SUBMITTED TO: Dr.D.V.JOSHI (Head of dept. of pathology)

SUBMITTED BY: BHARAT CHAUDHARY ROLL NO: 02 REG NO:02-00400-2010

An Assignment

onSeborrhoea

under tracking programme

Seborrhea or seborrheic dermatitis is a skin disorder in which the sebaceous glands of the skin produce an excessive amount of sebum.

Seborrhea typically affects the back, face and flanks causing scaly, flaky, itchy, red skin.

What is seborrhea?

Seborrhea disease

Most dogs with seborrheic dermatitis have a combination of dry and oily seborrhea.

There are two types of seborrhea, called seborrhea sicca meaning dry seborrhea, and seborrhea oleosa (oily seborrhea). 

In dogs: seborrhea usually affects skin areas that are

rich in sebaceous glands, especially the skin along the back.

What are the clinical signs of seborrhea?

Some skin areas may be red and inflamed, with either a dry or an oily feel to the lesions.

The dermatitis may be worse in areas with skin folds such as the feet, neck, lips, armpits, thighs, and underside.

The affected areas of skin often flake off in whitish scales (dandruff) that can be seen on the dog's bedding and other places where the dog lies.

" Many dogs will have an odor associated with seborrhea.“

Many dogs will have an odor associated with seborrhea. This odor is usually worsened if the seborrhea is complicated by a secondary bacterial or yeast skin infection.

In some cases, the exact cause of seborrhea cannot be determined (calledidiopathic seborrhea). Seborrhea is often related to an underlying medical problem, such as:

Hormonal imbalances - thyroid disease, Cushing's disease, etc.

Allergies

What causes seborrhea?

Parasites (internal and external) - fleas, ticks, mange mites

Fungal infections - especially yeast skin infections

Dietary abnormalities - poor diets containing low levels of omega-3 fatty acids

Environmental factors (temperature, humidity changes)

Obesity Musculoskeletal disease or pain - the dog is

unable to groom itself properly

Tests that can aid your veterinarian in diagnosing your dog's seborrhea include:

Complete blood cell count (CBC), serum chemistries and electrolytes - looking for subclinical or hidden underlying conditions or imbalances

Skin cytology and/or skin scrapings

How is seborrhea diagnosed?

Skin culture - for bacterial and fungal infections, including ringworm

Skin biopsy Hormone tests - including thyroid disease

and Cushing's disease testing

Treatment is aimed at the underlying cause.  If no underlying cause can be found, then a

diagnosis of primary or idiopathic seborrhea is made.

Unfortunately, there is no specific treatment for primary seborrhea. In general, treatments that help manage seborrhea include:

How is seborrhea treated?

Omega-3 fatty acid supplements Antiseborrheic shampoos Moisturizers Retinoids Oral cyclosporine Antibiotics - to treat secondary bacterial

infections

The prognosis for seborrhea is based on your dog's specific condition and severity. 

The prognosis is better if an underlying cause has been identified and treated. 

What is the prognosis for seborrhea?

(Synonym: granulomatous sebaceous adenitis)

SEBACEOUS ADENITIS

SEBACEOUS ADENITIS IN DOG

Sebaceous adenitis is an uncommon canine and rare feline skin disease of uncertain etiology

Hypotheses for the pathogenesis of sebaceous adenitis include heritable and developmental (‘predetermined’)

Clinical features

inflammatory destruction of the sebaceous glands, cell- mediated immunologic destruction, a cornification abnormality leading to sebaceous duct and sebaceous gland inflammation and atrophy,

Sebaceous adenitis in German Shepherd Dogs may begin on the tail and progress up the trunk.

Feline sebaceous adenitis is characterized by multifocal, annular areas of alopecia with scaling, crusting, and follicular casting

Clinical differential diagnoses for canine sebaceous adenitis characterized by generalized scaling include primary seborrhea and seborrheic dermatitis, ichthyosis, and vitamin A-responsive dermatosis.

Demodicosis and generalized dermatophytosis also may mimic sebaceous adenitis.

Differential diagnosis:

Multiple specimens are recommended so that adequate numbers of adnexal units may be observed.

Chronic, extensively alopecic lesions com- monly show an absence of sebaceous glands without significant inflammation; multiple specimens are then essential to confirm that the absence of sebaceous glands is widespread, and therefore diagnostic of sebaceous adenitis.

Biopsy site selection

Most other cases of sebaceous adenitis exhibit mild to moderate acanthosis and generally moderate to severe hyperkeratosis with follicular plugging.

Histopathology

Clinical features Seborrhea is a confusing, nonspecific name

that has been used to describe the clinical signs of excessive scaling, crusting, and greasiness.

A relationship between the term ‘seborrhea’ and sebaceous gland function has notbeen shown, despite ‘seborrhea’ meaning the excessive flow of sebum.

PRIMARY SEBORRHEA AND SEBORRHEIC DERMATITIS

SEBORRHEIC DERMATITIS

The etiopathologic relationship between vitamin A- responsive dermatosis and primary seborrhea is not known.

The terms ‘seborrhea sicca’, ‘seborrhea oleosa’, and ‘seborrheic dermatitis’ have been used to describe dry and waxy, oily, and focal more inflamed lesions, respectively.

Seborrheic dermatitis is characterized by erythematous, well demarcated to coalescing, somewhat circular plaques.

Alopecia, lichenification, and hyperpigmentation may be evident in older lesions.

Lesions are located primarily on the thorax, especially ventrally.

Lesions

Difficulty in the histopathologic evaluation of primary seborrhea arises from the presence of secondary inflammation, or seborrheic dermatitis.

