Secondary Lesions

Question 1

Epidermal collarette

Answer 1

Circular rim of scaling around alopecic lesion
Originated initially from bulla or pustule that expanded outward.

Most commonly due to bacterial pyoderma

Less common from dermatophytes, insect bites, immune diseases.

Question 2

Excoriation

Answer 2

Erosion or ulceration caused by chewing, scratching (self trauma)

Common causes:
Ectoparasites
Hypersensitivity dermatitis (food, atopy, contact)
Secondary bacteria or yeast infections

Question 3

Erosions

Answer 3

Shallow epidermal defect that does not expose dermis.

Common causes by same causes of excoriations, ruptured vehicle caused by immune mediated disease.

Question 4

Ulcer

Answer 4

Epidermal defect with exposure of dermis

Common causes:

1) deep infection - bacteria or fungal
2) feline indolent ulcer
3) chemical burn or thermal burn
4) immune mediated disease
5) over a mass or granuloma - foreign bound neoplasia

Question 5

Lichenification

Answer 5

Thickened elephant skin

Often but not always hyperpigmented.

Common causes: Signifies chronic inflammation due to friction or chronic bacteria, hypersensitivity dermatitis, endocrinopathy or keratinization disorder.

Question 6

Callus

Answer 6

Non inflammatory hyperplastic response of skin causing thickening and hair loss

Most common on pressure points - elbows and hocks, ventral sternum, hips
May become secondarily infected

Question 7

Fissure

Answer 7

Linear cleave through epidermis +/- into dermis

Thick, inelastic or crusted skin or paws subjection to inflammation or friction/trauma.

Often occurs on paw pads, nasal planum, pinnae margins, oral and anal mucocutaneous borders.