In AWK, how to insert the value of variable as string at the beginning of the line

Problem solved: it is due to the hidden "ctrl-Ms". I used the following awk code to remove them:

awk '{ gsub("\r", ""); print $0;}'

I try to insert a variable as a string at the beginning lines with a match.

The updated example, between &&&&&& lines, which is a bit long but needed for explaining my codes. I try to extract some information from each case (with unique case # as SP 15 xxxx). I want to insert case numbers at the front of each lines of diagnosis (using the variable of "old_case")

&&&&&&

MEDICAL RECORD |                   SURGICAL PATHOLOGY       Pg  1 of 2 

PATHOLOGY REPORT      Accession No. SP 15 1111 

Submitted by:                               Date obtained: 

Specimen (Received ):
RIGHT, RIGHT RIGHT RIGHT

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

PATHOLOGY REPORT         Accession No. SP 15 1111

Gross description:
The specimen is received in one formalin filled container, labeled

Microscopic Diagnosis:
     Lung, right right right right, left left 
         DX:  CHANGES CHANGES CHANGES
              NO EVIDENCE OF MALIGNANCY 
              (PLEASE SEE DESCRIPTION)

/es/ signature, M.D.

&&&&&&

My whole script is as follows:

#! /bin/awk -f

BEGIN {  old_case = "0000"; }

/Accession No./  {if (old_case != $7) {old_case = $7; print "Acc#",$5,$6,$7 > "output"} else {}};            
/Microscopic Diagnosis:/ {flag=1;next} /\/es\// || /SUPPLEMENTARY/ {flag=0} flag {print old_case,$0 > "output"};

END { }

The result I got is:

Acc# SP 15 1111
1111
      Lung, right right right right, left left 
1111
          DX:  CHANGES CHANGES CHANGES
1111
               NO EVIDENCE OF MALIGNANCY
1111
               (PLEASE SEE DESCRIPTION)
1111
1111

It appears that a new line breaker was added each time the variable "old_case" printed. On the other hand, if I use just a string "test" instead of variables (with the following code)

/Microscopic Diagnosis:/ {flag=1;next} /\/es\// {flag=0} flag {print "test",$0 > "output"};

the result is as follows, which is what I want to get:

Acc# SP 15 1111 
test      Lung, right right right right, left left 
test          DX:  CHANGES CHANGES CHANGES
test               NO EVIDENCE OF MALIGNANCY 
test               (PLEASE SEE DESCRIPTION) 
test 
test

I am using Mac OSX 10.9.5