Integumentary System.pdf

Includes: Skin, accessory structures (hair, nails, glands), blood vessels, muscles, nerves The skin is considered the largest organ of the body Thinnest on the eyelids Thickest on the heels (average thickness is 1-2 mm) Two major layers: Outer, thinner layer or epidermis, consists...

Includes: Skin, accessory structures (hair, nails, glands), blood vessels, muscles, nerves The skin is considered the largest organ of the body Thinnest on the eyelids Thickest on the heels (average thickness is 1-2 mm) Two major layers: Outer, thinner layer or epidermis, consists of epithelial tissue Inner, thicker layer or dermis, beneath the dermis is a subcutaneous layer Epidermis Composed of 4 types of cells: ○ Keratinocytes (90% of the cells) that produce keratin Gives thickness/consistency ○ Melanocytes- which produce melanin Produces different colors in skin, eyes Has digitations to expand ○ Langerhans cells: involved in immune responses Activated during inflammatory responses in the skin ○ Merkel cells: perception along with the adjacent tactile discs because it is connected to the nerve How we perceive touch Four major layers (thin skin) or 5 major layers (thick skin) 1. Stratum basalis: continuous cell division 2. Stratum spinosum: 8-10 layers of keratinocytes 3. Stratum granulosum, which includes keratohyalin and lamellar granules 4. A. Stratum lucidum is present only in thick skin (the skin of the fingertips, palms, and soles) B. Stratum corneum: many sublayers of flat, dead keratinocytes called corneocytes or squames replaced by cells from deeper strata Dermis Composed of connective tissue containing collagen and elastic fibers, attachment of epidermis Two layers: Papillary region (outer layer) ○ Areolar connective tissue containing thin collagen and elastic fibers ○ Dermal papillae (including capillary loops), corpuscles of touch and free nerve endings Reticular region (deep layer) ○ Dense irregular connective tissue containing collagen and elastic fibers ○ Adipose cells ○ Hair follicles ○ Nerves ○ Blood vessels ○ Sebaceous (oil) glands ○ Sudoriferous (sweat) glands Lines of cleavage- “tension lines” in the skin indicate the predominant direction of underlying collagen fibers Important for surgical procedures Follow lines of cleavage to avoid scarring  Epidermal ridges reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints) Their function is to increase the firmness of grip by increasing friction Structural basis of skin color Variations in skin color arise from amounts of 3 pigments: melanin, carotene, and hemoglobin ○ Melanin: pigment produced by melanocytes which absorbs UV radiation The number of melanocytes are about the same in all people (differences in skin color is due to the amount of pigment produced) ○ Carotene: vegans who abuse the intake of carrots, pumpkins, their skin may present more yellow or conjunctiva looks orange ○ Hemoglobin: if a patient is anemic, they do present more white in skin color Subcutaneous layer (hypodermis) (not part of the skin) Functions ○ Attaches the skin to the underlying tissues and organs ○ Contains lamellated (Pacinian) corpuscles which detect external pressure applied to the skin Accessory structures of the skin (hair, skin glands, and nails) Hairs (pili) ○ Functions: protection, reduction of heat loss, sensing light tough ○ Composition (dead, keratinized epidermal cells) Anatomy of the hair: Shaft- mostly projects about the surface of the skin Root- which penetrates into the dermis Hair follicle Epithelial root sheath = epidermis Dermal root sheath = dermis ○ Different types of hairs include: Lanugo, Vellus hairs, and terminal hairs ○ Hair color is determined by the amount and type of melanin ○ Sebaceous (oil) glands are connected to hair follicles  Skin glands ○ Sebaceous glands- attached to follicle Secrete an oily substance called sebum which prevents dehydration of hair and skin, and inhibits the growth of certain bacteria (protection essentially) ○ Sudoriferous (sweat glands)- increases temp. Eccrine: drains directly to