Necrotizing Meningoencephalitis - Canine
The etiology of necrotizing meningoencephalitis is "idiopathic". This basically means that we really have no idea what causes it, but "idiopathic" sounds so much better than "we have no idea" doesn't it?
The brain is normally distinctly divided into grey matter and white matter regions. On the left side of the image, you can see the white matter clearly well-demarcated from the grey matter surrounding it.
On the right side of the image, however, the brain is inflamed and the margin between the grey matter and white matter has become very indistinct. There is an image available if you do not see the area of inflammation.
Click on the image to see a general enlargement of the brain section.
So, you should use the word indistinct when you see a lesion that blends into the surrounding tissue and cannot be readily delineated or defined. Compare indistinct to well-demarcated.
Transitional Cell Carcinoma - Canine Urinary tract
This malignant neoplasm has entered and actively destroyed the surrounding tissue - hence it is termed invasive or infiltrative. Invasiveness is generally a property of malignant neoplasms. Hyperemia is visible. Hydroureter can occur when a tumor obstructs the outflow of urine from the bladder.
Select the image to reveal a magnification of the tumor.
Papillomas are caused by papovaviruses. Papillomas consist of thickened epidermis and have multiple finger-like projections of epidermis. They can be surgically excised or they may regress spontaneously.
Papillary is similar to villous but papillary means more nipple-like while villous means more finger-like. That is, papillary projections are not quite as long as villous projections.
For more information on papillomas and other dermatologic disorders, please see the Dermatopathology section of CAL.
Pedunculated means "having a stalk or peduncle". Do you see the little stalk at the base of the skin tag? It looks somewhat like a miniature tree trunk.
Well, in pathology we do not say a mass "looks like a little shrub" or is "broccoli-like". Remember - no food adjectives! Instead we say it is pedunculated.
Click on the photo to see an enlarged image.
Toxic Epidermal Necrolysis
Serpiginous means "having a wavy border". And if you look closely at this photo of a dog's underside, you can see a wavy margin between the red dermis and the white epidermis. An enlargement depicting the serpiginous margin is available (84 K).
You may be wondering why this dog's belly is so red. Well, as the name of this condition implies, the epidermis has undergone a full thickness necrosis and is basically gone, thus exposing the dermis underneath.
This necrosis is associated with certain drugs. It looks absolutely horrible and the dog is at a high risk for developing secondary infections. Click on the image to view an enlargement of the photo.
A good way to remember the word serpiginous is to think of a slithering serpent. Both are wavy - and that's what serpiginous means - "having a wavy border".
Serrated means "having a saw-like edge". Think of a bread knife. They also have serrated margins.
This serrated liver is actually one of the normal anatomic variations in the dog. It is an incidental finding at necropsy.
Select the photo to reveal a close-up of the serrated margin.
The red lump on this dog's pinna is not a jellybean or even an engorged tick - it's a histiocytoma with a sessile attachment.
Sessile means "having a broad base".
This tumor is attached to the ear by a broad base - so we can say it is sessile. Compare this image to pedunculated, in which the mass is attached by a stem or peduncle. So the point here is that it is important not only to describe the tumor itself (in this case: red, ovoid, smooth) but also to describe its attachment to the tissue (in this case: sessile).
Click on the image to see an enlargement.
Lymphangiectasia - Small Intestine
The many "fingers" projecting out at you from this section of intestine are called villi - hence tissues that have finger-like margins resembling these are known as "villous".
These villi are distended due to lymphangiectasia.
Click on the image to reveal a magnification of the villous projections.
Sertoli cell tumor in a 10 y.o. Collie
Sertoli cell tumors are a common type of testicular tumor. They can be functional and may secrete estrogen. This excess hormone production leads to hyperestrogenism and feminization.
The Sertoli cell tumor at left is clearly well-demarcated from the surrounding testicular parenchyma. There is a clear delineation between the pink tumor and the light brown tissue of the testis. Some tumors infiltrate the surrounding tissue or are more indistinct, but this one is well-demarcated.