Artifacts in Histological Preparations

Microwave heating

It’s a kind of low power energy carried by micro-waves

Internal direct heating is our advantage

It’s a physical effect, neither chemical nor magical

Perception Reality

Microwaves cook my samples Microwaves create physical heat like conventionals do, but internally in the tissues. Better homogenity & efficiency.

Rapid processing = poor morphology

Today’s technology makes 12-14 hours an inefficient use of time. Quality is guaranteed priority.

Antigens will be lost forever Diagnostic equivalence is validated by studies showing optimal antigen reactivity.

Molecular studies are not possible

Microwave do not affect DNA, RNA and proteins’ quality at all.

Day processing is useless Day processing = same day diagnosis = patient centric care

1.Samples Preparation

Artifacts

Heat Damage

Fig.1 Breast biopsy

Damage from laser-generated heat or over-heated wax or while drying slides:

• loss of nuclear and cytoplasmic detail

• connective tissue fibers become coagulated

Crush Artifact

Fig.2 Section of lymph node

Damage from crushing by forceps or other surgical instruments:

• darkly staining

• distorted cell nuclei

• some stretching and flattening of tissue

Postmortem Change

Fig.3 Section of liver

Autolysis for delay of fixation:

• poorly defined nuclei

• imprecise cytoplasmic staining

Specimen Marking Dyes

Fig.4 Skin biopsy

Excision margins marked with coloring agents:

• not natural color of the margins

• possible penetration into the tissue

2.FixationArtifacts

Zonal Fixation

Fig.5 Section of liver

Different degrees of fixation at different levels within the specimen:

• insufficient time in fixative

• specimen too large

• reagent with poor penetration rate

Streaming Artifact

Fig.6 Section of liver

Precipitation and displacement of glycogen by an advancing fixation front

Formalin Pigment

Fig.7 Red cells in a section of kidney

Reaction of non-buffered (pH acid) formalin with hemoglobin:

• pigment as a brown to black associated with red blood cells

Mercury Pigment

Fig.8 Section of kidney

Fixation in mercuric chloride-containing fixatives:

• random brown to black granular deposits

3.Tissue-ProcessingArtifacts

Vessel Shrinkage

Fig.9 Section of brain stem

Poor brain fixation:

• perivascular shrinkage

• membrane separation

Poor Processing

Fig.10 Breast specimen

Inadequate fixation, too short processing cycle, inappropriate or exhausted reagents, mechanical fault with the processor, wrong replacement of solvents:

• extensive loss of architectural detail and clarity

• disruption within loose connective tissue

Imcomplete Dehydration

Fig.11 Gastrointestinal biopsy

Incomplete dehydration during processing:

• loss of nuclei details

• cloudy appearance of sections

Under Decalcification

Fig.12 Section of bone

Inadequate decalcification:

• appearance of dark blue areas with hematoxylin in the trabeculae

Over Decalcification

Fig.13 Sections of bone

Excessive decalcification:

• loss of all nuclear detail

• distruction of tissue morphology

4.StainingArtifacts

Residual Wax

Fig.14 Section of skin

Incorrect dewaxing prevents solutions penetration:

• presence of areas totally absent of stain

Incomplete Staining

Fig.15 Section of liver

Inadequately filled staining dish:

• absence of stain in some area of the section

Nuclei Not Crisp

Fig.16 Section of skin

Incomplete fixation or residual water after dehydration:

• “smudgy” or not crisp nuclei

• no distinct chromatin patterns

Thanks