Pathology Exam 4 – Recap (Key Terminology)

Vocabulary-style flashcards covering necropsy basics, integumentary pathologies, and respiratory system terms from the lecture notes.

The standard tissue fixative used in histopathology.

10% Neutral Buffered Formalin

Fixation ratio

Volume of formalin to tissue should be at least 10 parts formalin to 1 part tissue.

Tissue thickness limit for fixation

Maximum tissue thickness of about 1 cm (5–10 mm) to ensure adequate formalin penetration; brain may be fixed whole.

Formalin penetration time

Formalin can penetrate 1 cm of tissue in 24 hours at room temperature.

Fixative used for electron microscopy, not common in routine practice.

Glutaraldehyde

Fixative used for eyes, endocrine tissues, and viral inclusion bodies; less commonly used today.

Bouin's fixative

Carcass identification methods

Microchip, brands/marks, and weighing to prove identity for legal necropsies.

Agonal changes

Physiological changes at or near death, such as tracheal froth and certain emphysematous changes.

Agonal changes after barbiturate euthanasia

Tracheal froth can be an expected agonal change; barbiturate overdose may also cause sleepy scavengers/predators.

Lung color as death indicator

Darker lung on the down side (more pooling of blood); paler lung on the up side (less blood).

Necropsy identification procedures (ID)

External carcass identification, systemic sampling, and proper documentation for legal cases.

Plan early to collect sterile samples (fluids and tissues) to prevent this type of contamination.

Pseudolesions during necropsy sampling

Sterile sample types for necropsy

Urine, peritoneal/thoracic/pericardial fluids, bile, liver, spleen, kidney, lung, brain, bone marrow.

RNA and DNA handling for necropsy

RNA is labile and stored at -80°C with RNase inhibitors; DNA is more stable and can be stored at -20°C or -80°C.

Pneumothorax assessment technique

Puncture the diaphragm and observe chest cavity changes and air influx to determine presence/absence of pneumothorax.

Anthrax handling

Do not open the carcass; exposure can form resistant spores. Collect blood for Gram staining and notify government veterinarians.

Legal necropsies

Require thorough chain-of-evidence documentation, carcass identity proof, limited participants, and readiness to testify.

Safe necropsy practices

Safe sharps handling, proper waste disposal, ventilation, keeping formalin lids on, and avoiding splashes.

Early sample collection rationale

Collect sterile samples early to avoid contamination and preserve sample integrity.

Common necropsy samples for toxins

Adipose tissue for fat-soluble toxins; urine, liver, kidney, stomach contents for water-soluble toxins.

Folliculitis

Inflammation of hair follicles.

Alopecia

Hair loss or thinning; types include hypotrichosis, scarring alopecia, alopecia areata, recurrent flank alopecia.

Ichthyosis

Generalized scaling due to congenital/hereditary disorder of stratum corneum formation.

Cutaneous asthenia/dermatosparaxis

Hereditary collagen dysplasia with stretchy, fragile skin (Rubber Puppy Syndrome).

Epitheliogenesis imperfecta

Congenital failure of skin formation leading to missing skin patches.

Alopecia X

Symmetrical trunk, perineum, thighs, and neck alopecia in some dog breeds; head/extremities spared.

Discoid lupus erythematosus (DLE)

Autoimmune disease affecting the nasal planum with depigmentation, erosion, and hyperkeratosis.

Poxvirus inclusion bodies

Intracytoplasmic inclusion bodies typical of poxviruses.

Papillomavirus histology

Intranuclear inclusion bodies and koilocytes.

Distemper histology

Syncytial cells with intranuclear and/or intracytoplasmic inclusion bodies; hardpad in dogs.

Dermatophytosis

Fungal skin infection (ringworm); endothrix or ectothrix involvement; diagnosed by culture, cytology, histopathology, PCR; Woods lamp may aid M. canis.

Dermatophilosis

Dermatophilus congolensis infection; also called rain rot/streptothricosis; zoonotic.

