Radicular cyst

(1)

Histological differences between papillomatous and verrucous exophytic lesions

Stalk

Flat basal cell layer

(2)

What is keratin plug?

Keratin plug

(3)

Normal Lentigo simplex Junctional activity

Compound nevus Intramucosal nevus Blue nevus Compound: Junctional + Intramucosal

(4)

Junctional activity

Intramucosal nevus

Compound nevus Intraoral

Cutaneous

Limina propria

(5)

Verocay Body: Acelluclar eosinophilic structures Antoni A Tissue: Elongated spindle-shaped cells

with palisaded nuclei

Antoni B Tissue: Loose, scattered spindle cells

Neurilemmoma (Schwannoma)

(6)

Pulp polyp (Open pulpitis,

chronic hyperplastic pulpitis)

(7)

1/3 cases: covered with stratified squamous epithelium

Possible sources of epithelium: (1) derived from stem cells of the pulp tissues; (2) migrated from the adjacent oral

mucosa; (3) 半壞死之keratinocytes進入營養的環境內生長而成

(8)

2/3 cases: without covered stratified squamous

epithelium

(9)

Reparative dentin (tertiary dentin)

Infected dentin

reparative dentin (tertiary dentin)

Primary & secondary dentin are normally formed & perhaps with reversal lines; tertiary dentin is formed due to infection

(10)

Candidiasis (Thrush, candidosis)

(11)

Smear-

gram (+) stain

Long hyphae & occasional yeast cells

(12)

Hyphae : not easily to be observed H&E stain

(13)

Hyphae: more easily to be observed (grow straight downward the epithelium)

PAS (periodic acid-Schiff) stain

Grocott stain: hyphae even more clearly

(14)

Apergillosis

Methenamine silver stain)

Mass of hyphae (fungal ball) Septate branching hyphae with even diameter

(15)

Actinomycosis

Pus discharge

(16)

Actinomycosis

Gram stain

Gram (+) filament:

radially (rosette) arranged

Gram (-) peripheral clubbing

(sulphur granules)

(17)

Tuberculosis

Definition of epithelioid cell

A nonepithelial cell, especially one derived from a macrophage, having characteristics resembling those of an epithelial cell, often found in granulomas associated with

tuberculosis

Langhans giant cell

≠

Langerhans cells

(18)

Fig. 1 Multiple granulomas (arrow) in the lung The granulomas are various in size.

Tuberculosis

(19)

Fig. 2 The large granuloma with central caseous necosis (C) The caseous necrotic debris is surrounded by epithelioid macrophages (E). The outermost area of the granuloma is surrounded by lymphocytes (L).

Tuberculosis

(20)

Fig. 3 Caseous necrosis (C) surrounded by epithelioid

macrophages (arrow). The epithelioid macrophages have abundant eosinophilic cytoplasm & kidney-shaped nuclei

Tuberculosis

(21)

Fig. 4 Epithelioid macrophages (arrow). The macrophages have abundant cytoplasm & kidney-shaped nuclei. They are ovoid in shape

Tuberculosis

(22)

Fig. 5 Langhans giant cell (arrow) has multiple nuclei

These nulcei are arranged in the periphery of cytoplasm

Tuberculosis

(23)

Fig. 6 Small granuloma without caseous necrosis^.

Tuberculosis

(24)

Tuberculosis

Confluent of epithelioid macrophages with indistinct cell boundary

(25)

Tuberculosis

(26)

Accumulation of epithelioid macrophages give rise to LC

Tuberculosis

(27)

Tuberculosis

Accumulation of epithelioid macrophages give rise to LC

(28)

Cholesterol cleft:

found in the cyst wall

release from the membrane of the RBC Hyaline body (Rushton body):

a secretory product from odontogenic epithelium

found in the epithelium

Radicular cyst

(29)

Microscopic criteria:

epithelium is of uniform thickness (7-10 cells thick without rete ridges)

 in parakeratotic type, the epithelium

has a palisaded layer of tall basal cells, is often much folded

in orthokeratotic type, basal cell layer is cuboidal or flattened. There is a conspicuous granular cell layer and keratin may fill the cyst cavity

 corrugated epithelium

Odontogenic keratocyst

(30)

Microscopic criteria:

epithelium is weakly attached to and readily separates from fibrous wall

daughter cyst or epithelial islands are occasionally present in the cyst wall

if inflammation exists, the

characteristics appearance of

epithelium are lost, so that the lining resembles radicular cyst

Odontogenic keratocyst

(31)

Ghost cell (swollen, keratinized, anucleate):

derived from coagulation necrosis of epithelium

aberrant keratinization of epithelial cells

found within the epithelium or large masses extending into and filling the cavity

may also extend into the cystic wall

may mineralized into calcified mass of various size

Gorlin cyst

dentinoid substance may be formed under the induction of the epithelium

(32)

Monostotic:

80-85% of all cases

Fibrous dysplasia

Bone trabeculae assume curvilinear shapes, so like Chinese script writing Polyostotic:

Jeffe type

Jeffe type + cutaneous pigmentation (café au lait spots) + sexual precocity

(female) (McCune Albright syndrome)

Fibrous tissues replace the bone;

bone trabeculae are formed by fibrous

metaplasia but may undergo progressive mauration to a lesion consisting oflamellar bone

(33)

Fibrous dysplasia

What is the difference between fibrous dysplasia and ossifying fibroma?

Microscopically, fibrous dysplasia does not have capsule whereas ossifying

fibroma is encapsulated

Radiographically, fibrous dysplasia is ill- defined while ossifying fibroma is well- defined

Woven bone = Immature bone

(34)

Fibrous dysplasia-X ray

Orange peel;

ill defined

(35)

Ossifying fibroma-X ray

(36)

Ostogenic sarcoma

Most are central type

Rarely, peripheral type (extraskeletal) is also occurred in the oral soft tissue

(primary or metastatic)

(37)

(38)

(39)

(40)

(41)

Mucocele

Is mucus the same as mucin?

Only when special stain such as

mucicarmine or PAS stains is positive, the eosinophic substance is called mucin;

otherwise it is called mucus

(42)

Pleomorphic adenoma

Double layer with myoepithelial cells surround the ductal epithelial cells

(43)

Mucoepidermoid carcinoma

PAS stain Mucicarmine stain

(44)

Mucoepidermoid carcinoma

Clear cell : stain

negatively for mucin, fat and

glycogen

(45)

Mucoepidermoid carcinoma

Squamous cell = epidermoid cells

Intermediate cell : smaller than the

mucous or epidermoid cells; have small darkly staining

nuclei &

scanty pale eosinophilic cytoplasm

(46)

Oncocytoma

Oncocytic cells are senile changes of the acinus cells

(47)

Oncocytoma

Oncycytes have abundant of mitochondria

EM

(48)

Oncocytoma

EM

(49)

Oncocytoma

EM

(50)

Adenocytic carcinoma

(adenoid cystic carcinoma)

Must observe for whether there is nerve invasion

Another salivary malignancy is

polymorphous low grade adenocarcinoma (PLGA) may also have nerve invasion

Solid type usually has central necrosis

Rarely, oncocytoma may also have nerve invasion. Inconsistent with its benign

behaviour

(51)

Neural invasion

Adenocytic carcinoma

(adenoid cystic carcinoma)

(52)

Polymorphous low grade adenocarcinoma

(53)

Polymorphous low grade adenocarcinoma

(54)

Polymorphous low grade adenocarcinoma

Indian fire arrangement

(55)