skin- attempts to decrease temp. Or merocrine sweat glands helps to cool the body by evaporating and also eliminates small amount of wastes Apocrine: stimulated by stress, excitement (sympathetic action) Located mainly in the skin of the axilla, groin, areolae, and bearded facial regions of adult males Their excretory ducts open into hair follicles- this sweat is secreted during emotional stress and sexual excitement Both can be activated and the same time ○ Ceruminous glands Modified sweat glands located in the ear canal Together with nearby sebaceous glands, produce a waxy secretion called cerumen (earwax) Works as a sticky barrier Nails ○ Composed of hard, keratinized epidermal cells located over the dorsal surfaces of the ends of fingers and toes ○ Structures: Free edge Transparent nail body (plate) with a whitish lunula at its base Nail root embedded in a fold of skin, promotes nail growth Stress, inflammation, trauma can increase nail growth Any trauma to nail root can lead to different growth of the nail Types of skin Thin hairy skin: covers all body regions except the palms, palmar surfaces of digits, and soles Thick hairless skin: covers the palms, palmar surfaces of digits, and soles Functions of the skin Regulation of body temperature Blood reservoir Protection Cutaneous sensations Excretion and absorption Synthesis of vitamin D Development of the Integumentary System The epidermis develops form the ectoderm Nails, hair, and skin glands are epidermal derivatives- the epidermis of a fetus is protected by a fatty substance called vernix caseosa The dermis develops from the mesoderm Aging and the integumentary system effects: Wrinkling Decrease of skin’s immune responsiveness Dehydration and cracking of the skin Decreased sweat production Decreased numbers of functional melanocytes resulting in gray hair and atypical skin pigmentation Loss of subcutaneous fat General decrease in skin thickness Increased susceptibility to pathological conditions Growth of hair and nails decreases Nails may also become more brittle with age Macule: Circumscribed area characterized by flatness and distinguished by its color Papule: Elevated solid area (5 mm, it is know as nodule Plaques: elevated flat-topped area (> 5mm) Vesicle: fluid-filled raised area (+/- 5 mm) Pustule: pus-filled area in the epidermis An abscess in pus in the dermis and is retained there Bullae: fluid-filled area (> 5 mm) Scale Dry horny, plate-like excrescence result of imperfect cornification-(break of keratin in epidermis Lichenification Thickened and rough skin (repeated rubbing or scratching) Secondary to constant trauma Bigger layer of keratinocytes are triggered by constant trauma Pointy bleeding in area from heavy, constant scratching Excoriation Traumatic lesion (deep scratch) Removing epidermis Psych patients can have these lesions Microscopic Terms Papillomatosis ○ Hyperplasia of papillary dermis Lentiginous ○ Linear pattern of melanocyte proliferation of the melanocytes within the epidermal basal layer Hyperkeratosis ○ Hyperplasia of stratum corneum (increase of scaly material- psoriasis) Achantosis ○ Epidermal hyperplasia Dyskeratosis ○ Abnormal keratinization, has more keratinocytes Parakeratosis ○ Retention of nuclei in the stratum corneum ○ Cells do not die correctly (nuclei should disappear) and nuclei is still present Spongiosis ○ Intracellular edema Achantolysis ○ Loss of cellular connections ○ Detachment of different layers in epidermis Acute Inflammatory Dermatoses Acute lesions of short duration (less than 3 weeks) Characterized by mononuclear inflammation and edema due to epidermal, vascular, or subcutaneous injury Acute Eczematous Dermatitis ○ Classification Contact dermatitis Atopic dermatits Atopic eczema (atopic dermatitis) is one of the most common forms of eczema, a condition that causes the skin to become itchy, dry and cracked ○ Drug-related dermatitis Photoeczematous eruption Primary irritant dermatitis Urticaria ○ Most cases results from allergic reaction mediated by IgE (food, pollen, drugs, insects