Nate’s Corner: We Love a Silver Stain, but Your Non-Argyrophilic Casts Do Not

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This past weekend, Arkana Laboratories hosted another live pathology session covering part II of all things intratubular casts (now focused on crystalline intratubular casts). Dr. Zeljko Dvanajscak helmed the microscope, taking viewers through the 4 major categories of crystalline casts- calcium containing,  dysproteinemia related, metabolic/genetic, and drug induced. As we began our journey through viewing calcium containing casts (calcium phosphate and calcium oxalate), we flipped to a Jones methenamine silver stain of calcium phosphate casts in the medulla. As the slide came into view, Dr. Dvanajscak described these casts as being “non-argyrophilic”. Behind computer screens everywhere jaws dropped, and even Dr. Samira Farouk asked for clarification. 

The word ‘argyrophilic’, Dr. Dvanajscak explained, comes from the Greek words ‘argyros’ meaning ‘silver’ and ‘philia’ meaning ‘love’ giving us a ‘silver loving’ material. This means that something that’s not argyrophilic like the calcium phosphate cast that we were viewing, is something that’s not silver loving. Indeed, we saw that the medullary casts shown on the slide did not take up the silver stain, in contrast to the basement membranes (seen in the picture below), which stood out prominently with the silver staining. 

This image shows the silver stain of a medullary calcium phosphate cast. The red arrows point to calcium phosphate, and the green arrows identify the basement membranes of tubules.

Nothing like kidney pathology to help us learn to differentiate our crystalline casts (calcium phosphate crystalline casts will not polarize or pick up silver stain!) and give us a little linguistics lesson at the same time. 

All Arkana LIVE Pathology Sessions can be found here.

Post by Elinor Mannon

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