ANDREWS DISEASES OF THE SKIN

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ANDREWSDISEASES OF THE SKIN

• Chapter 1
• The Skin Basic structure and function

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• Epidermis
• dermis
• Subcutaneous fat
• Considerable regional variation in their relative
  thickness

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epidermis

• Adnexal structures, particularly follicles and
  eccrine sweat units, originate during the third
  month of fetal life as down growths from the
  developing epidermis
• The adult epidermis is composed of three basic
  cell types
• Keratinocytes
• Melanocytes
• Langerhans cells

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Merkel cell

• Found in the basal layer of the palms and soles,
  the oral and genital mucosa, the nail bed, and
  the follicular infundibula
• Located directly above the BM
• Act as slow adapting touch receptors

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keratinocyte

• Principal cell of the epidermis
• Ectodermal origin
• Specialized function of producing keratin
• Divided into the following zones
• Basal layer
• Malphighian layer/prickle layer
• Granular layer
• Stratum corneum

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• As a cell moves upward through the epidermis it
  changes morphologically
• Variation in the thickness of the different zones
  of the epidermis according to skin site
• Basal cell layer is generally one cell thick
  regardless of site

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• During keratinization, the keratinocyte passes
  through a synthetic and degradative phase
• During the synthetic phase desmosomes are formed
• The degradative phase is marked by the
  disappearance of cell organelles and the
  consolidation of all contents into a mixture of
  filaments and amorphous cell envelopes

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• Odland bodies found intracellularly in
  upper-level keratinocytes
• Establish a barrier to water loss and with
  filaggrin mediate stratum corneum cell cohesion

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Melanocyte

• Pigment producing cell
• Derived from neural crest
• Found in the fetal epidermis in the eighth week
• Normally reside in the basal cell layer
  approximately one for every 10 basal
  keratinocytes
• Numbers are same regardless of race or color

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• Number and size of melanosomes determines skin
  color
• Don not form desmosomal attachments with
  keratinocytes
• Dendritic cell, in contact with a number of
  keratinocytes, forming the epidermal melanin unit

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• Melanosomes are synthesized in the Golgi zone
• Keratinocytes are the reservoir for melanin in
  the skin
• Melanocytes in dark skin synthesize melanosomes
  larger than those produced in light skin
• The size of the melanosome is the principal
  factor in determining how melanosomes will be
  distributed within the keratinocyte

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• Chronic sun exposure can stimulate the melanocyte
  to produce larger melanosomes
• Vitiligo destruction of melanocytes
• Albinism melanocyte number is normal, but
  because of a defect in the enzymatic formation of
  melanin they are unable to synthesize fully
  pigmented melanosomes

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The Langerhans Cell

• Normally found scattered among keratinocytes in
  the stratum spinosum/prickly cell layer
• Constitute 3-5 of cells in this layer
• No desmosome connections
• gold chloride appear as dendritic cells
• Characterized by a folded nucleus and distinct
  intracytoplasmic organelles called Birbeck
  granules, which resemble a tennis racquet

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• Functionally are of the monocyte-macrophage
  lineage and originate in bone marrow
• Role in induction of graft rejection, primary
  contact sensitization, and immunosurveillance
• Function primarily in the afferent limb of the
  immune response by providing for the recognition,
  uptake, processing, and presentation of antigens
  to sensitized T lymphocytes

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The Epidermal-Dermal Junction

• The junction of the epidermis and dermis is
  formed by the BMZ
• Composed of four compartments
• Plasma membranes of the basal cells
• Lamina lucida
• Basal lamina
• Fibrous components associated with the basal
  lamina

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• BMZ is a semipermeable filter
• Serves as structural support

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Epidermal Appendages The Adnexa

• Eccrine and apocrine glands and ducts
• And pilosebaceous units
• Originate as down growths from the epidermis
• Various adnexal structures serve specific
  functions
• All can functions as reserve epidermis, occurring
  principally by virtue of migration

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The Eccrine Sweat Unit

• Composed of three sections
• Acrosyringium, intraepidermal component, opens to
  the skin surface, called the spiral duct
• Straight duct, dermal portion
• Secretory acinar portion, or coil gland, found
  within the panniculus near the junction of he
  dermis and the subcutaneous fat

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• Found at virtually all skin sites
• Most abundant on the palms, soles, forehead, and
  axillae

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The Apocrine unit

• Apocrine unit develops as outgrowths of the upper
  portion of the hair follicle
• Straight excretory portion of he duct, opens into
  the infundibular portion of the hair follicle
• The coiled secretory gland is located at the
  junction of the dermis and the subcutaneous fat
• Composition of the product of secretion is only
  partially understood