venom, etc.) culiminating in pruritic edematous plaques (wheals) ○ Most commonly affects subjects between 20-40 y/o ○ Chronic Inflammatory Dermatoses Lesions of longer duration (more than 3 weeks) Psoriasis ○ Stratum corneum is affected and common to present in plaques ○ Common dermatosis which affects 2% of population. Pathogenesis: Unknown. ○ Sometimes associated with arthritis, myopathy, enteropathy, and AIDS ○ Commonly affects the elbows, knees, scalp, etc. typical lesion ○ Well demarcated pink colored plaque covered by silver-white scales ○ Auspitz’s Sign- pinpoint bleeding in areas where the plaque of a scaling rash has been removed as well as when scratched, the area increases ○ ○ Microscopically: epidermal hyperplasia, parakeratosis. Microabscesses within superficial layers Chronic Dermatoses ○ Lichen planus Self-limiting disorder which resolves spontaneously after 1-2 years after onset Microscopically: band-like lymphocyte infiltrate in dermo-epidermal junction  Blisters (bullas) ○ May occur as secondary findings in unrelated conditions Herpes virus infection Spongiotic dermatitis Thermal burns ○ Presence is the most distinctive feature of several diseases in which some are uniformly fatal if untreated  Pemphigous ○ Cause in unknown and is triggered by various things ○ Most common trigger is drugs: sulfas, NSAIDs, ACE inhibitors such as lisinopril ○ Autoimmune disorder with loss of integrity of normal intracellular attachments within the epidermis and mucosal epithelium ○ Triggered by chemicals or drugs ○ Without treatment is life-threating ○ Others: pregnancy, stress, vaccines ○ Viral infections: H. Simplex, CMV, H. Pylori ○ Mostly occurs between 40-60 y/o ○ Equal incidence in both genders ○ Also can appear in conjunctiva, mouth ○ Loses integrity of its anatomical composition of the mucosa ○ ○ Ocular involvement in pemphigus vulgaris ○ Loss of mucosa- sinblepharon  Dermatitis herpetiformis ○ Characterized by urticaria and vesicles ○ More common in males (3rd-4th decade) and associated with celiac disease ○ Affected areas include the knees, back and buttocks ○ Non-inflammatory blistering diseases Epidermolysis bullosa ○ Blisters develop at site of pressure, rubbing or trauma ○ Porphyria ○ Uncommon inborn error of poryphyrin synthesis ○ Acne vulgaris ○ Begins in adolescence & males tend to have more severity of the disease ○ Virtually universal between middle to late teenagers ○ Two classifications: inflammatory vs. non-inflammatory / open vs. closed comedones  ○ Comedones: follicular papule with central black keratin plug Characteristic: black head and big abscesses ○ ○ Result from physiologic hormonal variation alteration in hair follicle maturation ○ Exacerbated by drugs: corticosteroids ○ Hormones: ACTH, Testoterone, FSH, LH, heavy clothing and tropical climate ○ Treated with hormones ○ Familial predisposition (?) Verrucae (wart) ○ Types: flat, palmaris, condyloma acuminatum (venereal) ○ Common lesion in childrean and adolescence associated with HPV infection ○ Transmission occurs by direct contact and are easy to transmit ○ Viral disease ○ Associated with development of squamous cell carcinoma of uterine cervix ○ Usually transmitted in surfaces, humidity (pools, baths) ○ Disorders of pigmentation Vitiligo ○ Common disorder with partial or complete loss of pigment produced by melanocytes ○ Asymptomatic; appears on hands, wrists, axilla, perioral, periorbital and anogenital ○ Etiology: autoimmune? ○ Freckle ○ Most common pigmented lesion in fair skin ○ Appear in early childhood after exposure to sun ○ Once present, they fade away and reappear ○ An increase in basal melanin ○ Melasma ○ Mask-like zone of facial hyperpigmentation (mask of pregnancy), changes in hormones ○ Usually resolves spontaneously particularly after the end of pregnancy ○ May occur with non-pregnant females with oral contraceptives ○ Most common appears in cheeks ○ Melanin deposited in basal and suprabasal keratinocytes intensely pigmented melanocytes, melanin within dermal melanophage- inflammation w/ pigmentation ○ Lentigo ○ Common benign localized hyperplasia of melanocytes occurring at all ages ○ Common to have circular shape, common in senile patient ○ An increase in basal melanin  Pigmented mole (nevocellular nevus) ○ Most humans have at least one or two, has defined borders* (circular in shape) ○ Describes a benign tumor composed of melanocytes ○ Usually is small, tan to brown papular lesion with well-defined rounded borders ○ ○ Classification Junctional Brown macule with central hyperpigmentation Nevus cells locate merely at the dermal-epidermal junction Compound Light to medium brown papule Nests appear both at the dermal-epidmeral junction and in the dermis Intradermal A light tan, soft raised papule Nests of nevus cells are situated in the dermis only Dysplastic nevi (BK moles) ○ Larger nevi (over 5 mm across) ○ Irregular borders, has different pigmentation inside of them too ○ Most are clinically stable ○ The probability of developing melanoma is 56% ○ Benign tumors of epithelial origin Seborrheic keratosis ○ Indolent lesion, more common in middle-aged subjects, comes from sebaceous glands ○ Grossly is appears coin-like plaque, some elevation (hyperkeratosis) ○ Treated by excision ○ Microscopically, the lesion is well demarcated and composed of proliferation of basaloid cells forming keratin cysts ○ Actinic keratosis ○ AKA solar keratosis ○ Scaly patch on the skin ○ Develops from years of sun exposure ○ Most important precursor to squamous cell carcinoma**** ○ Found on the face, lips, ears, forearms, scalp, neck or back of the hands, eyelids ○ Grow slowly usually after 40 y/o ○ Acanthosis nigricans ○ Thickened hyperpigmentation zones ○ Brown, velvety and verrucous plaques in axillae, back of neck and other skin fold ○ Benign type 80%, AD ○ Affects younger population, most commonly associated to insulin resistance patients ○ Obesity, insulin resistance, hormonal changes  ○ Epithelial cyst (wen) ○ Common lesion formed by down-growth and cystic expansion of the epidermis or epithelium forming the hair follicle ○ Misdx with abscesses/ sebeceous cysts, not part of epidermis ○ Waste material of the skin + lipid = opening in the superior area that will appear as a blackhead but not a blackhead ○ Cysts are filled with keratin and lipid debris ○ Keratoacanthoma ○ Rapidly developing neoplasm that mimic squamous cells carcinoma ○ More common in men but can also occur in females, over 50 y/o ○ Lesions appear in sun-exposed areas ○ Immunocompromised increase incidence: DM, autoimmune diseases ○ Histopathology: acanthosis (increased thickness) with hyperkeratosis and a central keratin crater ○ No keratinization**, not transmitted ○ Malignant Tumors of Epithelial Origin Squamous cell carcinoma ○ Malignancy of the stratum spinosum of the epidermis ○ Most common tumor arising in sun exposed areas in older people ○ More common in men  ○ Trend to ulcerate ○ Risk factors: workplace, genetic xeroderma pigmentosum (DNA replication disorder) ○ Basal cell carcinoma ○ Malignancy of the basal cell of the epidermis, most common carcinoma of the skin ○ Slow growing tumor affecting sun exposed areas ○ More common in whites ○ Grossly resembles as pearly pápales with sub epidermal blood vessels (telangiectasis) ○ Malignant pigmented tumor Melanoma ○ A form of skin cancer that begins in the melanocytes of the skin ○ Most common mortal skin cancer ○ Relatively common neoplasm surgically cured if detected at time ○ May arise anywhere in the body and is usually asymptomatic ○ Most important clinical sign is change in color of a pigmented lesion**** ○ May produce metastasis to lymph nodes, liver, lung and brain ○ MALIGNANT MELANOMA can look like a changing mole, spot that looks like a new mole, freckle or age spot, but it looks different from the others on your skin Spot that has a jagged border, more than one color, and is growing Dome-shaped growth that feels firm and may look like a sore, which may bleed Can go to the UVEA (iris, CB, and choroid) Dark-brown or black vertical line beneath a fingernail or toenail Band of darker skin around