Derm Flashcards
T or F: Dogs and cats can make Vitamin D in their skin
FALSE- No they cannot! Little 7-dehydrocholesterol is found in
the skin of cats and dogs (and likely other carnivores), and
therefore little vitamin D is produced in the skin – that is
because they have high enzymatic activity of 7DH reductase
which converts 7-dehydrocholesterol into cholesterol, reducing
concentrations of this vitamin D precursor in the skin and
preventing its conversion to cholecalciferol
T or F: The diagnosis of Demodex sp. requires histopathology
FALSE- no you
can obtain a diagnosis via SKIN SCRAPING easily! (this diagnosis
should not require histopathology)
T or F: Secondary lesions (crusts) are not diagnostic
FALSE- they ARE! Don’t
scrub or clip them off!
T or F: It is best to biopsy before the use of therapy or after an
appropriate withdrawal period
TRUE
Your colleague asks your opinion on a 10 year old white
cat that has had ulcerated/crusty ear tips for some time
and now has enlarged submandibular lymph nodes.
What tumor would be at the top of
your list?
Squamous cell carcinoma
T or F: Most tumors in the perineal region are benign, castration and surgical
removal will be curative
FALSE- there’s malignant and benign ones – the
benign ones are derived from the perianal hepatoid glands (modified
sebaceous glands); the ones from the anal sac are apocrine in nature and
most are malignant!
T or F: apocrine gland anal sac adenocarcinoma are mostly locally infiltrative and nothing to worry about
FALSE- no, this is definitely a ”need to WORRY” cancer, again yes locally infiltrative but claim to fame is
WIDESPREAD METASTASIS quick
What is a common senile change in dogs?
sebaceous nodular hyperplasia
You notice a tumor that appears to arise from the anal sac on physical
examination of a 7 year old intact male dog. What should next steps be?
biopsy with staging (abdominal and thoracic
radiographs)
Three year old horse with verrucous to nodular, firm,
lesions that has appeared to grow over the past few
months on the face. What is most likely tumor type?
Sarcoid - Most common neoplasm in the
HORSE! Often on the face
6 year old dog presents to you with
bilaterally symmetric, non-pruritic
alopecia, in addition to firm,
thickened, sometimes gritty
ulcerated and alopecic plaques. The
dog also has a pendulous abdomen
and reported to be polyphagic by the
owner.What disease should be at the top of
your list?
Hyperadrenocorticism
5 year old, high-energy dog with year-round
allergies that is crated for long periods of time
during the day. Single lesion that started out as
a plaque and over time progressed to a nodule,
and then most recently became ulcerated.
* A. This is probably a case of acral lick dermatitis
* B. This is Vitamin A responsive dermatosis
* C. This is pemphigus foliaceus
* D. This is probably a drug-reaction
A. Acral Lick Dermatitis
A group of young piglets have been fighting and then shortly after develop exudative dermatologic lesions; some of the piglets have died.
What is your highest clinical suspicion?
Staphylococcus hyicus
7-year old dog with a history of vesicles that quickly progress to striking
ulcers in the oral cavity and a few areas of skin (with crusting). You suspect:* A. Pemphigus foliaceus
* B. Epitheliotropic lymphoma
* C. Pemphigus vulgaris & Bullous Pemphigoid
* D. Discoid lupus erythematosus
Pemphigus vulgaris (PV) & Bullous Pemphigoid (BP) – Correct! BP results in dermalepidermal
clefting, ulceration, which includes oral cavity and MCJs lesions!! Oral mucosa
almost always a presenting complaint with PV.
5-year-old mostly outdoor male castrated cat
presents with the following lesions in the
inguinal fat pad region. These lesions are
nodular and have multiple draining tracts. Your
highest clinical suspicion is that this is what?
Atypical mycobacteriosis - groin overlying inguinal fat pad is the MOST COMMON SITE (site is a tip-off!); wound
contamination or traumatic implantation, nodular and draining tracts
5-year old mixed breed mare presents to you with a history of
being turned out on pastures with standing water in a
tropical/subtropical climate. What is your top differential?
Pythium insidiosum – oomycete, standing water,
ulcerative and proliferative (limbs & trunk) – KEY here is the standing water, tropical/subtropical climate
6-month old puppy with lesions starting out on the face and legs and then progressed. You
perform a skin scraping and find cigar-shaped mites. What is your diagnosis?
