two stains that are most typical for the suspected primary, and optionally add CK7 and CK20 as a broad screening. 

Generally, classify by degree of differentiation as follows:
*Well differentiated: > 95% of tumor has glandular formations
*Moderately differentiated: 50 - 95% glandular
*Poorly differentiated: < 50% glandular
[[File:Well-, moderately and poorly differentiated colorectal adenocarcinoma.png|thumb|370px|center|Degree of differentiation, with example from a [[colorectal adenocarcinoma]].]]
Example report:
{|class=wikitable
| A. Right lung mass, CT-guided needle biopsy:
*Metastatic adenocarcinoma, moderately differentiated.
Comment: Immunohistochemistry was performed, and showed tumor cells positive for CDX2 and CK 20, and negative for CK 7, consistent with metastasis from a gastrointestinal primary tumor.
|}
==Further workup==
Perform additional biomarker testing as per local guidelines for the corresponding primary tumor at metastatic/advanced stage (such as mismatch repair proteins and next generation sequencing in case of metastatic [[colon adenocarcinoma]]).<noinclude>

==Further reading==
*[[Evaluation of suspected malignancies]]
{{Bottom}}
</noinclude>