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• Secretion is mediated through adrenergic
  inervation
• While secretion of the gland is continuous
  excretion is episodic
• Gland secretion in humans serves no known
  function
• Generally confined to axillae, areolae,
  anogenital region, EAC and the glands of Moll on
  the eyelids
• Do not begin to function until puberty

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The Hair Follicle

• The uppermost portion of the follicle extends
  from the surface opening to the entrance of the
  sebaceous duct, infundibular segment
• Isthmus, is the portion of the follicle between
  the duct and the insertion of the erector pili
  muscle
• The matrix includes the lowermost part of the
  follicle and the hair bulb

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• The hair shaft, as well as the inner and outer
  root sheath, develops from the mitotically active
  undifferentiated cells of the matrix portion of
  the hair bulb
• The hair shaft and the inner root sheath move
  together as the hair grows
• The outer root sheath remains fixed

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• The cross-sectional shape of the hair depends on
  the arrangement of cells in the bulb
• Basic hair color depends on the distribution of
  melanosomes within hair bulb cells
• Larger melanosomes are found in the hair of
  blacks
• Red hair is characterized by spherical
  melanosomes
• Graying of hair results from decreased melanocyte
  numbers

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• Anagen
• Catagen
• Telogen
• Average period of growth of scalp hair is 3 to 4
  years, involutional and resting phases last
  approx 3 months
• 85 to 90 of scalp hairs are in anagen phase

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The Sebaceous Gland

• Formed embryologically as an outgrowth from the
  upper portion of the hair follicle
• Found in greatest abundance on the face and scalp
• Distributed throughout all skin sites except
  palms and soles

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• Always associated with hair follicles except at
  at the following sites
• Eyelids (meibomian glands)
• Buccal mucosa and vermilion border of the lip
  (Fordyces spots)
• Prepuce (Tysons glands)
• Female areolas (Montgomerys tubercles)

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The Nails

• Matrix keratinization leads to the formation of
  the nail plate
• Keratin types found in the nail are a mixture of
  epidermal and hair types
• Fingernails grow an average of 0.1 mm/day, slower
  for toenails
• Abnormalities may serve as important clues to
  cutaneous and systemic disease

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The Dermis

• The constituents of the dermis are of mesodermal
  origin, with the exception of nerves
• By the 12th week of fetal life fibroblasts are
  actively synthesizing reticulum fibers, elastic
  fibers, and collagen
• The principal component of the dermis is collagen
• This serves as the major structural protein for
  the entire body
• Represents 70 of the dry weight of the skin

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• The fibroblast synthesize procollagen molecules
  that are secreted and assembled into collagen
  fibrils
• Collagen is rich in the amino acids
  hydroxyproline, hydroxylysine and glycine
• Collagen fibers are loosely arranged in the upper
  dermis
• Tightly bundled in a fascicle-like pattern in the
  lower dermis

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• Type IV collagen is found in the BMZ
• Type VII collagen is the major structural
  component of anchoring fibrils and is produced
  predominantly by keratinocytes
• Fibroblast also synthesize elastic fibers, as
  well as the ground substance of the dermis
• Amino acids desmosine and isodesmosine are unique
  to elastic fibers

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• Collagen is the major stress-resistant material
  of the skin
• Elastic fibers contribute very little to
  resisting deformation and tearing of the skin,
  but have a role in maintaining elasticity

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• Defects in collagen synthesis
• Ehlers-Danlos syndrome
• X-linked cutis laxa
• Osteogenesis imperfecta
• Defects in elastic tissues

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Vasculature

• Consists principally of two intercommunicating
  plexuses
• Subpapillary plexus/upper horizontal network
• Lower horizontal plexus

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Muscles

• Smooth muscle occurs in the skin as arrectores
  pilorum, as the tunica dartos of the scrotum ,
  and in the areolas around the nipples
• Striated muscle occurs in the skin of the neck as
  the platysma and in the skin of the face as the
  muscles of facial expression
• Glomus bodies, specialized aggregates of smooth
  muscle cells found between arterioles and venules

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Nerves

• Dermis is rich in nerves
• Meissner corpuscles, touch and pressure
• Vater-Pacini corpuscles
• Temperature, pain and itch sensation are
  transmitted by unmyelinated nerve fibers which
  terminate in the papillary dermis and around hair
  follicles

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Mast Cells

• 6-12 microns in diameter
• Contain up to 1000 granules
• cell surface contains glycoprotein receptor sites
  for IgE
• High content of heparin
• Also contain histamine, neutrophil chemotactic
  factor, eosinophil chemotactic factor of
  anaphylaxis, tryptase, kininogenase, and
  betaglucoseaminidase

