Reminds me of my first chief tech., who in those far off days of tinctorial special stains only, would always ask following a request, "do you want in negative or positive boss?"
Come to think of it, is immuno so different?

Dr Terry L Marshall, B.A.(Law), M.B.,Ch.B.,F.R.C.Path
 Consultant Pathologist
 Rotherham General Hospital
 South Yorkshire
 England
        terry.marshall@rothgen.nhs.uk

-----Original Message-----
From: Lott, Robert [mailto:Robert.Lott@bhsala.com]
Sent: 20 May 2003 22:56
To: histonet@pathology.swmed.edu
Subject: Colloidal Iron staining in Renal Cell Ca


Fellow Histonetters,
I apologize if I'm repeating what others might have already pointed out... but I hold in my hand a reprint of the paper that started all the fuss about Colloidal Iron staining in Renal Cell Carcinomas.
The paper is entitled:	Colloidal Iron Staining in Renal Epithelial Neoplasms, Including Chromophobe Renal Cell Carcinoma (Emphasis on Technique and Patterns of Staining), American Journal of Surgical Pathology  22(4): 419-424, 1998.

Just as the paper's name implies, the authors concentrate heavily on how much difference "technique" makes in staining renal tumors and subsequently recognizing staining patterns of the different renal cell carcinomas (RCC) (with concentration on recognition of the very malignant "chromophobe RCC" and its very close morphologic resemblance to the benign "renal oncocytoma.")
They stained 62 cases (14 chromophobe RCC, 19 renal oncocytomas, 22 clear cell RCC, 7 papillary RCC) and at least two blocks from each case with 1- traditional Hale's dialysed iron technique (Hale, 1946)  and 2) a modified Mowry's technique (modified form the Muller-Mowry technique(Mowry, 1958).
The difference between the two is that in the modified Mowry method sections are treated in 3% acetic acid for 2 minutes prior to staining in working colloidal iron solution.

Three fine points here which help establish the author's emphasis about the importance of "technique"
1-  Both Hale's and Mowry's methods maintain the pH of the working colloidal iron at 1.9 or lower (very important)
2-  The Muller-Mowry Colloidal Iron stain (Mowry, 1958) is different from this "modified Mowry," in that it uses three  3 min.changes of 12% glacial acetic acid prior to staining with working colloidal iron.  The authors here use only 3% acetic acid for 2 minutes.  The traditional Hale's method uses NO pretreatment in acetic acid.
3-  Working colloidal iron solution in traditional Hale's method is half stock colloidal iron and half 2M acetic acid for 10 min.; working solution in "modified" Mowry technique is stock colloidal iron and 3% acetic acid mixed in a 4:1 ratio; working solution in Muller-Mowry method is stock colloidal iron 10ml / d-water 18ml / conc.acetic acid 12 ml.

The rest of the paper concerns itself with the recognition of the staining patterns of each of the RCCs above.  It is clear that using the "modified" Mowry method that the authors could easily distinguish the staining pattern of all 14 chromophobe RCCs from the 19 morphologically similar renal oncocytomas.  ALL of the chromophobe RCCs demonstrated "diffuse and strong reticular staining patterns in the cytoplasm of tumor cells" and NONE of the renal oncocytomas showed this pattern.

Finally, the article is decorated with beautiful color photographs of all of the above.  There are photos also which demonstrate the difference in Hale's method and this Mowry modification which are quite striking!!  The author's conclude that the modification's they have made to Mowry's method allow diiferentiation between chromophobe RCC and renal oncocytoma.

The next time your pathologist orders a Hale's Colloidal Iron stain on a RCC you might consider the above discussion and what a difference "technique" makes!!!!

Robert L. Lott, HTL(ASCP)
Manager, Anatomic Pathology
Baptist Health System
800 Montclair Road
Birmingham, AL  35213
205-592-5388/205-592-5646 (fax)
robert.lott@bhsala.com



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