Pathology Laboratory

Macule

circumscribed flat area of color change <1cm diameter.

Patch

circumscribed flat area of color change >1cm diameter.

Papule

solid elevated lesion <1cm diameter.

Plaque

flat elevation in skin >1cm.

Pustule

circumscribed elevation of skin containing pus; may be intraepidermal, subepidermal or follicular in location.

Vesicle

sharply circumscribed elevation of epidermis filled with clear fluid, <1cm diameter, intraepidermal or subepidermal

Bulla

sharply circumscribed elevation of epidermis filled with clear fluid, >1cm diameter.

Wheal

sharply circumscribed raised lesion consisting of edema

Nodule

circumscribed solid elevation >1cm in diameter that usually extends into deeper layers of skin

Cyst

epithelium-lined cavity containing fluid or a solid material. It is a smooth, well-circumscribed, fluctuant to solid mass.

Alopecia

complete loss of hair

Hypotrichosis

thin hair coat/partial loss of hair

Scale

accumulation of loose fragments of stratum corneum.

Crust

accumulation of dried exudate, serum, pus, blood, cells, or scales adherent to skin

surface

Follicular casts

accumulation of keratin and follicular material that adheres to hair shaft

extending above surface of follicular ostia.

Comedo

dilated hair follicle filled with cornified cells and sebaceous material

Pigmentary abnormalities

changes in skin color due to a variety of pigments or lack of

pigment such as melanin.

Epidermal collarette

special type of scale arranged in a circular rim of loose keratin flakes

or peeling keratin

Scar

area of fibrous tissue that has replaced damaged dermis or subcutaneous tissue

Excoriation

erosion or ulcer caused by scratching, biting, or rubbing

Erosion

shallow epidermal defect that does not penetrate basal laminar zone Ulcer: break

in continuity of epidermis with exposure of underlying dermis

Fissure

linear cleavage into epidermis or through epidermis into the dermis. May be single or multiple, curved, branching or straight

Lichenification

thickening and hardening of skin characterized by exaggeration of superficial skin markings. Often hyperpigmented. Hyperkeratosis is increased thickness of stratum corneum.

Callus

thickened, rough, hyperkeratotic, alopecic, often lichenified plaque

integument

It serves as the anatomic boundary between the body and the ambient environment.

epidermis

prime example of an adult tissue that undergoes continual and rapid flux. It also maintains homeostasis by constant proliferation of a single inner (basal) layer of rapidly dividing progeny of stem cells.

stratum basale (basal layer)

This is the deep germinative layer of the epidermis and is composed of a single layer of cuboidal to low columnar cells resting on the basement membrane zone.

stratum spinosum/prickle cell layer

This is characterized by prominent intercellular bridges that are the desmosomal attachments between cells.

stratum granulosum

variably apparent on light microscopy in haired skin and appears only 1-2 cells thick.

stratum corneum / SC

This is composed of >20 overlapping layers of bland, polyhedral, anucleate cells sandwiched between layers of lipid.

Melanocytes

These are located in the basal layer of the epidermis and outer root sheath of hair follicles; and in hematoxylin and eosin (H&E) sections, they appear as clear cells with a small dark-staining nucleus because of shrinkage artifact.

Acanthosis nigricans

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Lichenification

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Alopecia

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Hypotrichosis

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Cyst

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Excoriation: Ulcer and erosion

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Callus

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Lipomas

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Sebaceous Adenomas

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Dells

small depressions or hollows in the surface of the epidermis independent of adnexal structures. They are usually associated with focal epidermal atrophy and orthokeratotic hyperkeratosis. This term is not commonly used in veterinary dermatology

Epidermal collarette

a special type of loose scale that is arranged in a circular pattern around a central area of erythema or hyperpigmentation. Epidermal collarettes most likely represent ruptured pustules or papules from bacterial folliculitis.

Eschar

thick crust that forms in association with an ulcer and is tightly adherent to the skin because of the incorporation of dermal collagen (e.g., thermal burn).

Papules

are solid, circumscribed, elevations in the skin that are <1 cm in diameter. They can be follicular (e.g., stap­hylococcal folliculitis) or nonfollicular (e.g., flea-bite hypersensitivity).

Plaques

are solid, slightly raised elevations in the skin that are >1 cm in diameter (e.g., feline eosinophilic plaque).

Pustules

can be gross or microscopic accumulations in skin that are filled with inflammatory cells, usually neutrophils or eosinophils. It can be follicular or nonfollicular (e.g., superficial pemphigus).

Scale

refers to a flat plate of stratum corneum (e.g., Golden Retriever ichthyosis). It is important to distinguish scale versus crust on physical examination.

Wheal

a firm, circumscribed, raised elevation in the skin, composed of edema and is often erythematous (e.g., equine urticaria).

Hemimelia

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Umbilical Hernia

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Perineal hernia

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Diaphragmatic Hernia

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Inguinal Hernia

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Scrotal Hernia

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Hydranencephalus

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Hydrocephalus

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Kyphosis

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Microophthalmia

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Palatoschisis

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Cheiloschisis

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Perosomus elumbis

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Polydactyly

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Porencephaly

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Prognathia

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Syndactyly

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Alpha-mannosidosis

a rare, autosomal, recessively inherited lysosomal storage disease caused by a deficiency of the enzyme α-D-mannosidase1. This enzyme is involved in the digestion of complex sugars derived from glycoproteins, and a defective alphamannosidase leads to the progressive accumulation of mannose-rich oligosaccharides in all tissues

Thoracoschisis

rare congenital malformation characterized by herniation of intraabdominal contents through a thoracic wall defect.

C3 deficiency

It makes an individual susceptible to severe, recurrent infections from encapsulated bacteria.

Hemophilia B

a bleeding disorder caused by a deficiency of Factor IX, a protein necessary for blood coagulation

Pyruvate kinase deficiency

an inherited metabolic disorder of the enzyme pyruvate kinase which affects the survival of red blood cells.

Von Willebrand disease (VWD)

the most common hereditary blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions.

Chédiak–Higashi syndrome / CHS

s a rare autosomal recessive disorder that arises from a mutation of a lysosomal trafficking regulator protein, which leads to a decrease in phagocytosis. The decrease in phagocytosis results in recurrent pyogenic infections, albinism, and peripheral neuropathy

Citrullinemia

an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood.

Ehlers–Danlos syndromes (EDS)

group of 13 genetic connective-tissue disorders. Symptoms often include loose joints, joint pain, stretchy velvety skin, and abnormal scar formation.

Photoporphyria

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Glycogen storage disease

Glycogen is a polymer of glucose needed to provide for a continuous source of glucose during fasting. Glycogen synthesis and degradation are tightly controlled by complex regulatory mechanisms and any disturbance in this regulation can lead to an inadequate reservoir of glycogen or an accumulation of excess or abnormal glycogen stored either in the cytosol or in the lysosomes

Malignant hyperthermia (MH)

a potentially fatal pharmacogenetic disorder of skeletal muscle calcium regulation. Triggered by exposure to certain drugs or stressors, clinical signs include sudden and dramatic rise in body temperature, muscle fasciculation, muscle rigidity, tachypnea, tachycardia, arrhythmia, myoglobinuria, metabolic acidosis, renal failure, and death.