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Dermal Dendrocyte

• Possesses phenotypic characteristics of
  macrophages
• Found in a perivascular network and may serve as
  an antigen presenting cell

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Subcutaneous Tissue

• Beneath the dermis lies the panniculus
• Subcutaneous tissue thickness varies
• Panniculitides affect this level of the skin
• The pattern of inflammation, specifically whether
  it primarily affects the septa or the fat lobules
  themselves, serves to distinguish the various
  conditions

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CUTANEOUS SYMPTOMS,SIGNS, AND DIAGNOSIS

• Chapter 2

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• The same disease may show variations under
  different conditions and in different individuals
• Appearance of lesions may have been modified by
  previous treatment or obscured by extraneous
  influences (scratching, secondary infection)
• Subjective symptoms may be the only evidence of
  disease

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CUTANEOUS SYMPTOMS
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• Pruritis
• Burning
• Tingling
• Prickling
• Biting
• Formication
• Pain
• numbness

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Pruritis

• An unpleasant cutaneous sensation which provokes
  the desire to scratch or rub the skin
• Most common cutaneous symptom
• Carried from the skin by unmyelinated C fibers
• The quality of the itch may be useful in
  determining the diagnosis

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• Regional and individual differences in the
  perception of and the reaction to pruritis
• May be in part related to the psychologic state
  at the time
• The anogenital area is especially prone to
  pruritis
• Xerosis
• Pruritis with HIV and AIDS

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• Pruritis with systemic disease
• Hepatobiliary diseases, especially biliary
  obstructive disease, severe renal insufficiency,
  iron-deficiency anemia, endocrine disorders, and
  internal malignancy (especially lymphoma)

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• Thyroid dysfunction
• Less commonly parathyroid
• DM
• Is typically generalized when associated with
  renal failure (uremic pruritis)
• Often associated with the appearance of
  hyperkeratotic prurigo nodulelike lesions
• Kyrles disease/perforating disorder of renal
  failure or dialysis

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• Pruritis of live disease
• An associated hepatitis C virus infection should
  always be sought
• Opiate antagonists may improve this form of
  pruritis
• Antidepressants, belladonna, alkaloids, opiates,
  and oral contraceptives may induce pruritis
• Recreational drugs (amphetamines and cocaine)

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• Psychologic disease
• Most frequently anxiety/depression
• Or obsessive compulsive disorder
• Treat the underlying disorder

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Other symptoms

• Pain
• Allodynia, production of pain by normally trivial
  stimuli, PHN
• Hypesthesia and hyperesthesia
• Loss of specific sensations, Hansens disease and
  follicular mucinosis
• Reversal of the perception of heat and cold,
  Ciguatera fish poisoning

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CUTANEOUS SIGNS
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PRIMARY LESIONS

• Macules, patches, papules, plaques, nodules,
  tumors, wheals, vesicles, bullae, and pustules

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Macules

• Variously sized
• Circumscribed changes in the skin color
• Without elevation or depression
• Circular oval or irregular

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Patches

• A large macule
• 1 cm or greater in diameter
• Nevus flammeus or vitiligo

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Papules

• Circumscribed, solid elevations, with no visible
  fluid, varying in size from pinhead to 1 cm
• May be acuminate, rounded, flat-topped, conical,
  or umbilacated
• Variety of colors
• May be soft or firm
• Papulosquamous, when capped by scales

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• May be discrete and irregularly distributed or
  grouped
• Some persist and some progress

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Plaques

• A broad papule or a confluence of papules
• 1 cm or more in diameter
• Generally flat but may be depressed

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Nodules

• Morphologically similar to papules
• More than 1 cm in diameter
• Most frequently are centered on the dermis or the
  subcutaneous fat

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Tumors

• Soft or firm freely moveable or fixed masses
• Various sizes and shapes
• Generally greater than 2 cm in diameter
• Elevated or deep seated
• Pedunculated

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Wheals

• Evanescent, edematous, plateaulike elevations of
  various sizes
• Usually oval or arcuate contours
• Pink to red
• Surrounded by a pink areola
• May be discrete or coalesce

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Vesicles

• Circumscribed, fluid-containing, epidermal
  elevations 1 to 10 mm
• Pale or yellow from serous exudate, or red
• Apex may be rounded, acuminate, or umbilacated
• Discrete, irregularly scattered, grouped or
  linear
• May develop into bullae or pustules
• Vesicopustules
• Unilocular or multilocular

