2. Causes of disease - Part 1

What does "3D ATP" stand for in morphologic diagnosis?

"3D ATP" refers to Tissue & Process (Inflammatory, Degenerative, Disorders of Growth), Best Adjective, and Degree, Duration, Distribution.

What is a morphologic diagnosis, and what does it involve?

A morphologic diagnosis is a lesion diagnosis based on the predominant lesions in the tissues, addressing macroscopic and microscopic aspects, including degree, duration, distribution, location, and nature of the lesion.

Describe the components of "ATP" in morphologic diagnosis.

ATP" includes Adjective (e.g., hemorrhagic, suppurative), and "3D" includes Degree (mild, moderate, marked), Duration (peracute, acute, subacute, chronic), and Distribution (focal, multifocal, locally or regionally extensive, disseminated, diffuse).

What is an etiologic diagnosis, and what elements does it indicate?

An etiologic diagnosis indicates the cause of a disease and includes two elements: cause and tissue process.

What does biliary imbibition represent in a necropsy, and what kind of change does it represent?

Biliary imbibition is due to bile leakage after death and represents a post-mortem artifact.

What does a clinical diagnosis involve, and how is it usually supplemented?

Clinical diagnosis involves data from case history, signs/symptoms, and physical examination. It suggests the system involved and is supplemented by a list of differential diagnoses.

What is clinico-pathologic diagnosis, and what does it involve?

Clinico-pathologic diagnosis is based on changes observed in the chemistry of fluids and the structure/function of cells collected from the living or dead patient, including smears, aspirates, and biopsies.

What elements are addressed in morphologic diagnosis, including examples of the nature of lesions?

Degree/severity, duration, distribution, location, and nature of the lesion (process) such as degenerative, inflammatory, neoplastic.

What is a diagnosis, and what are its limitations in terms of accuracy?

Diagnosis is a concise conclusion about the nature, cause, or name of a disease based on careful investigation. Accuracy is limited by the history provided and the available evidence (lesions).

What are the components of disease, including factors such as host factors, environmental factors, and characteristics specific to the injurious agent?

Disease components include host factors, environmental factors, and characteristics specific to the injurious agent.

Provide examples and differentiate between endogenous and exogenous causes of disease.

Endogenous causes originate from within the organism (e.g., genetic factors), while exogenous causes come from external sources (e.g., infections, toxins).

Define etiologic differential diagnosis, and provide examples.

Etiologic differential diagnosis involves agents/processes causing similar lesions. Examples include Mannheimia haemolytica infection ("mannheimiosis"), Pasteurella multocida, and Mycoplasma mycoides.

Define etiology and list some components studied in the science of causation.

Etiology is the study of causation, including infectious agents (bacteria, viruses, parasites, fungi), genetics, trauma, nutrition, and environmental factors.

Provide examples of etiologic diagnoses.

Examples include "bacterial pneumonia," "viral pneumonia," and "toxic pneumonia." E.g., "pneumonic mannheimiosis" or "Mannheimia haemolytica pneumonia."

What are some contributing factors of disease related to disposition, age, and constitution?

Factors include genetic disposition, species/breed/family/sex/individual disposition, acquired disposition, nutrition, occupation, age, constitution, and condition.

List examples of endogenous (intrinsic) causes of disease.

Genetic diseases, certain malformations, and immunologic factors.

How do genetic factors play a role in disease processes?

Genetic factors can influence susceptibility, progression, and manifestation of diseases.

What is the morphologic diagnosis when observing multiple masses on the spleen, described as variably sized, round to irregular, dark red to tan, well-demarcated nodules?

Hemangiosarcoma

What does interpretive diagnosis involve, and what does it lead to?

Interpretive diagnosis uses all available knowledge, plays the odds, leads to ranked differential diagnoses, and results in a logical, defined diagnostic plan.

What are the two types of morphologic diagnoses, and what levels do they address?

Macroscopic morphologic diagnosis is at the gross level, while microscopic morphologic diagnosis is at the light microscopy level.

How do you formulate morphologic and etiologic diagnoses?

Morphologic diagnoses involve describing lesions using the CLASS-C approach, while etiologic diagnoses focus on identifying the cause of the disease.

Define morphologic differential diagnoses and provide an example.

Morphologic differential diagnoses involve lesions that look similar, such as acute suppurative/fibrinous bronchopneumonia vs. acute aspiration pneumonia.

When can mutations in DNA occur?

Mutations can occur spontaneously or can be caused by environmental factors (UV light, ion radiation, temperature, chemicals, viruses, etc.

What is pathogenesis, and how can you differentiate between various types of diagnoses?

Pathogenesis is the development of a disease, and diagnoses can be differentiated by considering morphologic and etiologic aspects.

Define pathogenesis in the context of disease.

Pathogenesis refers to the mechanisms of disease, representing the sequence of events from initial stimulus to resolution, involving suffering (pathos) and origin (genesis).

How common is the perpetuation of DNA mutations?

Perpetuation of DNA mutations is relatively rare due to cellular DNA repair mechanisms

List examples of exogenous ("extrinsic"/"acquired") causes of disease.

Physical noxious stimuli ("noxes") such as: (traumatic, thermal, actinic, electric, climatic) - Chemical noxes/toxins - Alimentary/nutritional causes - Infectious organisms

Explain the mechanism that leads to massive hemorrhage and potential death in hemangiosarcoma.

Rupture of nodules on the spleen results in massive hemorrhage into the abdomen (hemoabdomen).

What is the CLASS-C approach, and how is it used to describe various lesions?

The CLASS-C approach involves finding the lesion, describing it, recognizing the basic process, explaining the mechanism, considering causative agents, environmental factors, and host factors.

What percentage of human diseases can be attributed to genetic causes, and how are mutations passed on?

Up to 70% of human diseases can have genetic causes. Mutations in germline cells have the potential to be inheritable.

How is pathology knowledge used in detecting diseases, forming a diagnostic strategy, and reaching a definitive diagnosis?

Visual cues are interpreted to detect the disease process, leading to a diagnostic strategy and, hopefully, a specific therapy.