a fingernail or toenail Slowly growing patch of thick skin that looks like a scar Tumor progression Radial (horizontal growth) ○ Vertical (emergence of metastatic clone) * more risk to metastasis (biopsy confirms this) ○ Grows vertically down to dermis and if it gets to the blood vessels, there will be metastasis ○ The ABCDEs of Melanoma A = Asymmetry ○ One half of the spot is unlike the other half  ○ B = Border ○ Has an irregular, scalloped or poorly defined border ○ C = Color ○ Has varying colors from one area to the next, such as shades of brown, tan, or black, or areas of white, red, or blue ○ D = Diameter ○ While melanomas are usually > 6 mm, or about the size of a pencil eraser, when dx, they can be smaller ○ E = Evolving ○ Spot looks different from the ret or is changing in size, shape or color ○ Alopecia: refers to the loss of hair, concern for the patient is either cosmetic or psychological reasons. Comprise a large group of disorders w/multuple and varying etiologies. Sign of systemic disease Classification: focal, diffuse, patterned Scarring alopecia ○ Active destruction of the hair follicle and replaced by fibrotic tissue ○ Usually the result of infections, chemicals, burns or autoimmune disorders ○ Biopsy indicated ○ Non-scarring alopecia ○ Disorders that reduce or slow hair growth w/o irreparably damaging the hair follicle ○ Androgenic alopecia ○ An androgen-dependent hereditary disorder in which elevated dihydrotestosterone (DHT) plays a major role, most common one to see ○ Familiar predisposition ○ Treatment Minoxidil (2% for women, 5% for men) - shampoo Prolongs the anagen growth phase only 30 to 40% of patients experience significant hair growth *must be used for life) Finasteride 5 mg tab - more effective Inhibits the 5α-reductase enzyme, blocking conversion of testosterone to dihydrotestosterone, and is useful for male-pattern hair loss Also can be hyperplasia of the prostate for males Monitor levels of testosterone in females Surgical: follicle transplant, scalp flaps Phakomatoses: “phakomatosis” phakos, meaning birthmark (can appear on boards as they have ocular involvement) refers to a group of inherited disorders that affect the skin, connective tissue and nervous system, affect neurological tissue Neurofibromatosis 1 (NF1) is the most common tumor that appears- 1 in 3500 individuals worldwide Also known as neurocutaneous syndromes Could appear in the retina as retinal hamartoma (14%), retina achromic patch (2.5%), ON ○ First notice with changes of the skin Primarily involve structures derived from the embryological neuroectoderm These syndromes typically affect the CNS with glioma (tumors in the brain) Incidence ○ Affect males and females equally ○ Congenital conditions that cause tumors to grow inside the brain, spinal cord, organs, skin, and skeletal bone ○ in children, the most common manifestations are skin lesions  ○ The most common neurocutaneous syndromes ○ Tuberous sclerosis (TS)- common to appear in the face TSC 1 Hamartin (Chr: 9) TSC 2 Tuberin (Chr: 16) AD 1: 6000 Most are due to new mutations, tubers often grow inside (brain, retina, organs such as spinal cord, lungs, heart, kidneys, skin, skeletal, bones) Developmental delays Mental retardation, learning disabilities, seizures Two different skin patches appearance: Shagreen patches (thickening of the skin-flatter) ○ Ash leaf patches (hypopigmented lesions) ○  Retinal hamartoma Send patient to internal medicine doctor, grow in whitish color with some ovulated pattern Does not appear later in life, has had it since a child ○ Neurofibromatosis (NF) Type I and Type II AD 1:4000 (CHR 17) 50% due to new mutation (cafe con leche appearance) ○ Sturge-Weber Disease (sporadic) Classic symptoms is a congenital port-wine stain* located on the face, near or around the eye and forehead areas - follows trigeminal nerve may be associated brain abnormalities on the same side of the brain as the face lesion Neurological changes: seizures, muscle weakness, hemangiomas (choroidal, conjunctival, episcleral), changes in