Sunday, March 23, 2014

Case of the Week 297

A patient was noted to have rapidly increasing serum creatinine 4 months after receiving a renal allograft. A renal biopsy was performed, which revealed small oval/elongate objects within the renale tubules.  (CLICK ON IMAGES TO ENLARGE).  A variety of stains and additional studies were performed:
H&E, 200x
 H&E, 400x
 H&E, 1000x (note how tiny the structures inside the renal tubule cells are)
 The structures were partially acid fast (Ziehl Neelsen, 1000x)
 A Ryan's trichrome performed on tissue nicely highlighted the objects (1000x)
 A urine specimen stained with Ryan's trichrome also showed these structures.
By electron microscopy, the objects were seen within vacuoles in the renal tubular cells.
 Higher magnification by EM:


Dr. Louis Weiss, Albert Einstein College of Medicine said...

Microsporidiosis. Most likely Encephalitozoon cuniculi (although other Encephalitozoon sp. will look like this on EM as well).

Tomáš Macháček said...

Considering the TEM photo, it's definitely microsporidiosis.

BTW: „In the present case, the patient developed persistent fever (38.5°C) 5 months after transplantation and renal dysfunction with serum creatinine of 1.2 mg/dL increasing to 4.7 mg/dL...“ -

mona said...


Anonymous said...

Thanks for the answers, this will be our educational case as we do not perform the acid fast stain for microsporidia in our lab.

Florida Fan

Anonymous said...

I agree with Microsporidium. However the use of Ryan's blue modified Trichrome stain is not specific for the detection of microsporidia spores since other organisms such as yeast can be stained with the same color. In addition, the location of the infection is very rare.


Anonymous said...

Gram stain has worked pretty well in tissue for the larger microsporidia like this one in the small bowel in the poorly treated HIV crowd; does not seem to stain the smaller varieties with the fewer number of spiral structures.

Anonymous said...

I concur, Microsporidia. The TEM did it for me too...Lee

Anonymous said...

so can you diagnose Microspordiosis with an acid fast stain ?
Can someone post how the chemicals are made and how the procedure is done please.

Thanks in advance,


Bobbi Pritt said...

Hans, microsporidia may be focally positive with an acid fast stain. I've only seen 2 cases in tissue where we tried this and both were positive using the Ziehl-Neelsen stain (standard histology preparation). I'm not sure if an acid fast stain used in microbiology (e.g. Kinyoun) would work on other specimens such as stool and urine. Has anyone else tried this? Note that only some of the spores stains (a minority of those present). The Ryan's Trichrome Blue stain did much better in highlighting the spores. We usually don't do this on tissue sections, but tried it in this case after deparaffinizing in xylene and it turned out pretty well!