autoimmune diseases with Drs Petersen and Noland

Introduction

• Diagnosis and Management of Autoimmune/Immune-mediated Diseases

  • Erica Noland, DVM, Dip ACVP (Dermatopathologist)

  • Annette Petersen, Dr.med.vet.; Dip ACVD (Associate Professor of Dermatology)

Outline

• Key Topics Covered

  • Cutaneous Lupus Erythematosus

    • Clinical focus on Discoid Lupus Erythematosus

  • Pemphigus Complex

    • Clinical focus on Pemphigus foliaceous

  • Erythema Multiforme/Toxic Epidermal Necrolysis

Cutaneous Lupus Erythematosus (CLE)

• Overview

  • Immune-mediated skin condition

  • Forms:

    • Localized form (Discoid CLE)

    • Generalized form

  • Breed-Specific Forms:

    • Exfoliative cutaneous lupus erythematosus (German Shorthaired Pointer)

    • Vesicular cutaneous lupus erythematosus (Rough-coated Collies, Shetland Sheepdogs, Border Collies)

Classification

• According to Olivry et al. (2018)

  • Examples in dogs:

    • Lupus-specific: Interface pattern with basal vacuolation/apoptosis

    • Lupus non-specific: Vasculitis

Discoid Lupus Erythematosus (DLE)

• Characteristics

  • Absence of systemic involvement

  • Photo-induced skin disease: UV light affects basal keratinocytes

  • Altered keratinocyte surface antigens lead to autoantibody production

  • Immune complexes form in dermis

Histopathology

• Histologic overlap observed in lesions

  • Mucous membranes react to chronic injury with lymphoplasmacytic inflammation in the lichenoid band

  • Some DLE cases may represent generalized reactions to injury rather than specific autoimmune disorders

Diagnosing DLE

• Histopathological examination should be complemented with clinical findings

• Clinical Signs:

  • Loss of cobblestone architecture, depigmentation, erosion/ulcers, crusts

  • Histopathology: Lymphoplasmacytic lichenoid dermatitis

  • Lack of response to antimicrobial therapy

Clinical Lesions of DLE

• Location: periorbital region, ears, nose (rarely inguinal area)

  • Lesions:

    • Depigmentation, erythema, erosions, ulcers

    • Loss of cobblestone architecture leads to smooth surface and potential scarring

Treatment Options for DLE

• Medications:

  • Topical Tacrolimus (ProTopic®): Calcineurin inhibitor

  • Doxycycline: Suppresses chemotaxis of neutrophils

  • Niacinamide: Blocks IgE-mediated histamine release

  • Vitamin E: Antioxidant properties

  • Topical glucocorticoids: Reduce inflammation

  • UV light avoidance: Especially 10 AM - 4 PM

  • Daily sunscreen application: Non-zinc formulas for nasal lesions

Mucocutaneous Pyoderma

• Characteristics

  • Affects lips and perioral skin

  • Symptoms: swelling, erythema, crusting, fissures

  • Differentiation: Lesions on nasal planum are not affected in pyoderma

Pemphigus Complex

• Overview

  • Rare autoimmune diseases characterized by papular-pustular or vesicular-bullous lesions

  • Including Pemphigus foliaceus (most common) and Pemphigus vulgaris (least common)

Pathogenesis of Pemphigus

• Desmosomes connecting cells to one another

  • Composed of proteins: Cadherins, Desmocollin, Desmoglein, Keratin filaments

Pemphigus Foliaceus: Clinical Features

• Pustules: Transient and rapidly rupture

• Symptoms: Alopecia, erosions, crusts, epidermal collarettes

• Affects nose, muzzle, periorbital region, pinnae, footpads, genital region

Pemphigus Vulgaris

• Characteristics

  • Severe form of pemphigus

  • Symptoms: transient vesicles, bullae, erosions, and ulcers

  • Strong association with oral mucosal lesions

Erythema Multiforme

• Overview: Inflammatory disease with cutaneous/mucocutaneous lesions

  • Cytotoxic reaction pattern

  • Commonly associated with drug reactions, infections, and neoplasia

• Clinical Signs: Erythematous macules, target lesions, vesicles, bullae

Toxic Epidermal Necrolysis (TEN)

• Severe form of erythema multiforme

• Symptoms: Massive apoptosis, extensive loss of epidermis, painful lesions

Diagnosis and Treatment Considerations

• Assessment of drug exposure and CBC for infectious disease

• Treatment: Supportive therapy, potential immunosuppressive drugs in severe cases

  • Avoidance of drugs that may have caused the reaction

  • Best practices include careful diagnosis to avoid unnecessary harm.