Convert/Cast NULL value to 'NULL' AS String in SSRS Report

Hi,

I have a report query where I need to display in SSRS report the string "NULL" if there is no value in the column.

Does anyone know how to show the string "NULL" instead of just a blank cell in an SSRS Report?  My code snippet:

MAX(CASE WHEN parm = 'sed' AND percentile = '50' THEN CONVERT(varchar(18), convert(numeric(10,3), 100.0 * Pct_Reduction)) ELSE NULL END)

However, the above simply shows a blank cell for a null value.  I need to show the actual word, "NULL", when there is a null value.

Is this possible?

Marilyn Gambone