Miliary dermatitis

Multifocal small raised red lesions often due to flea bite hypersensitivity.

Purpura hemorrhagica

Immune-mediated vasculitis in horses post-Streptococcus equi exposure.

Alabama rot (CRGV)

Cutaneous and renal glomerular vasculopathy in dogs with unknown etiology.

PDNS

Porcine dermatopathy & nephropathy syndrome; vascular lesions associated with Porcine circovirus 2.

SPGS

Sterile Pyogranuloma Syndrome; sterile inflammatory skin condition with perifollicular granulomas.

Sterile Nodular Panniculitis (SNP)

Sterile inflammation of subcutaneous fat; sometimes linked to pancreatic disease.

Plasma cell pododermatitis

Immune-mediated inflamed paw pads causing swelling and soft tissue changes.

Feline lung-digit syndrome

Primary pulmonary adenocarcinomas in cats metastasizing to digits (skin, subcutis, bone).

Onychitis

Inflammation of the nail bed.

Sarcoptic mange

Mite-induced mange causing intense pruritus and epidermal changes.

Nude mouse immunodeficiency

Genetic mutation of FoxN1 causing thymic hypoplasia and lack of T-cells.

Cutaneous mucinosis of Shar-Peis

Overproduction of hyaluronic acid leading to wrinkles and delayed wound healing.

Acromelanism

Temperature-dependent coat color with thermally unstable tyrosinase; darker in cold areas.

Sebaceous adenitis

Autoimmune destruction of sebaceous glands leading to dry, brittle hair.

Calcinosis cutis/circumscripta

Mineral deposits in the skin; diffuse/plaque-like (cutis) vs localized (circumscripta).

Actinic dermatopathies

Sun-related skin diseases: solar dermatitis, solar elastosis, solar keratoses, squamous cell carcinoma.

Photosensitisation types I-III

Type I: photodynamic reacting substances; Type II: porphyria; Type III: hepatogenous photosensitisation due to phylloerythrin buildup.

Atopic dermatitis

IgE-mediated allergic skin disease to environmental allergens.

Hyperadrenocorticism (Cushing's) dermatopathies

Endocrine skin changes including orthokeratotic hyperkeratosis and trunk hypotrichosis; calcinosis cutis common.

Hypothyroidism dermatopathies

Dry, coarse hair, hyperpigmentation, hair loss with conditions like myxoedema.

Hyperoestrogenism dermatopathies

Symmetric alopecia with skin hyperpigmentation; secondary to ovarian/testicular neoplasia or estrogen exposure.

Winged terms: wound healing stages

Crust formation, epidermal hyperplasia, granulation tissue formation, scar formation with contraction.

Nutritional dermatopathies

Deficiencies include protein-calorie deficiency, fatty acids, vitamins A/C/E, and zinc.

IgE-mediated dermatopathies

Atopy, urticaria, and angioedema; Type I hypersensitivity with IgE.

EM-SJS-TEN spectrum

Erythema multiforme (EM) to Stevens-Johnson syndrome (SJS) to Toxic Epidermal Necrolysis (TEN); increasing severity with cytotoxic keratinocyte death.

Drug eruptions

Drug-induced skin reactions that can mimic other dermatopathies.

Margin inking and fixation of skin samples

Techniques to define excision margins for pathologic confirmation of complete tumor removal.

Paraneoplastic dermatopathies

Skin manifestations associated with internal neoplasia (e.g., thymoma, hepatocutaneous syndrome).

Ctenocephalides vs Echidnophaga fleas

Ctenocephalides canis: mobile dog/cat flea; Echidnophaga gallinacea: stickfast flea often around chicken eyelids.

Petechiae vs diamond skin disease

Petechiae are small hemorrhages; diamond skin disease shows multifocal polygonal cutaneous infarcts from erysipelothrix rhusiopathiae in pigs.

