4. The process of Diagnosis ✅

DIAGNOSIS

Instant recognition of a disease from previous experience

What process is occurring? - 1st question

What tissue is involved?

Past & present medical & dental histories

Medication history (side effects of medicine)

Radiographic, clinical & pathologic correlations

SIRMIN- origin of disease

Structural Processes

Longstanding and unchanging

May have family history

May be congenital

Young patients often

Slow to develop

Immune Processes

Features may overlap with infections

Classic signs of inflammation

Pain or itching ex herpes

Females > males generally

Allergic or autoimmune

Response to steroids

Reactive Process

 Reaction to what?

–Physical, chemical, radiation, trauma?

Should resolve when the causative agent goes away (~10 days)

May mimic neoplasm

Metabolic Processes

Usually a systemic condition

Other medical findings

May be hormonal

May be nutritional

May be genetic

Infectious

Classic signs of inflammation

Often painful

May look similar to tumors

Source of infection?

Radiographic findings

Soft tissue findings

Response to antimicrobials

Neoplastic Processes

Benign neoplasms

Usually encapsulated

Usually slow growing

Localized mass

even if its benign you will biopsy to ensure no malignant cells + it can turn malignant

tori

Malignant Neoplasms

Usually NOT encapsulated

Usually NOT slow growing

More likely to mimic infection

Ill defined mass (so is an infection)

May be painful or cause loss of sensation (so may an infection)

May cause enlargement of lymph nodes (so may an infection)

Types of Oral Tissues: Epithelium

Surface Mucosa: oral cavity has squamous epithelium

Under surface: Salivary, Odontogenic

Types of Oral Tissues: Connective Tissue

Hard - bone or cartilage

Other - fibrous, fatty

Blood vessels or blood cells

Muscle

Nerves

Look for Evidence of Disease

Changes in

• Color

• Form

• Function or sensation

• Feel

Changes in Color: White

white = Less blood visible

• Thick epithelium

• Calloused epithelium

• Scarred fibrous tissue

• Pseudomembrane (rubs off)

Changes in Color: yellow

Fat or xanthoma cells

Sebaceous glands

ex: lipoma (benign)

Changes in Color: Brown/blue/black

Melanin

Foreign sources

Systemic conditions

Physiological

melanoma = most common pigmented lesion

changes in form: When a lesion grows under the epithelium in connective tissue

it creates a smooth-surfaced lesion by stretching the overlying epithelium

Masses that arise under the epithelium are usually smooth

changes in form: When epithelium grows faster than connective tissue

a rough surface results.

corrugated, papillomatous or verrucous

these pictures arise from epithelium because its rough

Flat colored lesions

Local deposits of pigments

Slight local changes in blood vessels

Not significant change in cell number or size

Form

Bilateral lesions, rarely neoplasms – Usually normal anatomic structures

Exceptions i.e. Multifocal canalicular adenoma

Systemic diseases may present multiple lesions

• Metabolic - Addison, Iron deficiency

• Neoplasms - Lymphoma, Metastases

• Infections

• Developmental - Syndromes

Loss of Function - sign of Inflammation

Sialadenitis: saliva flow altered

tendinitis: difficulty moving muscles

Loss of Function - sign of Malignancy

Squamous cell carcinoma of the tongue

May produce change in phonation as tumor invades muscle

change in Function or Sensation

Pain due to a tumor

Most tumors painless

Some intrinsically painful - Osteoblastoma

Invade nerve sheath ---Adenoid cystic carcinoma

• invade nerve = perineural invasion

Destroys adjacent tissues - Pancreatic adenocarcinoma

change in feel: freely movable

A mass that is freely moveable in all directions is usually benign or encapsulated, originating in the underlying connective tissue.

