How To Modify Some Data Without Changing Everything

Please HELP!

I need to UPDATE a column by removing only the first occurance of $$sp;. I use the following to get an idea of what I have:

SELECT Reporting_Title_Html FROM Lab_Test Where RTRIM(Reporting_Title_Html)='$$sp;'
Reporting_Title_Html
------------------------------
$$sp;
$$sp;
$$sp;
$$sp;
$$sp;Thyroid maintenance required;$$sp..........

Get 5 Records....One record has multiple occurances of $$sp throughout the Reporting_Title_Html column.

I thought I could do:
Update Lab_Test Set Reporting_Title_Html=' ' Where RTRIM(Reporting_Title_Html)='$$sp;'

But I can't lose the trailing data from record #5. This is just a small sampling of what I'm trying to fix.

Any Ideas???

I've thought about REPLACE but that would replace all the $$sp's and I only want to change the very first one from $$sp to ' ' --> blank