Dermoid, follicular and apocrine cysts

Benign lumps: dermoid (congenital with skin/adnexal structures), follicular (keratin-filled), apocrine (gland with clear fluid).

Comedones

Blackheads from plugged follicles; Schnauzer comedo syndrome is a breed example.

Sebaceous hyperplasia

Benign overgrowth of sebaceous glands.

Calcinosis cutis vs circumscripta

Calcinosis cutis: diffuse/plaque-like mineral deposits; circumscripta: localized mineral deposits around joints.

Lipomas and infiltrative lipomas

Benign fat tumors; infiltrative lipomas invade surrounding tissues and have poorer prognosis.

Round cell skin neoplasms

Common canine: histiocytoma, plasmacytoma, mast cell tumor, lymphoma; feline: mast cell tumor, lymphoma.

Margin inking and FISS (Feline Injection Site Sarcoma)

Techniques to define tumor margins; FISS is a vaccination-associated sarcoma in cats.

Paraneoplastic dermatopathies examples

Skin changes caused by underlying neoplasia (e.g., thymoma-associated exfoliative dermatitis).

Inflammation of respective nasal and airway structures.

Rhinologic terms: rhinitis, sinusitis, laryngitis, tracheitis, bronchitis, bronchiolitis

Progressive ethmoidal hematoma

Unilateral nasal growth causing epistaxis in horses.

Guttural pouch diseases

Empyema (pus), mycosis (Aspergillus), tympany (air entrainment) in guttural pouches.

Kennel cough (CIRD)

Multifactorial respiratory disease with viral and bacterial components causing a dry cough.

Fat embolism

Fat droplets from shattered bones travel to lungs causing embolic obstruction.

ARDS

Acute Respiratory Distress Syndrome with diffuse alveolar damage and hypoxemia.

Pumice lung

Mineralized/brittle lung from metastatic calcification in hypercalcemia.

Aspiration pneumonia

Pneumonia from inhaled material; often polymicrobial with anaerobes.

Interstitial pneumonia

Diffuse involvement of lung parenchyma with firm, elastic tissue; often viral/toxic or hematogenous.

Verminous pneumonia

Pneumonia caused by parasitic worms (e.g., Dictyocaulus, Oslerus, Syngamus).

Granulomatous pneumonia

Firm nodules with caseous exudate; often due to Mycobacteria, fungi, parasites, or foreign material.

Dimorphic fungi

Fungi with yeast and mold forms (e.g., Cryptococcus, Blastomyces, Histoplasma, Coccidioides) causing systemic mycoses.

IHC marker TTF-1

Thyroid transcription factor 1; positivity supports primary pulmonary (bronchioloalveolar) adenocarcinoma.

Jaagsiekte (Ovine Pulmonary Adenocarcinoma)

Retrovirus-induced neoplasm in sheep affecting type 2 pneumocytes and Clara cells; heavy, wet lungs with frothy surfactant.

Enzootic nasal tumour (ENTV)

Carcinoma arising from ethmoid turbinates in small ruminants due to ENTV; causes respiratory distress and nasal discharge.

Enzootic nasal tumour virus (ENTV) and Jaagsiekte viruses

Retroviruses causing distinct pulmonary or nasal neoplasms in different species.

Pneumo-hydro- chylothorax terminology

Fluid/gas accumulation in the thoracic cavity: pneumothorax, hydrothorax, haemothorax, chylothorax, pyothorax.

Pneumothorax

Gas in the thoracic cavity causing lung collapse.

Hydrothorax

Transudate in the pleural cavity, often from heart failure or hypoproteinemia.

Hemothorax

Blood in the pleural cavity due to trauma or coagulopathy.

Chylothorax

Milky pleural effusion rich in lymph and lipids from lymphatic leakage; diagnose with triglycerides in effusion vs serum.

Pyothorax

Pus in the pleural cavity, often from penetrating trauma or spread from pulmonary infection.

Pleuritis

Inflammation of the pleura, potentially leading to fibrous or fibrinous adhesions.