Derm Path 4 ()

• What causes the formation of a callus?

  Repetitive pressure or friction, especially over a bony prominence

  
• What causes the formation of decubital ulcers ("bed sores" or "saddle sores")?


  Constant pressure to a localized area

  
• What causes the formation of a hygroma ("false/acquired bursa")?

  Repeat trauma/pressure points can cause the formation of a hygroma, or a cystic cavity filled with fluid

  
• What causes the formation of intertrigo?

  Intertrigo is a form of localized dermatitis that occurs in skin folds due to friction and moisture. Commonly seen in folds of brachycephalic dogs or around the vulva.

  
• What causes the formation of "hot spots"?

  Pyotraumatic dermatitis, or "hot spots" are a common complication of any pruritic dermatosis (itch-scratch cycle).

  
• What causes the formation of "lick granulomas"?

  Acral lick dermatitis, or "lick granuomas" are caused by psychogenic foot chewing/licking, flank suckling, or tail biting. These areas are prone to secondary infection.

  
• List clinical differentials for exuberant granulation tissue in a horse

  - Pythiosis ("Kunkers"/"swamp cancer")

  - Cutaneous habronemiasis

  - Neoplasia (SCC)

  - Sarcoids
• What is calcinosis circumscripta?

  Calcium deposition in the skin over bony prominences

  
• Compare and contrast calcinosis circumscripta to calcinosis cutis

  Calcinosis circumscripta is simply deposition of mineral in the tissues. It is not a degenerative process.

  Calcinosis cutis is mineralization and degeneration of collagen.
• What is the pathogenesis for ergotism in cattle?

  
  

  (Ergotism of the tail is pictured)

  Claviceps purpurea is a fungus that grows on grain. The fungus produces mycotoxins (ergot alkaloids), which are vasoactive compounds that cause ischemic necrosis (dry gangrene) of the extremities.

  *Note: ergotism is from moldy grain, and fescue toxicosis is from moldy grass, but otherwise the pathogenesis is the same

  
• What is the pathogenesis for fescue toxicosis in cattle?

  
  

  ("Fescue foot" is pictured)

  Fescue is commonly infected by a fungus that produces ergot alkaloids, which are vasoactive compounds that cause ischemic necrosis (dry gangrene) of the extremities.

  *Note: ergotism is from moldy grain, and fescue toxicosis is from moldy grass, but otherwise the pathogenesis is the same

  
• What are the three types of photosensitization?

  - Primary (type I)

  - Type II

  - Secondary/hepatogenous (type III)
• What causes primary/type I photosensitization? Give an example.

  Primary/type I:Ingestion of plants or drugs containing photodynamic pigments

  Example:St. John's wort

  
• What causes type II photosensitization?

  Type II: Hereditary defect in heme synthesis called porphyria causes endogenous photodynamic pigment accumulation
• What causes secondary/hepatogenous type III photosensitization? Give an example.

  Secondary/hepatogenous (type III): Hepatocellular injury or biliary obstruction causes decreased capacity of the liver to excrete photodynamic pigments and they accumulate.

  Example: Phylloerythrin accumulates in herbivores

  
• What kind of skin is affected by photosensitization?

  Non-pigmented skin
• What is a cyst?

  Non-neoplastic, sac-like structure with an epithelial lining that must be completely removed to be cured.

  
• What is a harmartoma?

  A benign, tumor-like nodule composed of disorganized & excessive amounts of tissue or enlarged mature tissue elements that originate in the area.

  
  

  Basically, these are normal structures bit they are just too big and unstructured.

  
• Name a commonmalignant tumor that arises from the epidermis.

  Squamous cell carcinoma
• What two things might induce a squamous cell carcinoma in the epidermis?

  - UV radiation

  - Papillomavirus infection (feline or equine)
• Follicular tumors are typically (benign/malignant)

  benign

  
• Where do perianal/hepatoid gland neoplasms arise from? Are they usually malignant or benign?

  Arise from adnexa

  
  

  Usually benign

  
• Which malignant tumor arises from the adnexa and can cause paraneoplastic hypercalcemia?


  Apocrine gland anal sac adenocarcinoma (AGASACA)
• Name common tumors that arises from the connective tissue. Are they malignant or benign?

  • lipoma
  • fibroma
  • soft tissue mesenchymal tumors/ sarcomas
  • feline injection-site sarcoma
• You do an FNA of a mobile subcutaneous mass on a lab and get sample with what appears to be lots of lipid. What is a Ddx and what is the prognosis for this Ddx?

  Lipoma, prognosis is usually very good
• There many types of soft tissue mesenchymal tumors/sarcomas (AKA soft tissue sarcomas) and they are often difficult to distinguish histologically. So how do we determine prognosis?

  There are two histologic grading schemes in dogs that have some prognostic value.

  
• Why do we give cats injections on distal limbs or the tail when possible?

  Injection-site sarcomas are highly locally aggressive

  
• Cutaneous ___-cell lymphoma is am epitheliotropic progressive, typically fatal neoplasm that usually occurs in older dogs.

  B

  
• What are the two grading schemes used for mast cell tumors?

  Grades I-III (Patnaik)

  Low vs. high grade (Kiupel)

  
• Give two Ddx for this cat

  - Mast cell tumor

  - Feline miliary dermatitis

  
• Give a Ddx for this neoplasm. Is this typically benign or malignant?

  Cutaneous plasmacytoma

  
  

  Typically benign

  
• Identify the neoplasm. Is it malignant or benign?

  Canine cutaneous histiocytoma

  
  

  Benign, should spontaneously regress.

  
• Name two types of vascular neoplasms: one that is malignant and one that is benign.

  Hemangioma - benign

  Hemangiosarcoma - malignant
• Identify the neoplasm. Can it metastasize?

  Canine cutaneous Langerhans cell histiocytosis - can spread to lymph nodes and internal organs

  
• What are the two transmissible tumors of the skin

  - Transmissible venereal tumor

  - Devil facial tumor disease
• Know which two cutaneous neoplasms are commonly solar-induced in animals

  - SCC

  - Hemangiomas/hemangiosarcomas
• Recognize which two common canine cutanous neoplasms have histologic grading schemes to suggest prognosis

  - Mast cell tumors

  - Soft tissue mesenchymal tumors/sarcomas