[HSF] Curious mitral lesion

[Mark Levinson]

Forum members:

I was asked to see a 50 yo diabetic woman who presented to the  
hospital with an acute CVA (hemiparesis, expressive aphasia).  Workup
was entirely normal except for a round sessile mass in the posterior  
left atrium, about 7 or 8 mm diameter seen in multiple views,  
presumed to be a myxoma.
The mass did not move much, did not prolapse through the mitral  
valve, and appeared solid by echo criteria.    Unlike most myxomas,
it was appeared to be located near annular portion of P2...

I operated thinking this was a myxoma, just in an atypical  
location.   However, when I opened the atrium, it was normal !!    
Empty!   Nada!
I inspected the orifices of each pulmonary vein, and inverted the  
left atrial appendage.    No tumor !    I looked into the LV cavity
(transvalvar) and did not see anything.    There was no stalk-like or  
sessile lesion, and importantly, normal endocardium throughout
with no stain or color change to indicate something might have once  
been there, and then dislodged.

I was puzzled, and somewhat embarrased to close this case and be told  
"its still there" on postop echo, so I ran my finger along
  the left atrial tissue and mitral apparatus....and I felt a soft  
lump under the posterior mitral leaflet.    There was no question on  
palpation
that this was the lesion seen on echo because it was in the exact  
location (behind the attachment point of P2).

The endocardium was slightly whiter, or more pale, in this location,  
and once I had retraction sutures in place, I could now see a bulge
appearing to come from under the endocardium and lifting the  
endocardium, forming a mass that protruded slightly into the cavity.
However, it was soft, not hard.   I wondered if this was a lipoma, as  
can be seen in the septum, but the echo would suggest something
more dense.     And I had to try to explain her stroke.

So, I incised the endocardium to take a look at the mass, and I was  
greeted with a liquified white cheezy material similar to what you see
coming from an old caseous granuloma.    For a brief moment, I  
thought I has just opened a sebaceous cyst!    About 1 or 2 cc of  
this liquified
material was expressed.   It was not purulent in my opinion, but
reminded me of the "milk of calcium" I had heard about in my training  
years back.   I scooped it up and sent for gram stain (negative).   I  
cleaned
the cavity out with swabs and suction.   Visually, the interior of  
the cavity demonstrated muscle fibers and spicules of calcium.    The  
cavity
clearly traveled into the subvalvar myocardium.     There was no  
other evidence of SBE, so I did not see an indication to resect the  
P2, and try
to reconstruct this area.   I was concerned that I would nail the Cx,  
coronary sinus, or induce a posterior AV separation if I ventured too  
far.

So, excised some tissue for biopsy, then packed the cavity with "milk  
of Vancomycin" (home-made) and closed it with interrupted Prolenes,
ligated the LA appendage, and closed. She has done very well, with  
all cultures negative and a normal post-operative course.

However, I can't explain what  I saw.    The pathologists have  
indicated this is probably a granuloma, but it is not a very  
satisfying diagnosis.

What caused her stroke?    Could this liquified material have escaped  
at some point and embolized?

Has anyone seen anything like this before.

I apologize that my still camera photos are not suitable...I do have  
movies but can't seem to get them loaded on my Mac for  
editing....sorrry.

Thanks,

Mark


Mark M. Levinson, MD
Founder, Editor-in-Chief,
The Heart Surgery Forum
WWW: <http://www.hsforum.com>
Email: <mmLevinson at hsforum.com>