Week 6

Definitions

  • Neoplasia: An abnormal, uncontrolled cell growth.

    • Does not automatically indicate a harmful condition.

    • Subdivided into different classifications, such as benign and malignant neoplasia.

Types of Neoplasia

Benign Neoplasia

  • Remains localized at the primary site of growth (tumor or neoplastic mass).

  • Does not invade other tissues, exhibiting slow growth, and well-defined borders.

  • Potential Issues:

    • Can become large enough to impede structure or function, causing:

    • Compression.

    • Irritation.

    • Movement interference.

    • Pain.

  • Example: Lipoma: A benign fatty mass that can impact mobility (e.g., restricts a dog’s leg movement).

Malignant Neoplasia

  • Characterized by uncontrolled growth and potential for metastasis (spreading to distant sites).

  • Generally referred to as cancer, with metastasis typically occurring in organs such as:

    • Lungs.

    • Liver.

    • Spleen.

    • Brain.

    • Bone.

  • Method of Spread: Primarily through the bloodstream or lymphatic system.

Diagnostics

Importance of History and Physical Examination

  • Gathering the medical history of the pet is critical.

    • Signs may include:

    • Notable masses.

    • Changes in weight or appetite.

    • Signs of bleeding or discharge.

    • Difficulty in eating, breathing, urinating, or defecating.

    • Lameness, lethargy, or slow wound healing.

  • Physical Examination:

    • Palpate all superficial lymph nodes.

    • Record the location and size of any visible masses.

Diagnostic Tests

  • Common diagnostic tests include:

    • General blood panel.

    • Urinalysis.

    • Fine needle aspirate for cytology.

    • Biopsy.

    • Radiographs (chest and abdominal).

    • Ultrasound (chest and abdominal).

    • Bone marrow aspirate.

    • Specialized testing (e.g., OncoK9, Cadet).

Major Considerations in Diagnosis

  • Measure mass size using calipers for objective assessment.

  • Use the analogy of food sizes to communicate effectively, but quantify with rulers or calipers for accuracy to avoid misinterpretation of growth.

  • A reasonable time to reevaluate a mass is approximately three weeks; if it persists or grows, action should be taken.

Importance of Biopsy and Cytology

  • Fine Needle Aspiration (FNA):

    • Performed using a 22-gauge needle and a 6 mL syringe.

    • Techniques: Poke technique vs. suction technique (woodpecker method).

  • Potential Risk of Spreading Cancer:

    • Concerns regarding needle punctures causing inflammation or redistributing cancer cells; however, evidence does not strongly support this.

Malignancy Criteria

  • Parameters to assess for malignancy:

    • Anisocaryosis: Variation in nuclear size.

    • Macrokaryosis: Increased nuclear size.

    • Nuclear/Cytoplasmic Ratios: Increased ratios can indicate malignancy.

    • Nucleoli: May appear large and variable in shape.

    • Chromatin Patterns: Abnormal patterns and nuclear molding may be noted.

Cytoplasmic Indicators

  • Basophilia: Increased basophilic (blue-stained) cytoplasm.

  • Abnormal Vacuolarization: Presence of unusual vacuoles.

  • Watching for general criteria:

    • Anisocytosis: Variation in cell size.

    • Macrocytosis: Abnormally large cells.

Biopsy Techniques

Types of Biopsies

  • Needle Biopsy: Core or true cut - larger gauge needle for bigger samples (generally 14 to 16 gauge).

  • Incisional Biopsy: Cutting into a lesion to obtain a wedge of tissue for inspection.

  • Excisional Biopsy: Complete removal of the lesion, ideally with margins of normal tissue.

  • Importance of sending tissue samples for histopathological evaluation post-excision for accurate identification and treatment planning.

Treatment Approaches

Surgical Approaches

  • Primary goal may be curative; requires removing the malignant mass with adequate margins (1-2 inches of normal tissue preferred).

    • Importance of removing surrounding tissues to account for potential microscopic extensions of the tumor.

Other Treatments

Radiation Therapy

  • Disrupts DNA of neoplastic cells, typically used alongside other modalities, with careful dosage to minimize side effects.

Chemotherapy

  • Used for systemic cancers, aiming to induce remission rather than cure.

    • Side effects can include hair loss, cardiotoxicity, GI upset, and bone marrow suppression.

    • Animals often tolerate chemotherapy better than humans due to species differences in side effects.

Adjunctive Therapies

  • Typically address adverse effects from treatments like chemotherapy.

    • Example: Erythropoietin (Epogen) for combatting chemotherapy-induced anemia.

    • Nutrition is important, especially omega-3 fatty acids from fish oil that may support overall health during treatments.

Final Reflections

  • Personal anecdotes stress the unpredictability of tumor behavior, underlying the necessity of diligent follow-up and client education.

  • Importance of thorough diagnostics, biopsies, and ongoing communication with clients regarding treatment options and outcomes has been highlighted.