◊ 2-Cyst ◊

II-Cyst

Definition: -

It is a congenital or acquired circumscribed non inflammatory hollow swelling or tumor like structure with secretory lining membrane and it contains fluid, semi-fluid, or solid structures like hair or teeth, or they are movable "bags" of liquid or semisolid material that are surrounded by a membrane wrapping. Cysts can sometimes remain at their same size during months or even years. Cysts can be classified into congenital and acquired; and into epithelial, retention, exudative, parasitic, or degenerative.

Classification: -

I-ACCORDING TO HEREDITY

1-Congenital

It is a cyst that presented at birth and it is of embryonic origin formed as a result of failure of embryonic cavity to obliterate or misplacement of certain embryonic tissue.

A-Dermoid cyst

Commonly, it is a subcutaneous cyst that is rarely observed in internal organs (ovary, testicle, or brain). An example of this type is the dermoid that frequently observed in the cornea or conjunctiva of farm animals and sometimes it contain hairs.

i-Simple form: -

It is lined with epithelium and contains mucoid fluid

ii-Compound form: -

It is a Teratoma like cyst that affects calves mainly

Location: -

The neck, Entrance of larynx, Posterior part of lower maxilla

Characteristic : -

Wall is similar to skin (has hair follicle and sebaceous gland)

iii-Follicular cyst: -

Location: -

Bony alveoli, especially the first molar teeth

Characteristics: -

It usually affects foal and increases in size at age of one year

B-Dentigerous cyst

Location: -

At the temporal bone as a sinus opening anterior to ear base

Characteristics: -

It usually affects foal and contain tooth. Thick exudates comes out from the opening of the sinus and when it is probed, the probe will strike the tooth

2-Acquired

It is cysts that are acquired along the life of the animal as a result of certain pathological processes

II-ACCORDING TO CAUSE AND ORIGIN

1-Epithelial cyst

It is a type of cysts that has embryonic origin

A-Dermoid cyst

As mentioned before

B-Tongue base, pharyngeal, or epiglottis cyst

Location: -

Tongue base, entrance of pharynx or larynx, or epiglottis

Characteristics: -

It usually affects calves and foals, and has mucoid contents. It is either pedunculated or not, large round cyst that may interfere with mastication or cause dyspnea and asphyxia

C-Umbilical cyst

Location: -

Umbilical region

Characteristics: -

It usually affects calves and foals and contains mucoid contents with size varies from hen's egg to hand fist size

D-Traumatic epithelial cyst

Contents: -

Grey yellowish mucoid fluid

Characteristics: -

Caused by trauma or fire shooting with sequestration of piece of skin or foreign body at wound base with superficial healing of the wound

2-Retention cyst

It is an acquired cyst formed as a result of obstruction of secretory duct of glands

A-Atheroma

It usually affects horse

Contents: -

Sebaceous

Characteristics: -

It affects sebaceous gland of false nostril leading to stenosis of nasal passage and respiratory noise

B-Mucous membrane cyst

Contents: -

Clear viscid mucoid fluid

Characteristics: -

It is spherical or oval shape cyst formed due to obstruction of mucoid gland

Location: -

1-Inner aspect of the lower lip or sublingual mucous membrane in cattle and horse

2-Rectal mucous membrane of the horse

3-Vaginal mucous membrane of the cow (bartholin gland

C-Salivary cyst (neck cyst, brachial cyst, ranula, or honey cyst)

Contents: -

Honey like thick yellowish saliva (so it is called honey cyst)

Characteristics: -

It usually affects dog or other animals and formed as a result of obstruction of duct of sublingual or mandibular salivary gland. It is round or oval swelling with thin wall formed beside fraenum linguae or tongue (so it is called mouth cavity cyst or ranula), or under larynx or upper part of neck (so it is called neck cyst)

3-Exudation cyst

It is formed as a result of accumulation of exudates in pre-existing cavity as in case of accumulation of fluid in tunica vaginalis after castration or ovarian cyst

4-Parasitic cyst (pseudo-cyst)

It is formed as a result of irritation of tissue by growing parasite with formation of pseudo-cyst surrounded by fibrous tissue

Examples: -

Coenurus cerebralis	Brain of sheep and cattle
Echinococcus cyst (Hydatid)	Kidney, liver, lung, spleen, and bone
Taenia cyst	Masseter muscle and heart in cattle and pigs

5-Degenerative cyst

It associates tumors like cysto-carcinoma, cysto-sarcoma, or cysto-fibroma

Symptoms: -

1-Localized swelling containing fluid (fluctuating), semi-fluid, or solid structures like teeth or hair (dentigerous or dermoid cyst respectively)

2-Slow growth rate and absence of inflammatory signs

3-Well defined periphery with absence of pathological lesion in skin covering the cyst

4-Symptoms are confirmed by exploratory puncturing

5-Radiography diagnoses and confirms bone cyst

Diagnosis: -

1-History       2-Clinical signs      3-Exploratory puncturing        4-Differential diagnosis        5-Radiography

Treatment: -

1-Aspiration of contents by needle or trocar and cannula with injection of irritants like Tr. Iodine or 5% Carbolic acid to destroy secretory lining and to stimulate granulation tissue for obliteration of the cavity or

2-Surgical incision at lowest point and swap with Tr. Iodine to stimulate granulation tissue formation and obliteration or

3-Seton may be used to stimulate granulation tissue formation and obliteration

4-Surgical excision

5-Pedunculated cysts of the base of tongue, vagina, or abdominal cavity can be removed by ecraseur to avoid bleeding or

6-Ovariectomy or castration for removal of ovarian or testicular cyst o

7-Hydrocele can be treated by evacuation of fluid that is followed by castration

8-Dentigerous cyst can be treated by surgical excision, curetting, cauterization of the sinus, then closure of the wound with establishment of an opening at the lowest point for drainage