618 DISEASES/DISORDERS
Feline thymoma-associated exfoliative dermatitis:
Middle-aged to older cats
No breed or sex predilection.CLINICAL FEATURES
Canine preneoplastic dermatoses:
Actinic keratoses:
Lesions develop in sun-exposed lightly pigmented or unpigmented skin
(naturally or scarred) in areas not sufficiently protected by hair, and in junc-
tions between haired and nonhaired skin.
Nasal planum, dorsal muzzle, axillae, and glabrous areas of the ventral
abdomen and medial thigh
Early erythematous patches appear slightly lichenified or roughened
Epithelial plaques may be palpable as firm thickenings before becoming
visible and may be distinguishable from nonthickened (normal) adjacent
pigmented skin
Crusted, indurated, and exfoliating plaques (Figure 41.1)
Severe hyperkeratosis may be seen as cutaneous horns
Individual plaques and nodules (often with actinic comedones) coalesce to
larger lesions
Affected areas become extensive; inflammation and exudation develop with
secondary furunculosis
Axillae, ventral abdomen, and medial thigh primary sites; less often dorsal
muzzle and eyelid margin
Cutaneous lymphocytosis:
Patches of erythema or erythematous plaques on head, neck, thorax, and
axillae (Figure 41.2)
Multiple lesions
Slow progression without regression; potential to progress to high-grade
lymphoma
Rarely pruritic
Cutaneous mastocytosis:
Cutaneous lesions in dogs similar to urticaria pigmentosa of human
beings
Small erythematous macules, papules or plaques, wheals, and hemorrhagic
bullae on the head, neck, trunk, and legs
Manipulation induces erythema and induration
Nonmalignant conditions are more likely to have multiple lesions as
opposed to a single, discrete neoplasm
Nodular fasciitis:Solitary, subcutaneous mass often less than 2 cm in diameter
Predilection for the head, face, and eyelids.