Gross Pathology - Reportable Features of Most Lesions
Location-Spatial arrangement of lesionsColorSize/Weight -Compare paired organs-Absolute vs. relativeShape/Contour-Does lesion have geometric shape?-Flat or raisedConsistency/Texture-Solid, amorphous, fluid, soft, firm...Number (#) or Percent (%) Involved-Distribution of the lesions/extentContentDemarcationOdor
Gross Pathology - Distribution
Assist in estimating severity or significanceOne of the most important observationsRandom-Scattered throughout an organ not associated with architectureSymmetrical-Some degree of organization-Bilateral may imply metabolic-Lesions often highlight an anatomic or physiologic featureFocal-Single defined lesionMultifocal-More than one single discrete lesion - several to many-Multifocal widespreadMultifocal to coalescing-Lesions appear to be fusing-Indicates an active process that is expandingMiliary-Like multifocal but numerous tiny foci too numerous to count-Implicates recent eventSegmental-Well defined portion is abnormal-Pathologic process may be restricted-Vascular bedDiffuse-Everything in area of interest is affected-Implies greater severity
scattered through an organ, not associated with architecture; no pattern
organized, may be bilateral
single defined lesion
more than one discrete lesion; similar to random
lesions become less discrete, start to fuse/merge
tiny multifocal lesions
well defined portion is abnormal
Well demarcated-Abrupt boundary between normal and abnormal-Separated by capsule or necrosisPoorly demarcated-Boundary between normal and abnormal is indistinct-Lesion and adjacent tissue are similar; process is gradually infiltrating
Raised-Implies something is added to the area (fluid, gas, cells, stroma, foreign material)Depressed-Something is removed or lost (necrosis, atrophy)Flat-May be recent or a lesion that doesn't cause expansion or necrosis
Normal determined by cells, stroma, blood supply, pigmentsRed to red/black-Blood or hemoglobin-Hemorrhage = poorly demarcated-Congestion = wider spreadWhite/grey or yellow-Coagulative necrosis -Exudate - white discharge - infectious or inflammatory-Fibrosis - scarring/white-Hyperplasia - increase in size or number of something-Neoplasia-In CNS = malacia - softening/yellow-In liver = lipidosis - fat accumulation/white or yellowGreen-Bile or bile pigments-Coagulation necrosis-Eosinophilic inflammation-Plant material / fungi / Pseudomonas bacteriaGreen - Black-Pseudomelanosis: artificial staining of tissue postmortem by bile and H2S from GITBlack-Melanosis - flat-Melanoma - raised
Size (lesions)Uniform - lesions are all about the same size-Early, progressing at same rateNon-uniform - lesions are of differing size-Events are separated in time or different rates of progressionSize (whole organs)Larger than normal = something added-Bulge when capsule cutSmaller than normal = something removed/lost-Hypoplasia, atrophy, necrosis-AbsentSize (paired organs)-Which one is normal/abnormal?
Texture (cut surface)
Amorphous-Unorganized, no architecture: pus, exudates, necrosisSolid-Has structure, holds shape
Gas: emphysema (air trapped in tissue)Fluid: wet tissue (edema, effusions...)Soft: fluid cell rich, minimal stromaFirm: a lot of stromaHard/gritty: mineral, calcification
Weigh on scale; difficult to establish normalsHeavy = something addedLight = something removed**lungs: + fluid, - air....do they sink or float?
Crepitus = popping air (emphysema, gas producing bacteria)
Foul: putrefactionAmmonia: uremia - end stage kidney disease Apple cider: GI hemorrhage ?No odor: septic or aseptic
Estimate of % of tissue or organ affectedLung and kidney
-Interpretation of the pathological process-Accurate descriptions of what is observed to formulate a presumptive diagnosis-i.e., "kidneys were diffuse, pale, wet, and bulged on cut surface"; "there is a 3 cm white, round mass in the liver...
Submission of Specimens
-Always include signalment and clinical history - diagnosis may be more accurate and won't bias the pathologist-Cite the source tissue---May not change diagnosis but can make a difference in expected biological behavior-Questions of interest-Previous medical history, duration illness, and treatments administered essential for necropsy-Use veterinary pathologists!
The Technician's Role
Career as necropsy technician-Perform the necropsyPlacing tissue in formalin containers-Surgical or necropsy specimens-Accurate labelling-Appropriate size specimen-Appropriate ratio tissue to formalinCollect parasites from GI tract (Chapter 49 of Lab Procedures text)-Decanting method-Sieve method-Preserve in 70% alcohol or 10% formalinSubmit Paperwork-Accurate info including history