Example: Lipoma

When the mass is fixed in deep connective tissues, you need to figure out what tissue the mass is bound to - That is likely the tissue of origin

change in feel: attached to skin

A mass that moves freely but together with the overlying epithelium probably arises in the epithelium

Example: Nevus (mole

Induration

may indicate:

• Fibrosis

• Infection

• Malignancy

Spreading from epithelium to deeper tissues

Spreading from deeper structures to epithelium

Differential Diagnosis

A list of diseases with features consistent with the observed signs and symptoms

Arranged in order of probability, as determined by epidemiology and frequency of occurrence

you pick MOST likely

Working Diagnosis

Most likely of the diseases in the differentialdiagnosis

Next steps in managing the patient is based on the working diagnosis

BIOPSY

Surgical removal of living tissue for definitive diagnosis

Must be representative of the lesion

Examined microscopically

Is only performed IF INDICATED BY THE WORKING DIAGNOSIS

Biopsies are fairly costly and stressful for a patient - Use them when you need them! But use them wisely

Problems with biopsy before establishing the working diagnosis

Wrong type of biopsy?

Wrong type of fixative?

Risky biopsy?

Inappropriate biopsy?

Unnecessary biopsy?

When to Do a Biopsy

When signs and symptoms of the lesion do not provide enough information to make a definitive diagnosis

If neoplasia is in the differential diagnosis

Any chronic non-healing ulcer of more than two weeks duration

ulcer

yellow appearance with red border

THINGS TO WATCH OUT FOR

If working diagnosis doesn’t call for a biopsy, don’t do it

e.g

• Herpetic gingivostomatitis

• Hematoma following trauma

• Chronic periodontitis

• aphthous ulcers

Risk of trauma, infection, bleeding, and complications

Systemic health of the patient (i.e. bleeding disorder)

Skill of the clinician

Refer to appropriate health care provider - such as OMS

Types of Biopsies: Incisional Biopsy

A representative portion of the lesion is removed

Most of the lesion is left behind

Should try to include normal tissue at edge of lesion

For large lesions or suspected malignant neoplasms

ex: lichen planus (immune related)

Types of Biopsies: Excisional Biopsy

Entire lesion is removed

Also margin of normal tissue

Small lesions

Not expecting malignancy

Other kinds of Biopsy: Punch biopsy

can be incisional or excisional depending on size

Other kinds of Biopsy: Shave biopsy

Esthetic areas such as anterior gingiva

Superficial lesions only, such as lip epithelium

other kinds of Biopsy: needle biopsy

For deep tissues not accessible by direct exploration… e.g. Thyroid gland

Not usually needed for oral lesions

Cytologic Smear Biopsy

Scrape mucosa with spatula

Collect cells on glass slide

Fix cells with cytospray / hairspray containing alcohol

Write patient name on slide

Diagnosis of candidiasis

Pap Smear is a type of cytologic smear

Why not smears to diagnose oral dysplasia?

Cell sample

• Abnormal + normal cells

• Only surface sampled

• Typically 300,000 cells per slide

• “Needle in a haystack”

No architecture is visible

• Cells, but no pattern to them

Improvement in Cell Sampling – Cytobrush Biopsy

Cells from all layers of epithelium if used as directed

• Lab will reject biopsy if sample is not optimal

• Only tested on white lesions

Toluidine Blue

Stain with affinity for perinuclear cisternae of DNA and RNA

Only + areas retain dye after rinsing with acetic acid

Theoretical risks of a vital dye incorporated into cellular DNA

Rate of false positives

• hyperactivity/ Inflammation / ulceration may give false readings

Return visit within 14 days if a test is positive, to repeat the procedure

Misuse in inexperienced hands

Submission of Biopsy

All specimens need to be put in preservative immediately

Make sure you have it before you cut

10% buffered formalin usually

Spray a smear with fixative

Sometimes other special preservatives

Next best is clear ethanol - drinking alcohol like vodka, NOT rubbing alcohol

Fixation for Immune Lesions: Michel’s Solution

Used fresh

Refrigerate for up to 2 weeks

Request in advance

Which lesions?- Vesiculobullous (blister) autoimmune diseases

put ½ lesion in this + ½ in formalin

What’s Next?

Dentist correlates microscopic and clinical findings

Dentist informs patient of her/his diagnosis

Pathologist will not release results to patient

Dentist decides on and arranges further treatment, if any