Linda,
This question is right up my alley as I have seen one of these in practice
and have dicussed this rare benign fibrohistiocytic adipose tissue tumor
that can be mistaken for a malignancy with Drs Cyril Fisher (two years ago
at IAP in Boston) and Saul Suster (last month in Amsterdam at the IAP
congress where he presented one) the doctors who originally described the
tumor. What are you trying to stain? Is this for a seminar or proficeincy
testing? If it is the constituent dendritic cells themselves, then  CD34
stains the bulk of the dendritic cells, which are basically primitive
dendritic fibroblasts. No antigen retrieval is necessary on formalin-fixed
tissue for CD34.  There is a second population of dendritic cells in
dendritic cell fibromyxolipoma, dendritic histiocytes that express
coagulation factor XIIIa. In my experience these constitute from 20% up to
focally 40% of the cells. Formalin fixed tissue needs a 20-30 minute trypsin
digestion followed by a 30 minute incubation in rabbit- anti human factor
XIIIa (calbiochem) diluted 1:400 in PBS with 1 % BSA. If it is the myxoid
matrix that you are trying to stain, alcian blue should do nicely. Some
examples of dendritic fibromyxolipoma may be more fibrogenic and less myxoid
and maybe less staininable ground substance. My modified Movat Pentachrome
will show you the varying degrees of fibrogenesis (yellow stained by
saffron) and ground substance (alcian blue) Areas with both appear green.
 Hope this helps. If you want, you can send me the block and I'll play with
it.

Jeff Silverman HT HTL QIHC (ASCP),  Pathologists' Assistant
Southside Hospital
Bay Shore NY USA




Date: 6 Nov 2002 17:01:03 -0600
From: LindaA@ascp.org
Subject:


Hello Histonetters,
Help.........I'm having difficulty staining soft tissue, diagnosed as
"Dendritic Fibromyxlipoma".  It appears as if the myxoid matrix that is
distinctive for this lesion has been digested and is not present in the
slide.
Does anyone have a staining procedure for this  type of diagnosis?  Thank
you.
_______________
Linda Agnew HT
Operating Services
Technical Support Services
American Society for Clinical Pathology
2100 West Harrison Street
Chicago IL  60612-3798
T  312-738-1336x1108
E  lindaa@ascp.org