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Bullae

• Rounded or irregularly shaped blisters containing
  serous or seropurulent fluid
• Differ from vesicles only in size, being larger
  than 1 cm
• Typically unilocular
• May be located superficially in the epidermis or
  subepidermal

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• Nikolskys sign, diagnostic maneuver of putting
  lateral pressure on unblistered skin in a bullous
  eruption with shearing of the epithelium
• Absoe-Hansens sign, extension of a blister to
  adjacent unblistered skin when pressure is put on
  top of the blister
• Cellular contents of the bullae may be useful in
  confirming the diagnosis

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Pustules

• Small elevations of the skin containing purulent
  material (usually necrotic inflammatory cells)
• Similar to vesicles and have an inflammatory
  areola
• White, yellow or red if they contain blood
• May originate as pustules or develop from papules
  or vesicles

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SECONDARY LESIONS

• Scales, crusts, erosions, ulcers, fissures, and
  scars

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Scales

• Dry or greasy laminated masses of keratin
• When the formation of epidermal cells is rapid or
  the process of normal keratinization is
  interfered with, pathologic exfoliation results,
  producing scales
• Vary in size
• Vary in color

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• May have a silvery sheen from trapping of air
  between their layers these are micaceous scales,
  characteristic of psoriasis

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Crusts

• Crusts are dried serum, pus, or blood, usually
  mixed with epithelial and sometimes bacterial
  debris
• Vary greatly in size, thickness, shape and color,
  according to their origin, composition and volume
• When they become detached the base may be dry or
  moist

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Excoriations and abrasions

• An excoriation is a punctate or linear abrasion
  produced by mechanical means, usually involving
  only the epidermis, but not uncommonly reaching
  the papillary layer of the dermis
• Caused by scratching
• If the damage is a result of mechanical trauma or
  constant friction abrasion
• Frequently has an inflammatory areola
• May provide access for pyogenic organisms

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Fissures

• A fissure is a linear cleft through the epidermis
  , or into the dermis
• May be single or multiple
• Microscopic to several centimeters in length
• Sharply defined margins
• May be dry, moist, red, straight, curved,
  irregular, or branching

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Erosions

• Loss of all or portions of the epidermis alone
• May not become crusted
• Heals without a scar

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Ulcers

• Rounded or irregularly shaped excavations that
  result from complete loss of the epidermis plus
  some of the portions of the dermis
• Various sizes, shallow or deep
• Heal with scarring

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Scars

• Composed of new connective tissue that replaced
  lost substance in the dermis or deeper parts as a
  result of injury or disease, as part of the
  normal reparative process
• Characteristic of certain inflammatory processes
• Scars may be thin and atrophic or keloids
• May be smooth or rough, pliable or firm
• Pink initially, later becoming white and
  glistening

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GENERAL DIAGNOSIS
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history

• Patients age, health, occupation, hobbies, living
  conditions
• Onset, duration and course of the disease
• Previous treatment
• Family history
• Drug history
• Other illness, travel abroad, home and work
  environment, seasonal occurrences and recurrences
• Sexual orientation and practices

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examination

• Natural sunlight is ideal
• Fluorescent bulbs that produce wavelengths of
  light closer to natural sunlight
• Woods light
• Magnifying lens
• Palpation
• Scraping
• View entire eruption, no Peek-a boo exam

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Diagnostic Details of Lesions
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distribution

• Lesions may be few or numerous, and in
  arrangement they may be discrete or may coalesce
  to patches of peculiar configuration
• Lines of cleavage PA
• Dermatomes Zoster
• Blaschkos lines epidermal nevi

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evolution

• Some lesions appear fully evolved
• Others develop from smaller lesions, then may
  remain the same during their entire existence
• A polymorphous eruption with lesions in various
  stages of development or involution may be
  present , varicella

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involution

• Lesions may disappear completely
• May leave characteristic residual pigmentation or
  scarring

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grouping

• Characteristic of DH, herpes simplex, herpes
  zoster, and late syphilitic eruptions
• Corymbose, small lesions around a larger one
• Linear (breakfast-lunch-and-dinner), flea and
  other arthropod bites
• Agminated, grouped lesions of various sizes

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configuration

• Linear, lesion in a line
• Annular, forming a complete circle
• Arcuate, portion of a circle
• Polycyclic, composed of several intersecting
  portions of circles
• Serpiginous, not straight but not forming parts
  of circles
• Guttate, small, like drops
• Nummular, larger, like a coin
• Unusual configurations may be exogenously induced

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color

• The Tyndall effect modifies the color of the skin
  and the color of the lesions by the selective
  scattering of light waves of different
  wave-lengths. The blue nevus and mongolian spots
  are examples of this light dispersion effect
• Not advisable to place too much reliance on color

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• Patches lighter in color than normal skin may be
  completely depigmented or have lost only part of
  their pigment
• Hyperpigmentation may be a result of epidermal or
  dermal causes
• Hyperpigmentation following inflammation is most
  commonly the result of dermal melanin deposition

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consistency

• Palpation is an essential part of the physical
  examination of lesions
• Blanch? Fluctuant? Hot or cold? Firm or
  calcified? Brawny? Doughy?

