Basic Skin Pathology PDF
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Dr. Rennan B. Navarro, M.D.
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This document provides information about the basic anatomy and histology of the skin, including its layers (stratum corneum, granulosum, spinosum, and germinativum/basale), and special cells such as melanocytes, Merkel cells, and Langerhans cells. It also covers epidermal appendages like hair follicles and sebaceous glands.
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PATHOLOGY 09/07/2024. MOD 5: BASIC SKIN PATHOLOGY...
PATHOLOGY 09/07/2024. MOD 5: BASIC SKIN PATHOLOGY Dr. Rennan B. Navarro, M.D. Trans Group/s: 1B STRATUM onsists of a single layer of C I. ANATOMY AND HISTOLOGY OF THE SKIN GERMINATIVUM tall cuboidal keratinocytes /BASALE that rest on a basement . EPIDERMIS A membrane. The epidermis consists of four layers except for the Innermost layer and thickskin, which hasfive layers mitotically active layer From the most superficial to the deepest layer of the (formation of new skin, the four layers of the skin are: keratinocytes) ○ stratum corneum Most immaturelayer ○ stratum granulosum ○ stratum spinosum ○ stratum germinativum/basale alpighian layer / Stratum malpighii (the nucleated M portion of the skin) is composed of 1. LAYERS OF EPIDERMIS Stratum spinosum Stratum germinativum/basale trictly speaking, malpighian layer refers to mitotically S active layers. Following this rule, only stratum germinativum is supposedly included in this layer; stratum spinosum was onlyincludedprobablybecause this layer is the starting point of keratin material production. ntheotherhand,whilethestratumgranulosumcontains O nucleated cells, it is NOT considered part of the Malpighian layer. Stratum granulosum is thelayerofthe epidermis where the nuclei starttobeextrudedfromthe celluntiltheycometoafullmaturity.Itbecomesastratum corneum where it becomes completelyDEVOIDof nuclei. 2. SPECIAL CELLS OF THE EPIDERMIS Layers of the epidermis. SPECIAL CELLS OF EPIDERMIS LAYERS OF THE EPIDERMIS 1 Melanocytes LAYERS Parameter 2 Merkel Cells STRATUM Outermostlayer 3 Langerhans Cells ORNEUM C nucleate or devoid of a A nucleus and some important organelles 2.1 Melanocytes Still composed of Specialized toproducemelanin,thebrownpigmentin keratinocytes ur skin o Most maturelayer They function to absorb and provide protection against potentially injurious UV radiation coming STRATUM he most distinctive feature is T from the sun GRANULOSUM thatthekeratohyalingranules Increases in number during sun exposure intheircytoplasmconsistof3 (photosensitive) to 5 layers of keratinocytes. Dispersed in the basal layer Ave no. of 1-10 in HE stain STRATUM onsists mainly of polyhedral C PINOSUM S keratinocytes that are arranged into several layers. “prickle cell layer” Consists of desmosomes that appear like spines (spines are referred to as “intercellular bridges”) Pathology - Mod 5 Skin Infections (Bacterial, Fungal, Parasitic) 1of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. Melanocytes. 2.2 Merkel Cells Irregularly distributed in the basal layer of theskin nd as well as in theoral mucosaandhair follicles a Serve as touch (tactile) ormechanoreceptors. Langerhans cells histology slide. Langerhan cells. 3. EPIDERMAL APPENDAGES EPIDERMAL APPENDAGES HAIR hair root is enclosed by two A FOLLICLE epithelial sheaths (external and internal root sheaths) Hairrootanditssheathscomprise Merkel cells. a hair follicle 2.3 Langerhans Cells SEBACEOUS he T sebaceous glands are GLANDS essentiallyappendages of hair Bone-marrow derived, dendritic, nd a Found in all areas where hair is ntigen-presenting cells(phagocytic function) a present Their number is relatively similar to that of the Simple branched alveolar glands melanocytes Decreasesin numberduring sun exposure CCRINE E umerous on thepalmsandsoles N Found in the supra-basal epidermis GLANDS Primary function is tohelpregulate Antigen-presenting cells (related to (MEROCRINE) body temperature monocyte/macrophage system) Simple coiled tubular glands APOCRINE oundonlyintheaxilla,aroundthe F GLANDS anus,andareolaofthebreast,and labia majora Only becomefunctional at puberty Coiled tubular glands NAILS eratinized epithelial cells that K form protective covers on the dorsal surfaces of the terminal ends of the digits . DERMIS B Underneath the epidermis Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 2of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. arbors the