Case of the Week 713

 Here is combination case from my archives showing a particular parasite in 3 different preparations of vaginal secretions.

Conventional Pap smear:

ThinPrep Pap smear:

Giemsa-stained cytoprep:

Identification?

Answer to Case 713

 Answer to the Parasite Case of the Week 713: Trichomonas vaginalis trophozoite

As noted by Florida Fan, the Giemsa-stained preparation is ideal for highlighting the key morphologic features of T. vaginalis trophozoites, including the flagella, undulating membrane, and axostyle. In my mind, the Pap stain just doesn't highlight the features as well. Here is an annotated image showing some of these features:

The trophozoites of T. vaginalis are 7-30 micrometers long, are tear drop/pear-shaped (i.e., pyriform), and have 5 flagella. Four flagella are anteriorly directed, while the 5th flagellum runs posteriorly along the undulating membrane. The nucleus is ovoid and there may be visible granules in the cytoplasm. 

Trophozoites infect the squamous epithelial cells of the lower female genitourinary tract, as well as the male urethra and prostate. Historically, it was thought that only a trophozoite form existed, and thus transmission could only be sustained through direct intimate contact (and possibly through shared fomites). However, cyst-like structures (CLS) which can survive exposure to detergents, certain chemicals (e.g., chlorine) and dessication were described in 2020, thus raising the potential for non-sexual transmission. Further studies are needed to better understand this potential transmission route.

Case of the Week 712

This week's beautiful case was donated by Drs. Beal, Saulino and Herrera Rivera from the University of Florida. The following structure was noted on a liver biopsy from a patient with former international residence. What is the diagnosis? Can you describe the key diagnostic features?

Answer to Case 712

 Answer to the Parasite Case of the Week 712: Schistosoma sp. egg within an eosinophilic granuloma.

As nicely described by Idzi (with minor edits from me), "When the eggs are deposited by the female worm in the arterial plexus of intestines/bladder, many of these eggs will flow back to the liver. In the picture, I can’t see the egg’s spine, so the exact species remains unknown, but we can see the refractive egg shell with miracidium inside. At the miracidium’s terebratorium (upper left), we can see one of the two lateral secretory glands (staining basophilic). Right behind this gland, we see part of a ring of nerve cells (surrounding the cephalic gland), creating some of the typical “bulls-eye” aspect. The dark staining round structures everywhere would be germ cells."

It's hard to appreciate the full ring of germ cells ("bulls-eye") in this image, but here is a photo of a different case that nicely shows the ring.