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Cutaneous Findings in Systemic Disease

• At times an unusual skin eruption may be a clue
  to some internal disorder that may not be obvious.

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nodules

• Subcutaneous or dermal metastatic nodules are
  common and easily detected manifestations of
  metastatic carcinoma
• Most favored site is trunk or scalp
• Frequently metastases are from carcinoma of the
  breast, GI tract, melanoma, ovary, uterus
• Sister Mary Josephs nodule

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• Multicentric reticulohistiocytosis, internal
  malignancy may be present in up to 25 of cases
• Gardners syndrome, fibromas, epidermoid cysts,
  osteomas, and desmoid tumors

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vascular lesions

• Petechiae, ecchymoses, pinch purpura and caput
  medusae are some of the vascular lesions
  associated with malignancies
• pinch purpura, primary systemic amyloidosis of
  the skin
• systemic steroid treatment ma result in easy
  bruisability

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flushing

• Episodic flushing, especially on the face,
  lasting some 10 to 30 minutes, is a consistent
  sign of carcinoid syndrome
• Bronchial carcinoid tumors

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pruritis

• Generalized pruritis may be seen in many
  myeloproliferative diseases, but it is most
  characteristic or lymphoma or polycythemia vera
• Liver disease, renal failure, iron deficiency,
  thyroid or parathyroid disease

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eczema

• Unilateral eczematous eruption on one nipple, may
  be Pagets disease of the breast with underlying
  intraductal carcinoma
• Early manifestation of MF may resemble an eczema
• Bazexs syndrome, an eczematous eruption
  involving the hands, feet, nose, and ears, a sign
  of an underlying malignant neoplasm of the
  aerodigestive tract

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vesicles and bullae

• Dermatitis herpetiformis
• Associated with a usually asymptomatic
  gluten-sensitive enteropathy
• Increased risk for the development of
  gastrointestinal lymphoma
• zoster

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erythroderma

• Universal erythroderma, generally accompanied by
  scaling, may be associated with malignancy,
  usually lymphoma
• Characteristic of Sezary syndrome
• Severe drug eruption may be the cause

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erythema and edema

• Erythema, edema, and purple discoloration of the
  eyelids, indicative of dermatomyositis
• Gottrons papules
• Skin lesions can precede the myositis by weeks to
  years

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• Tender, erythematous, edematous plaques that may
  centrally vesiculate on the upper part of the
  body associated with fever and leukocytosis
  characterize Sweets syndrome
• May be presenting sign of myelogenous leukemia

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erythematous nodules

• Erythema nodosum may rarely be associated with
  Hodgkins disease and metastatic carcinoma
• Most common cause is preceding streptococcal
  pharyngitis

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hyperkeratosis

• Sezarys erythroderma, Hodgkins disease,
  lymphocytic leukemia and Bazexs syndrome may be
  accompanied by hyperkeratosis of the palms and
  soles
• Howel-Evans syndrome, a hereditary esophageal
  carcinoma syndrome

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hyperpigmentation

• Diffuse melanosis cutis, in metastatic melanoma.
  Melanuria is also present
• Pituitary tumors
• Addisons disease
• Hemochromatosis and arsenic intoxication, bronze
  hyperpigmentation
• Acanthosis nigricans

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alopecia

• When follicular mucinosis occurs in lesions of
  mycosis fungoides, affected areas on the scalp or
  beard may present with sharply circumscribed
  plaques of alopecia
• May also occur in syphilis, thyroid disease, and
  iron deficiency

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hirsutism and hypertrichosis

• Adrenal or ovarian carcinomas maybe the cause of
  excessive hair growth
• Malignant down is an excessive growth of
  lanugo-like hair, which is assoc with malignant
  disease of the lung, colon, gallbladder, and
  uterus

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urticaria

• Hodgkins disease may be accompanied by urticaria
• Cold urticaria with cryoglobulinemia is seen in
  multiple myeloma

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sulfer-yellow plaques on the shins

• Necrobiosis lipoidica (with or without diabetes)
  presents as bilateral, well-defined plaques with
  a smooth, glistening surface and yellow color

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The end