following: H . PATCH B 1. Dermal microvascular unit: vessels, nerves, Circumscribed lesion of> 5 mmin diameter migrant inflammatory cells Flatandusuallydistinguishedfromsurroundingskin 2. Dermalmuscle cells by its coloration 3. Dermalfibroblasts When macules coalesce, they become patch in 4. Dermallymphatics appearance 5. Extracellular matrix E.g. vitiligo, freckles . HYPODERMIS C Underneath the dermis Composed ofsubcutaneous tissue II. PROPERTIES OF THE SKIN . Maintains integrity of the body 1 2. Protects from injurious stimuli 3. Absorbs and excretes liquids 4. Regulates temperature 5. Water proofs Patch examples; (left) vitiligo; (right) a case of freckles with a 6. Absorbs UV light large involvement of the facial area. 7. Metabolize Vit. D 8. Detects sensory stimuli . PAPULE C 9. Provides cosmetic function Elevated dome-shapedorflat-toppedlesion≤5mm 10.Acts as a barrier against microorganisms across E.g. warts, nevi, dermal tumor, acne vulgaris, III. MACROSCOPIC TERMS IN DERMATOLOGY verruca vulgaris (common wart) MACROSCOPIC TERMS A Macule G Pustule B Patch H Wheal C Papule I Scale D Nodule J Lichenification Papules in Verruca (common wart). E Plaque K Excoriation . NODULE D F Blister (Vesicle and Bulla) L Onycholysis Elevated lesionwithspherical contour> 5 mmacross E.g. keratoacanthoma, appendagetumor,epidermal mm–reference sizeused to categorize skin lesions 5 inclusion cyst Legend:yellow highlight≤ 5 mm; blue highlight>5 mm Lesions that measure 5mmorLESSaredifferentiated through their other characteristics ○ Macule–flatdiscoloration of the skin ○ Papule–elevated/raised ○ Vesicle–raised/elevated, dome-shaped, fluid-filled Lesions that measureMOREthan 5 mm ○ Patch–flat ○ Nodule–elevated, dome-shaped, no fluid inside ○ Plaque–elevated, flat-topped ○ Bulla–elevated, dome-shaped, fluid-filled Nodule. . MACULE A . PLAQUE E Circumscribed lesion ofup to 5 mmin diameter Elevated, flat-topped areausually> 5 mmacross Flatandusuallydistinguishedfromsurroundingcells Raised, broad,andpalpable by its coloration Commonin patients withpsoriasis E.g.vitiligo, freckles E.g. psoriasis, seborrheic keratosis, mycosis fungoides Macule. Plaque. Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 3of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. . WHEAL H Itchy, transient, elevated areas with variable blanching and erythema formedasaresultofdermal edema Broad flaresofedematous skin E.g.urticaria, insect bites Seborrheic keratosis. F. BLISTERS (VESICLE AND BULLA) 1. VESICLE Fluid-filled raised (elevated, dome-shaped) area ≤ mm 5 E.g. herpes zoster, chicken pox, eczematous dermatitis Wheal. I. SCALE Dry, horny, platelike excrescences E.g. psoriasis, superficial fungal infections (dermatophytosis, tinea capitis, tinea corporis) Vesicles. 2. BULLA luid-filledraised area> 5mm F Biggerversion ofvesicle E.g.pemphigus vulgaris Psoriasis (left) and Tinea Capitis (right). . LICHENIFICATION J Thickened and rough skin with prominent skin markings E.g.lichen simplex, eczematous dermatitis Bulla. . PUSTULE G Discrete, pus-filled, raisedarea E.g.impetigo, acne vulgaris Lichenification. . EXCORIATION K Breakage of the epidermis caused by a traumatic lesion or infestation E.g.body louse infestation Pustule. Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 4of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. ypergranulosis H — keratinocytes; stratum granulosum Acanthosis— keratinocytes; entireepidermis Papillomatosis—papillary dermis Lentiginous—melanocytes; stratumbasale . HYPERKERATOSIS A Hyperplasia/thickening of thestratum corneum E.g.psoriasis,squamouscellcarcinoma,seborrheic keratosis, actinic keratosis, verruca vulgaris Excoriation, epidermis breakage (blue arrow). . ONYCHOLYSIS L Loss of integrityof thenail ○ “Onycho” = nail ○ “Lysis” =loss of integrityor loosening E.g.psoriasis Hyperkeratosis. . PARAKERATOSIS B Keratinization characterized by the retention of the nuclei due to therapidturnoverofkeratinocytesinthe skin(s tratum corneum) E.g.psoriasis, actinic keratosis, verruca vulgaris Onycholysis. IV. MICROSCOPIC TERMS IN DERMATOLOGY MICROSCOPIC TERMS A Hyperkeratosis H Lentiginous B Parakeratosis I Spongiosis C Hypergranulosis J Hydropic swelling Parakeratosis. D Acanthosis K Exocytosis . HYPERGRANULOSIS C Hyperplasia of thestratum granulosum E Dyskeratosis L Erosion Thekeratohyalinegranulesbecomemoreprominent andincrease in number F Acantholysis M Ulceration E.g.verruca, lichen simplex G Papillomatosis N Vacuolization Dermapath lesions that exhibithyperplasia in yellow Mnemonic:AHHPL (apple) take note of other P whichhas no L kin hyperplasias may be further differentiated through S the affected cells/layer: Hyperkeratosis— keratinocytes; stratumcorneum Hypergranulosis. Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 5of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. . ACANTHOSIS D Thickening of the entire epidermis secondary to hyperplasia (epidermal hyperplasia) E.g.verruca vulgaris; acanthosis nigricans Papillomatosis.Bluearrow points towards the papillary Acanthosis. dermal area.Jigsaw Puzzle Appearance. . DYSKERATOSIS E Abnormal keratinizationoccuringprematurelywithin individual cells (premature, abnormalkeratinizationof an individual keratinocyte) ○ Keratinocytes appearsdeeply eosinophilic ○ The more keratin = the more eosinophilic Usually signifiesunderlying skin malignancy of SCCa ○ Butitmayalsosignifyblooddyscrasiaspecifically aplastic anemia which is associated with dyskeratosis E.g. actinic keratosis, squamous cell carcinoma (SCCa) A Case of Verruca vulgaris showing 4 microscopic pathologic characteristics:hyperkeratosis,acanthosis,papillomatosis, hypergranulosis(the orange arrowmay or may not referto acanthosis) . LENTIGINOUS H Linear pattern of melanocyte proliferationwithinthe epidermal basal layer(stratum basale) E.g.,lentigo simplex Dyskeratosis. . ACANTHOLYSIS F Loss of intercellularconnectionsresultinginlossof cohesion between keratinocytes E.g.,pemphigus vulgaris (primary), impetigo Bluearrow points towards the linear proliferationof the melanocyte within the basal layer of the epidermis. Acantholysis. I. SPONGIOSIS INTERcellular edema of the epidermis . PAPILLOMATOSIS G Intact keratinocytes but the intervening stroma has Hyperplasiaof thepapillary dermis clearing or spacing out secondary to edema or E.g., verruca vulgaris accumulation of fluid E.g.,acute eczematous dermatitis Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 6of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. Parenchyma between cells is edematous and NOT the cells themselves. The keratinocytes are adherent to each other. . HYDROPIC SWELLING J INTRAcellular edema of keratinocytes The individual keratinocytes (tend to more ovoid/rounded) has clearing and enlargement of cytoplasmsecondary to edema or accumulation of fluid Seen in viral infections, especially by Papillomaviruses HPO view of epidermis infiltrated by inflammatory cells. . EROSION L Refers to discontinuity oftheskinshowingincomplete loss of the epidermis E.g., common finding among patients suffering from Steven-Johnson syndrome Hydropic Swelling. SPONGIOSIS VS HYDROPIC SWELLING Both of which refers to presence ofedema Erosion. SPONGIOSIS HYDROPIC SWELLING EROSION VS ULCER INTERcellular; swelling in INTRAcellular; swelling of the epidermis (intervening Both of which refers to thediscontinuity of the skin keratinocytes (cells itself) stroma) EROSION ULCER . EXOCYTOSIS K Infiltration of the epidermis by inflammatory cells or artiallossof C P omplete loss of epidermis(uptothe circulating blood cells the epidermis point that the ulcer or the lesion E.g.,inflammatory dermatoses, mycosis fungoides involves thedermal potion of the skin) Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 7of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. Erosion vs ulcer. . ULCERATION M Discontinuityoftheskinexhibitingcompletelossofthe Microscopic representation of the complete loss of epidermis epidermis. E.g.,basal cell carcinoma, squamous cell carcinoma . VACUOLIZATION N Formation of vacuoleswithin or adjacent to cells Hasclearing of the cytoplasm. E.g., koilocytosis in verruca vulgaris, basal cell vacuolation in LE(lupus erythematosus) Ulceration. Keratinocytes that have undergone vacuolization, showing the clearing of the cytoplasm. Ulceration of the foot. he figure above shows a foot showingcomplete loss T of epidermis.The muscles are already involved inthis condition. Keratinocytes that have undergone vacuolization, showing the clearing of the cytoplasm. VACUOLIZATION VS HYDROPIC SWELLING Both of which refers to theclearing of the cytoplasm VACUOLIZATION HYDROPIC SWELLING reaction to pathogens, A Brought about by especially viruses such as edematous process the human papillomavirus Genital of a male. The male genital organ shows chancre, which is c ommon among patients withsyphilis. Pathology - Mod 5 🏠Skin Infections (Bacterial, Fungal, Parasitic) 8of10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.
