3 replies to this topic

[Happycat]

I realized in going over my reports that I never received the FISH report from my initial diagnosis.  So I asked for it at the last Dr's appt.  Since they initially suspected I had APML, they were looking for that in the FISH at first.  The FISH results are somewhat confusing to me.

The FISH was done on PB.  The report clearly states in what I surmise is a summary that 199/200 cells showed BCR-ABL, and that 9-22 translocation was detected by karyotype and FISH.

It then  says the 15-17 translocation (for APML) was not detected by FISH.

I won't type in the CML part, since that is understandable.  The weird part is related to the FISH for 15-17 translocation.  Here is what it says:

Fluorescent in situ hybridisation (FISH) was undertaken on a smear of this sample, using a cocktail of probes for the t(15;17) (PML/RARA cytocell).  Two hundred interphase nuclei were examined and 100/200 cells (50%) had an aberrant pattern of signals, with one RARA signal appearing to be half-size in about 50% of the cells and lost in the remaining cells.  This result is outside the reference range for the probe (diploidy and no fusion signals in 98.81-100% cells) and suggested a translocation involving RARA with another chromosome.  Following the identification of t(9;22) above, the experiment was repeated.  While the same phenomenon was observed in a small number of the non-dividing nuclei, in the dividing (metaphase) cells, 20/20 metaphases examined had two equally sized RARA signals.  This suggests that the previous result was due to technical artifact, and that there is no RARA deletion at this level of resolution.

Then it has the standard disclaimer "please remember that this analysis does not eliminate the possibility of alterations at the molecular level, chromosomal mosaicism involving abnormal cells lines of low frequency or small structural abnormalities".

Of course, I am most worried that the strange RARA results ARE due to some small abnormalities not picked up on the later tests, and that some day soon, my CML will transform into a rare APML blast crisis.  (It does happen, but it's extremely rare.)

At the time I saw the doctor, I had not yet seen this FISH report, but I did press him on chromosome 17 abnormalities I was told about while in the hospital.  (There also is a line in my karyotype report that says one cell (of 20) showed an additional loss of chromosomes, which he told me verbally at the hospital was chromosome 17.   The report calls it technical artifact, and I know from my own research that loss of chromosomes is not considered clonal until at least 3 cells show it. But I've got no clue what causes a technical artifact for karyotyping.)

The doctor said the chromosome 17 abnormality on FISH indicated it was simply a bad test.  They got bad results that weren't trustworthy.  He said it was a bad probe or a bad test.  

So, I am left wondering what "technical artifact" would cause a FISH signal for RARA (or any other chromosome) to be diminished?  Bad probes?  How is a probe "bad"?  Is a blood smear more prone to error than other types of cell preps?  (The FISH for t(9;22) does not mention a smear, only the t(15:17) says smear.  I don't know how FISH samples are normally prepped for analysis.  Are they all on smears?)

The first RARA test was run on interphase cells, on the same day as drawn.  The second test was run the next day on the same sample, after they discovered the t(9;22).  Would this affect the quality of the test, e.g., can I trust the 2nd test?  It mentions that the same phenomenon was present in a small number of the non-dividing (interphase) cells, even though the metaphase cells appeared normal for RARA signals.  What does this imply?  That the probe didn't bind well to interphase cells?  Are metaphase results always preferable to interphase results?

Any insight would be appreciated!  Sorry if this is confusing, but I myself am confused.

Traci

[Trey]

It is certainly a confusing report.  The report says it used the Cytocell FISH, which is described here:

http://www.cytocell....information.asp

Your doc is probably right about the test failure, but rather then trying to figure out the implications of those FISH -- which is probably not possible due to the conflicting results -- it would be best to repeat the tests.  Your CML treatment would not improve the RARA issue, if it exists, so it would still be detectable.  If it were me, I would prefer a repeat BMB and use of marrow fluid for the FISH.

You had previously said that the docs suspected APL in the first place because of the high number of promyelocytes. I suggested some other possible reasons for the high levels:

http://community.lls...e/100035#100035

What did the later testing show regarding your promyelocyte levels?  I would think that if they remain high, then you have an issue.  If not, then it was more likely a test failure along with other reasons for the high promyelocytes.  The CML treatment would not affect APL if it was also present, so those symptoms would remain and could still be detected by testing, which is why I would repeat that testing.

[Happycat]

Trey,

Thanks for the reply.  Glad to think someone else finds it confusing.  Just written oddly to me.  The whole report is written out of sequence in time, so it's hard to follow.

The report does say that the 2nd test "suggests" the first one was in error, which is at least more accurate than saying it "proved" it was in error.  The only thing it really proves is that the two results are in conflict.  I guess the scientist in me would like to see a third test to break the tie.  I'd also like to know if they track the lot number of the probe used, and whether or not they get different results with different lots of the same probe.

Anyway, they were checking blood smears early on for each visit, and they were not finding any promyelocytes.  But that's all on PB samples.  I haven't had a follow up BMB, as my onc generally thinks the PB information is just as good most of the time.  So, if it is just as good, then no promyelocytes is a good thing for me.

Like you said, the TKI wouldn't touch any RARA problems, so if that were an issue, you'd think it would have shown up by now.

Thanks again,

Tarci

[Trey]

If it were me, I would want to settle the issue with another BMB.