vision, congenital glaucoma, mental retardation Unlike TS and NF, other organs of the body are spared Dx tests: blood tests, genetic testing X-Ray, MRI, CT, EEG, EE, biopsy of the tumor or skin lesion  Hemangiomas in the choroid (Common to present) Can also present in lacrimal gland Neurofibromatosis Type I Von Recklinghausen’s Disease, common to find in clinic (Type 1) The most common form, the classic symptoms include: ○ Cafe-au-lait spots (can be one or multiple hyperpigmentation respecting the midline) Most common to appear in buttocks ○ Neurofibromas of nerves and organs (follows a peripheral nerve)  Soft, skin-colored pápale or small subcutaneous nodule, they arise from peripheral nerve sheaths A high rate of brain tumors in patients associated with NF 10-15% will have malignant changes in the neurofibromas with trauma, sun trauma Severe case of Neurofibromatosis Ocular Signs in NF 1 Subcutaneous ○ Plexiform neurofibroma of eyelid or intro orbital neurofibromas ○ ○ Proptotic eye  Uveal melanocytic nevi ○ Lisch nodules in 94-97% of patients > 6 y/o Retinal glial hamartomas Congenital glaucoma Optic nerve glioma ○ pill cystic astrocytoma Pulsating exophthalmos ○ due to absence of the sphenoid wing ○ Pulsating Exophthalmos Optic Glioma Guidelines for therapy include ○ Stable intro orbital tumor, good vision = observation ○ Stable intraorbital tumor, no painful = observation ○ Disfiguring proptosis (and poor vision) = excision of whole eye ○ Optic chasm threatened with advancing tumor (increasing in size) = excision of whole eye ○ Radiotherapy and chemotherapy have been used but results are inconclusive Looks like papilledema but is not ○ Patient has been seeing worse since birth- already has had tumor ○ Papilledema- loss of vision, related to viral or inflammatory conditions and is onset Lisch nodules Small iris melanocytic hamartomas (tumors) Tumors that grow over the iris, can be brown or yellow in color  May appear around adolescence Hearing loss, HA, seizures, scoliosis, and facial pain or numbness may also be present Mental retardation is present in 2-5% Others: may have learning problems and hyperactivity Neurofibromatosis Type II 2-5% of cases, AKA bilateral acoustic Neurofibromatosis Acoustic Neuroma ( CN VIII, CN VII affected) How to differentiate: facial and vestibular cochlear nerve (ear) ○ Schwann cells VIII CN, hearing loss noted as early as the teenage years HA, problems with facial movements, balance, and difficulty walking, loss of balance Other: seizures, neurofibromas, cafe-au-lait spots (less common as in NF I) Scleroderma: Systemic Sclerosis “Skleros” (hard or infuriated) and “derma” (skin) Progressive skin hardening and induction Scleroderma is an aspect of systematic sclerosis Systemic autoimmune disease of unknown origin Systemic connective tissue disease that also involves subcutaneous tissues muscles and internal organs Female-to-male ratio is 3:1 Peak age of onset is 40-60 years Pathophysiology: complex and involves an early endothelial damage, an inflammatory infiltrate and a resulting fibrotic reaction ○ accumulation of fibroblasts that makes the skin thicker ○ genetically and chronic inflammation that comes from autoimmune disorder Classification ○ Clinical subtypes Limited cutaneous scleroderma (IcSSc) Consists of morphea (oval lesions) and linear scleroderma Sclerotic lesions of the skin WITHOUT visceral involvement Diffuse cutaneous scleroderma (dcSSc)- can affect internal organs 1. CREST ○ Calcinosis cutis- calcium deposits in the skin ○ Raynaud phenomenon- spasm of blood vessels in response to cold or stress  ○ Esophageal dysmotility/dysfunction- acid reflux and decrease in motility of esophagus ○ Sclerodactyly- thickening & tightening of the skin on the fingers and hands ○ Telangiectasias- dilation of capillaries causing red marks on surface of skin Progression is slow Overall 10 yr survival ~65% Treatment: directed at symptoms and dysfunctional organs ○ NSAIDs can help arthritis ○ Corticosteroids may be helpful if they overt myositis or mixed connective tissue disease