Demodicosis - would see scaly, alopecic areas throughout the body, together with a skin scrape showing the classic cigar shaped Demodex mites
Pig with red roughly rhomboid shaped areas on skin. What is most likely cause?
Erysipelothrix rhusiopathiae- can cause a septicemic disease resulting in cutaneous infarcts that are
rhomboidal in shape, diamond skin disease.
A cat presents with circular lesions under the upper lip. What is the top differential?
Hypersensitivity response- indolent ulcer is one of the manifestations of food, flea
allergy, and atopy in cats
What are 3 important functions of skin?
Pigmentation, Vit D synthesis with sunlight (not in dogs and cats!) and barrier to fluid/electrolyte loss
What cells are responsible for pigmentation?
Melanocytes, melanin granules
What is the keratinized layer of the skin called?
Stratum corneum
What separates dermis and epidermis and is important in immune mediated skin disease?
Basement membrane
What connects keratinocytes together and what happens when these are targeted in immune-mediated skin diseases?
Desmosomes, keratinocytes separate and epidermis falls apart- get breach in barrier function
For skin biopsies, what are the main do’s (3) and don’t (1)?
DO: collect multiple sites, Include CRUSTS, Biopsy before therapy- non treated lesions!
DON’T: surgically prepare site before taking samples
What are the 5(.5) types of round cell tumors?
Lymphoma, Transmissible Venereal Tumor, Mast Cell Tumors, Plasma Cell Tumors, Histiocytic Tumors, +/- Melanoma because it can look like anything
What is a common non-neoplastic and/or hyperplastic epithelial tumor?
Skin tags aka acrochordons. Dogs > Cats.
What is a common benign neoplastic epithelial tumor? Characteristic presentation? Prognosis?
Viral papilloma. Exophytic mass on muzzle/face of young animal that may spontaneously regress.
What is a common malignant neoplasm of epidermal cells?
Squamous cell carcinoma.
What are characteristic predilection sites/risk factors for Squamous cell carcinoma? Prognosis?
Solar damage, lack of hair/pigment. Proliferative to ulcerative non-healing lesions. Classic is older white cat with crusty ear margins or dog with subungual tumor. Locally aggressive.
What is a common apocrine gland tumor in dogs? Prognosis? Sequelae?
AGASACA. Most common malignant neoplasm in perianal region of dogs. Highly metastatic. Paraneoplastic hypercalcemia of malignancy due to secretion of PTHrp.
What is a common mesenchymal skin tumor which is non-neoplastic? Defining characteristics?
Harmartoma. Either “scrambled” skin or “dermis on crack”
What is the most common skin tumor of horses? What type of cells?
Equine sarcoids. Tumor of mesenchymal origin.
What is predisposing factor and typical signalment for equine sarcoids? Cause?
Areas of wounds/trauma. Typical signalment: Young horse. Associated with Bovine papillomavirus
What is prognosis for Equine sarcoids?
Locally invasive and recurrent. Goes deep. Hard to excise. Spindly cells.
What is the most common MESENCHYMAL tumor of cats? What are the 2 common clinical manifestations? Prognosis?
Fibrosarcoma. Spontaneous or injection-associated. Locally aggressive.
Which is more aggressive, spontaneous or injection-associated sarcomas?
Injection/vaccine-associated sarcomas are more locally aggressive than spontaneous. More difficult to excise and recur commonly.
What is the dog counterpart to feline fibrosarcoma? Prognosis?
“Soft tissue sarcomas”. Locally invasive.
What are the characteristics of a lipoma?
Benign, expansile, greasy freely moveable, older dogs. Cytology shows adipose cells. Bulges on cut surface.
What are the two types of cutaneous vascular tumors? Cells or origin?
Hemangioma, Hemangiosarcoma. Endothelial cells.
Predilection factors for hemangioma?
Dogs, sunlight exposure.
How do you differentiate hemangioma from hemangiosarcoma?
Histology, staging.
How is cutaneous hemangiosarcoma related to multicentric disease in dogs?
Cutaneous tumors are usually solitary and not part of the multicentric syndrome that involved spleen, lungs, liver and right auricle. They are usually less aggressive, but should still biopsy and stage.
What does cutaneous lymphoma/Lymphosarcoma look like? What species do we see it in? Prognosis?
HIGHLY VARIABLE. Nodules, plaques, might just look like dermatitis. Could just be change in pigment in an area. Cats/Dogs. Slowly progressive. Malignant form is Epitheliotropic lymphosarcoma (“mycosis fungoides”).