L7 - Parasitic - Neoplastic Dz Of Skin PDF

Integumentary system: Lecture 6 Contents  6.1 Parasitic diseases of skin - Sarcoptic mange - Notoedric mange - Demodectic mange - Ticks, lice, fleas  6.2 Neoplastic diseases of skin  6.1 Parasitic diseases Sarcoptic mange - lesions is...

Integumentary system: Lecture 6 Contents  6.1 Parasitic diseases of skin - Sarcoptic mange - Notoedric mange - Demodectic mange - Ticks, lice, fleas  6.2 Neoplastic diseases of skin  6.1 Parasitic diseases Sarcoptic mange - lesions is due to:  Direct damage by the parasite  Irritant effects of its secretions & excreta develop allergic reaction  Gross: erythematous macules or papules, local scale crust (burrowing mites)  In poorly nourished animals: alopecia, marked lichenification, accumulation of scale crust & fissuring & self trauma  Histo: vary with the balance between the allergic reactions and parasite infestations  Parasitic diseases Sarcoptic mange  In immunosuppressed animals, large numbers of adult mites lie in burrows lined by parakeratotic s. corneum, thick scale crust composed of ortho- and parakeratotic hyperkeratosis, neutrophils debris & many sarcoptes ova  Histo: Epidermal; marked hyperplasia. Dermal; variable vasodilation, endothelial swelling, oedema, perivascular mononuclear-cell infiltration, neutrophilic exocytosis, fibrosis.  In acute allergic reaction: marked vasodilation, dermal oedema, perivascular lymphocytic eosinophilic infiltration, epidermal spongiosis & hyperplasia & perivascular infiltrate predominantly mononuclear cells.  Parasitic diseases  Canine scabies. a, An adult male contacts an adult female Sarcoptes scabiei on the surface of the normal epidermis. b, After mating, the gravid female burrows into the epidermis and tunnels at a rate of about 2 mm per day, leaving behind her ova and fecal pellets. As the eggs hatch, the larvae bore to the surface and form epidermal molting pockets. After molting they emerge as nymphs. The mites activity causes the skin to react with acanthosis, hyperkeratosis, vascular dilatation and cellular infiltration of the upper dermis, c, intense pruritus causes self-inflicted excoriations. The mite's burrow is opened by the trauma of scratching, and the female mite is exposed. Loss of mites from this process may be the reason that skin scrapings of abraded tissue tail to reveal mites. Eggs and fecal debris which remain in the burrow continue to cause pruritus. Oozing exudates coagulate to form crusts on the surface of the lesions  Parasitic diseases  Alopecia & excoriations  Notoedric mange: marked crusting and excoriation on face of a cat Parasitic diseases : sarcoptic mange  Parasitic diseases  Mite tunneling within cellular crust  Pruritic papules on human arm, a typical skin reaction to animal mites  Parasitic diseases : Demodectic mange  Demodex mites are normal inhabitants of the hair follicles or sebaceous glands in all domestic animals 1. Localised form  Gross: single or multiple, well-circumscribed, erythematous, scaly & alopecic patches.  Histo: predominantly lymphocytic plasmacytic perifolliculitis, marked follicular hyperkeratosis associated with the presence of demodectic mites in the upper third of the follicle. Neutrophils & eosinophils are present in small number  Parasitic diseases  Localized Demodecosis: focal areas of alopecia, erythema and/or hyperpigmentation and comedones  Parasitic diseases : Demodectic mange 2. Generalised or pustular form  Combine effects of follicular keratosis, mite proliferation & folliculitis lead to follicular rupture and release of mites, bacteria, keratin, sebum, and other irritant product into dermis which induces suppurative dermatitis, often with abscess.  Hair follicles (all levels) & sebaceous gland (opening into the pilar canal) occupied / occluded with large no of mites  Gross: patch to diffuse alopecia, erythema, scaling & crusting. 20 bacterial - pyoderma lesions  Histo: Epidermal hyperplasia, ortho- and parakeratotic hyperkeratosis & variable spongiosis, neutrophilic exocytosis, ulceration & inflammatory crusting, granulomatous reaction, few multinucleated giant cells may present, 20 bacterial infections: induces neutrophilic folliculitis, marked dermal fibrosis (chronic lesion)  Parasitic diseases  Generalized demodecosis with secondary pyoderma, note widespread alopecia with scaling/crusting  Parasitic diseases  Demodicosis a, Normal multiple hair follicle with sebaceous gland. b, Localized demodicosis. One hair follicle is shown with a small colony of Demodex canis. A few eggs are seen, and one accessory hair is degenerating and partly broken. A very mild perifollicular infiltrate develops as the follicle dilates. c, Pustule formation in generalized pyogenic demodicosis. The hairs are gone, and a corned, consisting of keratin, sebum, debris and dead mites, plugs the follicular orifice. The ballooning hair follicle accommodates the expanding mite colony, which is packed with numerous adult mites, immature forms and eggs. The clusters of black dots represent staphylococci that have invaded the hair follicle. d, The ballooned hair follicle ruptures and transforms into a pustule, and later an intradermal abscess. The sebaceous gland disintegrates. At this stage there is exudation through the follicular orifice. Some abscesses break through the epidermis separately. The epidermis is acanthotic, hyperkeratotic and crusted. Thousands of