Seborrheic dermatitis can mimic chronic dermatitis of varying etiology, particularly chronic allergic dermatitis or chronic superficial pyoderma.

Histopathology

Hyperkeratosis is the principal feature of uninflamed primary seborrhea.

Keratin is somewhat amorphous and loosely layered; the typical basketweave appearance of normal keratin is absent.

Most cases of primary seborrhea also have concurrent lesions of seborrheic dermatitis.

The diagnosis of seborrheic dermatitis should not be difficult if concurrent lesions of primary seborrhea are found.

diagnosis

Synonym: canine ear margin dermatosis

Clinical features:

Canine ear margin seborrhea is a relatively common presumed abnormality in cornification.

CANINE EAR MARGIN SEBORRHEA

Adherent keratinous deposits are present on both the lateral and medial margins of the pinna.

Canine sarcoptic acariasis is very pruritic, in contrast to ear margin seborrhea.

CANINE EAR MARGIN SEBORRHEA

Ear margin seborrhea is characterized by severe hyperkeratosis, predominantly manifested by follicular keratosis.

Keratin distends follicular ostia and may give the epidermal surface a pronounced pseudopapillomatous appearance.

Histopathology

Clinical features: Cysts that involve sebaceous structures are

rare in dogs and extremely rare in cats. Sebaceous duct cysts present as solitary

firm dermal nodules that are usually less than 0.5cm in size.

SEBACEOUS DUCT CYST

SEBACEOUS DUCT CYST

Sebaceous duct cysts are lined by a thin layer of stratified squamous epithelium that has a sparse granular cell layer and a corrugated or undulating inner surface.

A thin collagenous capsule usually

surrounds the epithelium.

Histopathology

Most of the cyst contents are lost during tissue processing, but some delicate, lamellar keratin generally adheres to the cyst lining.

Sebaceous duct cysts may need to be differentiated from follicular cysts, particularly the isthmus type

diagnosis

Synonym: senile sebaceous hyperplasia

Clinical features Nodular sebaceous hyperplasia is a

common, focal or multicentric noneoplastic lesion of dogs.

NODULAR SEBACEOUS HYPERPLASIA

NODULAR SEBACEOUS HYPERPLASIA

Nodular sebaceous hyperplasia is characterized by multiple, enlarged, but otherwise normal sebaceous lobules clustered around one or more dilated sebaceous ducts and hair follicles.

Histopathology

The architectural relationships of the folliculo sebaceous units are generally well-maintained.

Affected folliculo sebaceous units may be grouped horizontally, forming a plaque.

Nodular sebaceous hyperplasia should be differentiated from sebaceous adenoma and in some cases from sebaceous nevus.

Nodular hyperplasia retains the normal ori entation of sebaceous glands around ducts or follicular infundibula in contrast to simple sebaceous adenoma.

diagnosis

Clinical features Sebaceous hamartoma is an uncommon

variant of fibroadnexal hamartoma and is a malformation of presumed congenital origin.

Lesions present as alopecic solitary nodules less than 1cm in diameter, most often on extremities or trunk.

SEBACEOUS HAMARTOMA

SEBACEOUS HAMARTOMA

Sebaceous hamartoma is a circumscribed dermal nodule composed predominantly of large sebaceous lobules with a random distribution.

Maturation patterns within the lobules are

normal.

Histopathology

The sebaceous lobules may be contiguous with and interconnected by tortuous sebaceous ducts and small but malformed hair follicles.

Differentiation between sebaceous hamartoma and fibroadnexal hamartoma is based on an obvious predominance of sebaceous lobules in the former.

diagnosis

Synonyms: nevus sebaceus, organoid nevus

Clinical features:

Sebaceous nevi are seen uncommonly in dogs and rarely in cats.

They generally appear as alopecic, scaly or greasy, circular or linear plaques less than 2cm in diameter.

SEBACEOUS NEVUS

SEBACEOUS NEVUS

Sebaceous nevus is a plaque-like, fungiform or polypoid lesion covered by hyperplastic, hyperkeratotic epidermis that has a papillated configuration.

Hypergranulosis is also present and may be marked.

Histopathology

Sebaceous nevus can usually be distinguished from nodular sebaceous hyperplasia by its involvement of larger numbers of folliculosebaceous units and the smaller size of the sebaceous lobules.

diagnosis

Clinical features Sebaceous carcinomas are rare malignant

neoplasms in cats and dogs.

Histologically identical lesions of the specialized sebaceous glands of the eyelids are designated meibomian gland carcinomas.

SEBACEOUS CARCINOMA

Sebaceous carcinomas are usually solitary, firm nodules up to 7.5cm in diameter.

The majority of cases in both dogs and cats occur on the head.

The average age of affected animals ranges from 9 to 12 years

Sebocytic sebaceous carcinoma Sebocytic sebaceous carcinomas are

irregular but circumscribed, multilobular dermal neoplasms composed of islands of epithelial cells that are usually larger than basaoid reserve cells.

Histopathology

Neoplastic cells have eosinophilic cytoplasm with variable vacuolation.

Sebocytic sebaceous carcinomas have small to moderate numbers of cells with finely dispersed lipid droplets resembling normal mature sebocytes.

Distinction between sebaceous epithelioma and epitheliomatous sebaceous carcinoma is problematic and currently controversial.

These two entities are probably closely adjacent in the continuum of sebaceous neoplasia.

Differential diagnoses

Solid basal cell carcinoma may need to be differentiated from epitheliomatous sebaceous carcinoma.

Oil red O or other lipid stain may be required to differentiate a poorly-differentiated, small cell- predominant sebaceous carcinoma from basal cell carcinoma.