Small Animal Dermatology, 3rd edition

40 BASICS

TABLE 4.2. (Continued)

Hydropic degeneration Vacuolar damage to the stratum basale; frequently seen with discoid lupus

erythematosus

Hyper- and hypogranulosis Denotes thickness of stratum granulosum (e.g., areas of lichenification

reveal hypergranulosis)

Hyperkeratosis Increased thickness of stratum corneum layer of epidermis; divided into

orthokeratosis (nuclei lost) and parakeratosis (nuclei retained); assists in

identifying an etiology (e.g., zinc-responsive dermatosis is characterized by

parakeratosis)

Hypomelanosis Decrease in pigment; as seen in vitiligo

Melanosis Hyperpigmentation; seen in chronic inflammation

Microabscess, eosinophilic Seen in EGC, allergy, pemphigus complex, Malassezia, eosinophilic

folliculitis

Microabscess, Munro’s Accumulation of neutrophils within or below the stratum corneum; often

seen in psoriasiform lichenoid dermatosis of springers

Microabscess, Pautrier’s Accumulation of abnormal lymphoid cells; often seen in epitheliotropic

lymphoma

Microabscess, spongiform Accumulation of neutrophils within stratum spinosum often seen with

superficial suppurative necrolytic dermatitis of schnauzers

Mucinosis Increased amounts of amorphous basophilic material in the dermis;

characteristic of normal skin in the shar-pei dog and in hypothyroidism

Necrolysis Epidermal coagulative necrosis with no dermal involvement and minimal

inflammation; often seen with TEN and thermal burns

Papillomatosis Epidermal proliferation due to papilloma virus infection, often exophytic;

may be endophytic

Pigmentary incontinence Melanin pigment dropped from the epidermis into the dermis and

phagocytized by macrophages; often seen with DLE

Reticular degeneration Multilocular intraepidermal edema with keratinocyte swelling; often seen

with superficial necrolytic dermatitis/hepatocutaneous syndrome

Satellitosis Cytotoxic lymphocytes surrounding an apoptotic cell; indicates

cell-mediated immune response

Spongiosis Epidermal intercellular edema

Sclerosis Scar formation

Vacuolar degeneration Intracellular edema

DLE, discoid lupus erythematosus; EGC, eosinophilic granuloma complex; RBC, red blood cell; TEN, toxic epidermal
necrolysis; WBC, white blood cell.