similar lesions produce the clinical appearance of generalized pustular demodicosis Parasitic diseases Demodex mites from scrapings Perifolliculitis with demodex mites in follicular lumina  Parasitic diseases Ticks  Vectors for many viral, bacterial & protozoal diseases of domestic animals  Can also cause local skin damage, anemia or paralysis Parasitic diseases  Lice (Pediculosis): many lice with numerous eggs (nits) attached to hairs  Parasitic diseases Fleas  Most important cause of skin disease in small animals (C. felis & C. canis)  Cause pruritus/irritation skin, anemia, infectious disease vectors, HS reactions  Clinically: asymptomatic carriers, flea-bite dermatitis and/or flea allergy dermatitis  Flea dirt (ie flea feces composed of dried digested blood), may be more readily found than the fleas themselves Parasitic diseases Flies  Localized skin damage / pruritus, (fly bite dermatitis)  Hypersensitivity (eg Culicoides hypersensitivity)  Direct toxicity (eg black fly toxin)  Vectors for infectious agents  Myiasis Integumentary system: Lecture 6 Contents  6.1 Parasitic diseases of skin - Sarcoptic mange - Notoedric mange - Demodectic mange - Ticks, lice, fleas  6.2 Neoplastic diseases of skin  6.2 Neoplastic skin diseases  Most common site of neoplasia in most domestic spp  Influenced by genetics, hormones, etc  Ectodermal neoplasms: tumors of the epidermis and adnexa origin  Usually benign.  Eg: papilloma, squamous cell tumor, basal cell tumor, sebaceous gland tumor  Mesodermal: tumors of mesenchymal or round cell origin  Dermis: fibrous tissue, muscle, fat, blood vessels & leukocyte- related cells of dermis: histocytes, mast cells, lymphocytes  Histologically malignant (commonly) and regularly exhibit locally infiltrative growth and occasionally will metastasize  Eg: spindle-cell tumor; fibroma/sarcoma, lipoma/sarcoma  Melanomas: tumors of melanocytic origin  Eg: benign dermal melanomas, malignant melanomas  Neoplastic skin diseases  Neoplastic skin diseases : Papilloma Papilloma  Skin epithelium origin  Variety of forms, from flat, smooth to pedunculated or villous  Eg: Wart Neoplastic skin diseases : Papilloma Histo: Proliferating stratified squamous epithelium in the form of multiple fingers like projections Covered with squamous epithelium which shows hyperkeratosis and acanthosis. Most of the papillary projections are long and finger-like but can be small round and blunt projections.  Neoplastic skin diseases : Adenoma Adenoma Occurs in glands Eg: mammary gland tumour, sebaceous gland adenoma  Neoplastic skin diseases : Carcinoma Eg: Squamous Cell Carcinoma (SCC)  Common neoplasm Gross lesions  Often head (eye/ ear/nose); esp unpigmented areas  Firm, poorly demarcated mass, ulcer, or proliferative  Locally invasive with tissue destruction & slow to metastasis  Neoplastic skin diseases :SCC  Typically metastasize quite late and can become very large if left untreated  Neoplastic skin diseases : SCC go  Characterized by down growth of proliferating cords and nest of neoplastic squamous epithelium; some of which have keratinized central areas (keratin pearls)  Neoplastic skin diseases : Sarcoma Soft-tissue Sarcomas  Cutaneous spindle cell tumor/sarcoma  Common in dogs; less in cats, sporadic horses, rare in others  Eg: Lymphosarcoma Gross  Firm to gelatinous, gray- white nodular masses  Single or multinodular, any site (esp limbs) Neoplastic skin disease : Lipoma  Neoplastic skin diseases : Mast cell tumor  Most frequent potentially malignant skin tumour of the dog Gross  Single or multiple, oedematous nodular masses  Often hairless and ulcerated in late stages  Neoplastic skin diseases : Mast cell tumor  Proliferation of neoplastic mast cells with infiltration of many eosinophils (due to degranulation of neoplastic mast cells which contain inflammatory mediators including chemotactic factors for eosinophils)  Neoplastic skin diseases : Mast cell tumor  Special staining (toluidine blue) used to confirm mast cells tumour  Metachromatic staining of mast cell cytoplasmic granules Neoplastic skin diseases : Histiocytoma  Canine histiocytomas (“button tumor”)  A common, benign, spontaneously regressing tumor, typically seen in young dogs Neoplastic skin diseases : Histiocytoma Round to oval nucleus and cytoplasm has lack of vacuoles and granules  Neoplastic skin disease : Lymphoma Canine lymphoma (epitheliotropic)  Early plaque-like tumor that progressively enlarged over time with lymph node involvement in the late stages VPM 3417: VETERINARY PATHOLOGY III Neoplastic skin disease : Canine lymphoma  Neoplastic skin diseases : Melanoma Melanoma (Melanocytoma)  Common in dogs, gray horses and some swine  Gross: Dark brown-black macules, papules, nodules tumors  Biologic Behaviour (eg in dogs)  Eyelid or skin, if < 2 cm mostly benign  Skin, if > 2 cm or digits/nailbed mostly malignant  Oral cavity invariably malignant Melanocytoma / Malignant Melanoma: melanoma pigmented nodule at the nasal from the digit planum of a dog of a dog  Neoplastic skin diseases : Melanoma  In most case the tumors are melanocytomas (ie benign melanocytic tumors)  Can progress to malignant melanomas in some cases Neoplastic skin diseases : Melanoma  Large black mass (ie  Histologically: melanoma) on shoulder proliferation of neoplastic region of pig melanocytes Circulatory disturbances VPM 3417: VETERINARY PATHOLOGY III I.. 2.. 3 tipen Pannicality 4.