Not to be confused with “carcinoma of unknown primary,” in this episode of metastatic disease of “origin TBD”, we discuss the workup of a mass noted incidentally on imaging. This is a very high yield topic often faced on solid oncology consults!
Major Points Covered:
Mass found incidentally on imaging → we need to stage always
Initial Workup:
Reasonable to get CBC, CMP, UA, PSA (if male)
Low blood counts, maybe marrow involvement
Cr elevated concern for obstruction possibly
LFTs elevated concern for mass in the biliary/pancreas region
UA w/ hematuria → maybe bladder
But bottom line you’re gonna get a scan, which scan to get though?
Recommend referencing NCCN guidelines to determine additional staging scans
Create an account on nccn.org and look at guidelines by tumor type
Not all cancers require a PET/CT scan
There are newer modalities for imaging other than FDG PET including PSMA PET (prostate), Auxumin PET (prostate), and DOTATE PET (neuroendocrine)
Certain cancers can be diagnosed on imaging alone (RCC and HCC)
Some cancers require Brain MRI for staging
What to biopsy?
FNA often adequate for solid tumors but may need core if non diagnostic
Need core or ideally excisional if highly concerned for lymphoma
Always try to biopsy the site that will upstage
Distant lymph nodes or other metastatic sites
What about tumor markers?
We use this for treatment monitoring, not for diagnostic purposes
Important to establish a baseline to follow, special circumstances for diagnostic purposes to consider below:
PSA in male if concerned about prostate cancer
AFP helpful if concerned for HCC → liver masses in a cirrhotic
AFP and b-HCG if concerned for testicular → young or middle aged male with mediastinal mass
Molecular testing not necessarily needed at the time of biopsy
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