Comprehensive Guide to Gross Pathology Description and the SALT Framework

Foundations of Gross Pathology and Diagnostic Description

• Role of Gross Pathology in Clinical Diagnosis:

  • Gross pathology refers to the identification and description of lesions using the naked eye.

  • It serves as the initial, critical step in diagnostic medicine across pathology, necropsy, surgical procedures, and clinical veterinary practice.

  • A complete and accurate gross description allows a clinician or surgeon who has not seen the specimen to visualize the exact alteration based solely on the written text.

• Sequential Steps in Lesion Evaluation:

  • Identify the specific organ or tissue type.

  • Identify the presence of any structural or visual abnormality within that tissue.

  • Systematically describe the abnormality using objective non-diagnostic terminology.

• Diagnostic Pathways Based on Etiological Knowledge:

  • When the disease cause is known:

  • The sequence of understanding follows: Etiology (Cause) $\rightarrow$ Pathogenesis (Mechanisms inside the body) $\rightarrow$ Morphological Lesions (Gross and microscopic) $\rightarrow$ Clinical Significance and Sequelae (Consequences).

  • When the disease cause is unknown (e.g., Necropsy):

  • The sequence begins with the observed physical changes: Morphological Changes / Gross Description $\rightarrow$ Tissue Sampling (for Histopathology, Microbiology, Parasitology) $\rightarrow$ Morphological / Etiological Diagnosis $\rightarrow$ Elucidation of Etiology and Pathogenesis.

• Definition of a Lesion:

  • A lesion is defined as any structural alteration in cells or tissues, or any damage/abnormal change that can be objectively identified.

  • Macroscopic / Gross Lesions: Alterations identifiable by the naked eye during gross examination or necropsy.

  • Microscopic Lesions: Alterations identified under light or electron microscopy in a histopathology laboratory.

The SALT Description Checklist

• Overview of the SALT Framework:

  • The SALT checklist is a simple, standardized tool designed to structure gross pathological descriptions without relying prematurely on medical or diagnostic terminology.

• Checklist Components:

  • S — Site, Size, Shape.

  • A — Appearance (including Color, Color Pattern, Surface, Margin, Cut Surface, and Contents).

  • L — Lesion Distribution and Lesion Extent.

  • T — Texture / Picture (Consistency).

Site, Size, and Shape (S)

• Site (Anatomical Location):

  • Identifies the organ or tissue type involved (e.g., liver, kidney, lung, intestine, cerebrum).

  • Specifies the precise location within the organ:

  • Anatomical landmarks: Cranial pole of the liver, capsular surface of the kidney, pleural surface of the lung, mucosa of the intestine, white matter of the cerebrum.

  • Sub-regions: Whole lobe vs. segment, cortex vs. medulla, serosal/neural surface vs. muscle vs. lumen.

  • Depth and directional orientation: Superficial vs. deep, caudal, cranial, ventral, lateral.

• Size (Quantitative Measurement):

  • Quantifies the magnitude of the lesion using standard metric units: millimeters ($\text{mm}$) or centimeters ($\text{cm}$).

  • For solitary round lesions, measure the diameter.

  • For multiple nodular or variable lesions, measure the smallest lesion and the largest lesion to record a size range.

  • Evaluation of overall organ enlargement or atrophy:

  • Border geometry: Normal sharp borders becoming rounded indicates organ enlargement.

  • Asymmetry in paired organs: Comparing bilateral organs (e.g., two kidneys) to determine relative enlargement or atrophy.

• Shape (Geometric Classification):

  • Uses strict geometric terms to define the two-dimensional outline:

  • Round

  • Oval

  • Irregular

  • Wedge-shaped

  • Linear

  • Nodular

  • Plaque-like

  • Note: Structural elevations (e.g., raised, flat, depressed) are excluded from the shape category and categorized under Appearance.

Appearance: Color, Surface, Margin, and Cut Section (A)

• Color Identification:

  • Must use clear, standard visual terms: bright red, dark red, pink, pale white, cream, tan, gray, yellow, green, brown, black, dark purple.

  • Vague or subjective descriptions (e.g., "adult-like color") must be strictly avoided.

  • Descriptive neutrality: Avoid jumping to diagnostic inferences (e.g., describing a red area as "hemorrhage" or "congestion" during the descriptive phase is prohibited).

• Color Patterns:

  • Mottled: Presence of two or more distinct colors interspersed within the same organ or tissue.

  • Streaked / Striped / Variegated: Color distribution showing linear bands or distinct varied streaks.

  • Stippled: Color distribution showing fine dots or small spots.

• Surface Character:

  • Smooth, rough, granular, nodular, corrugated, or striated.

• Margin and Profile:

  • Demarcation: Well-demarcated (a clear, distinct boundary separating healthy and diseased tissue) vs. poorly demarcated (a gradual, ill-defined transition).

  • Profile / Elevation:

  • Raised (elevated above the surrounding tissue plane).

  • Flat (level with the surrounding tissue plane).

  • Depressed (sunken below the surrounding tissue plane).

  • Umbilicated (depressed specifically in the center, resembling an umbilicus).

• Cut Surface and Internal Contents:

  • Evaluation of internal structures exposed upon sectioning (e.g., presence of single or multiple cystic structures, depth of tissue involvement, and nature of luminal or fluid contents).

Lesion Distribution and Extent (L)

• Lesion Distribution (Spatial Pattern):

  • Focal: A single, solitary, isolated lesion within the organ.

  • Multifocal: Multiple distinct, separate lesions scattered throughout the tissue.

  • Multifocal to Coalescing: Multiple distinct lesions growing together and merging into larger irregular areas.

  • Locally Extensive: A single, large, contiguous area of tissue affected by the lesion.

  • Diffuse: Homogeneous involvement affecting the entirety ($100\%$) of the organ or tissue.

• Lesion Extent (Quantitative Percentage):

  • Represents the estimated proportion or percentage of the total organ affected by the pathological process (e.g., a locally extensive lesion affecting $80\%$ of the organ).

  • Distinction: Pattern describes how lesions are arranged spatially; extent describes how much of the organ total is affected.

Texture and Consistency (T)

• Tactile Assessment Terms:

  • Soft: Anatomical tactile equivalent to touching one's cheek.

  • Firm: Anatomical tactile equivalent to touching the bridge of one's nose.

  • Hard: Anatomical tactile equivalent to touching one's forehead.

  • Additional specific texture descriptors: Friable (easily crumbled), gritty, rubbery, spongy, fluctuant (wave-like fluid feel), crepitant (crackling sensation due to trapped gas).

• Rule of Visual Assessment:

  • If evaluating photographical records or static images where tactile assessment is impossible, texture/consistency must not be guessed or invented; it must be omitted from the description.

Synthesis and Application of Pathology Descriptions

• Workflow for Drafting Gross Descriptions:

  1. Systematic Data Collection: Examine the specimen and record data points under each heading of the SALT checklist (Site, Size, Shape, Appearance, Distribution/Extent, Texture).

  2. Descriptive Synthesis: Combine the itemized observations into a concise, fully descriptive paragraph or sentence.

  3. Separation of Objective Description and Diagnostic Interpretation: Keep objective physical characteristics entirely distinct from medical interpretation or diagnostic conclusions.