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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