Small Animal Dermatology, 3rd edition

676 DISEASES/DISORDERS

Single or multiple, proliferative tumors have a cauliflower appearance that is

friable and bleeds easily (Figures 46.6, 46.7)

Most common sites: cats – nasal planum, eyelids, lips, and pinnae; dogs – digits,

scrotum, nose, legs, and anus

Digital lesions are typically swollen and painful and have a misshapen or absent

claw

Lesions may also be found in the oral cavity, cornea, lungs, esophagus, and uri-

nary bladder.

 Melanocytic tumors:
85% of melanomas are benign
Benign, locally invasive, or metastatic (bone, lung, regional lymph nodes)
Pigmented or nonpigmented
Benign tumors are typically brown macules, plaques, or dome-shaped nodules

that are well circumscribed and less than 2 cm diameter (Figure 46.8)

Malignant melanomas are rapidly growing, nonpigmented to black, ulcerated or

pedunculated masses or nodules that are usually greater than 2 cm in diameter

(Figure 46.9, 46.10)

Most common on the head, trunk, and digits but may occur anywhere on the

body (most common on the head of cats)

More common in male dogs.

 Basal cell tumors:
Typically manifest as a solitary, well-circumscribed firm to fluctuant nodule; 1–

10 cm diameter (Figure 46.11)

Often alopecic, may be pigmented, and may be ulcerative (Figure 46.12)

Lesions most commonly found on the head (lip, cheek, pinnae, periocular),

neck, thorax, dorsal trunk

Feline basal cell carcinomas are highly metastatic

Canine malignant forms are rare; locally invasive; rarely metastasize.

 Sebaceous gland tumors:
Adenoma/hyperplasia: distinctive wart-like or cauliflower appearance in most

cases (Figures 46.13–46.16)

Adenocarcinomas: firm raised nodules that ulcerate; may have metastasized from

a primary bronchogenic site to the digits; in cats, swelling of multiple digits may

occur due to multicentric ungual metastasis, solitary metastasis is more common

than multicentric in dogs (Figures 46.17, 46.18)

Most common sites: cats – head, eyelids, extremities; dogs – head, neck, trunk,

legs, and eyelids

Few millimeters to several centimeters in diameter, typically multiple in number

Yellow in color, alopecic, oily, may ulcerate; may become traumatized

Adenocarcinomas are usually solitary, alopecic, ulcerated, or erythematous intra-

dermal nodules.

 Hair follicle tumors:
Single to multiple, alopecic, firm, white to gray multilobulated nodules that may

ulcerate; typically well circumscribed (Figures 46.19–46.23)

Location: head, tail, trunk, limbs