Pathology of the Dermis I Flashcards
(72 cards)
1
Q
What is a papule?
A
- a small, elevated, palpable solid lesion
- usually less than 5mm in diameter
2
Q
what is a macule?
A
- flat, discolored area on the skin that is not raised or depressed
- usually 5mm or smaller
3
Q
what is a patch?
A
- flat, discolored area on the skin that is not raised or depressed
- usually GREATER than 5mm
4
Q
what is a nodule?
A
- elevated, solid lesion
- larger than 5 mm in diameter
5
Q
What is a plaque?
A
- elevated, flat-topped area
- usually greater than 5 mm in diameter
6
Q
What is the difference between a vesicle, a bulla, and a blister?
A
- Blister: is a general term that refers to any fluid-filled lesion
- Vesicle: fluid-filled, raised lesion, up to 5 mm in diameter
- Bulla: fluid-filled, raised lesion, greater than 5 mm in diameter
7
Q
What is a pustule?
A
pus-filled raised lesion that is typically small and can occur in conditions like acne and folliculitis
8
Q
What is the difference between lichenification, scaling, and crusting?
A
- Lichenification: Thickened, leathery skin with prominent skin lines due to chronic scratching or rubbing
- Scaling: Flaking or shedding of dead skin cells from the epidermis
- Crusting: Dried exudate (blood, serum, or pus) on the skin surface, forming a scab-like layer
9
Q
what is Dyskeratosis?
A
microscopic term for abnormal keratinization occurring prematurely in cells below the stratum granulosum
10
Q
what is Acantholysis?
A
microscopic term for loss of intercellular connections between keratinocytes
11
Q
what is Spongiosis?
A
microscopic term for epidermal intercellular edema
12
Q
what is Acanthosis?
A
microscopic term for diffuse epidermal hyperplasia (thickening of epidermis)
13
Q
what is Erosion?
A
microscopic term for discontinuity of the skin with incomplete loss of the epidermis
14
Q
what is ulceration?
A
microscopic term for discontinuity of the skin with complete loss of the epidermis and often portions of the dermis and subcutis
15
Q
what is Hyperkeratosis?
A
microscopic term for thickening of the stratum corneum by abnormal keratin
16
Q
what is Parakeratosis?
A
retention of nuclei in the stratum corneum (outermost layer of the epidermis), which normally should be anucleate
17
Q
what are inflammatory dermatoses?
A
skin conditions caused by local or systemic immune responses leading to inflammation
- can be chronic or acute
18
Q
what is the difference between acute and chronic inflammatory dermatoses lesions?
A
- Acute Lesions: last days to weeks, cause inflammation, edema (swelling), epidermal and vascular injury and mainly involve mononuclear cells (like lymphocytes and macrophages)
- Chronic Lesions: last months to years, cause significant changes in skin structure such as atrophy (thinning) or hyperplasia (thickening) of the epidermis, and dermal fibrosis (scarring)
19
Q
What is Acute Dermatosis (Urticaria)?
A
common local skin allergic reaction affecting all ages (mainly 20-40s) causing pruritic edematous plaques and papules called WHEALS
- can be linked to angioedema (emergent)
20
Q
what are the two mechanisms that can cause Urticaria and how are they different?
A
- Type I Hypersensitivity Reaction (IgE-dependent): IgE antibodies produced in response to antigens (pollens, foods, drugs, insect venoms) bind to mast cells, triggering vasoactive mediator release
- IgE-independent: direct mast cell degranulation without IgE mediation from substances like opiates, antibiotics, radiographic materials, and aspirin
21
Q
What are the lesion characteristics and common sites of Urticaria?
A
- lesions develop and fade within hours but episodes can last days or months
- develop on sites exposed to pressure
22
Q
what are the microscopic findings of Urticaria?
A
- Skin may appear normal under microscopy (telling sign)
- Superficial perivascular infiltrate of mononuclear cells, neutrophils, and eosinophils is observed.
- Dermal Edema: increased space between collagen fibers reflects tissue swelling
- Dilated Lymphatic Channels
23
Q
What is Acute Eczematous Dermatitis?
A
- group of disorders characterized by red, papulovesicular, oozing and crusted lesions that with time develop into raised scaling plaques
24
Q
what are the classifications of Acute Eczematous Dermatitis?
A
- Allergic contact dermatitis
- Atopic dermatitis
- Drug-related eczematous dermatitis
- Photoeczematous dermatitis
- Primary irritant dermatitis
25
what is the mechanism that causes Acute Eczematous Dermatitis?
Type IV Hypersensitivity Reaction (T-cell Mediated)
- antigens are taken up by dendritic cells and langerhans at the epidermal surface
- migrate through lymphatics into the lymph nodes
- antigens are presented to naive CD4 T cells which develop effector and memory T cells
- antigen re-exposure cause cytokine release to recruit inflammatory cells
26
What is a clinical example of Acute Eczematous Dermatitis?
- topical agent (poison ivy, laundry detergent, etc) cause pruritic edematous oozing plaques that often contain blisters (vesicles and bullae)
- persistant lesions become less wet (fail to ooze) and become progressively scaly (hyperkeratotic and acanthotic)
27
what are the microscopic findings of Acute Eczematous Dermatitis?
- Spongiosis of the epidermis that may result in intraepidermal vesicles or blister formation
- Superficial perivascular lymphocytic infiltrate, dermal edema and eosinophils
28
what is Erythema Multiforme?
uncommon acute dermatosis hypersensitivity reaction effecting individuals of any age usually from infections (herpes, mycoplasma, etc) or drugs (sulfonamides, penicillin, etc)
29
what is the mechanism that causes Erythema Multiforme?
- Cytotoxic T-cell-mediated destruction
- CD8+ cytotoxic T lymphocytes attack and destroy epidermal cells, leading to tissue damage
- Target antigens for this immune response are not clearly identified
30
what are the clinical features of Erythema Multiforme?
- Multiform lesions: macules, papules, vesicles, and bullae, often with a distinct target lesion appearance
- typical target lesion has a red macule or papule with a pale, vesicular, or eroded center
- Lesions are generally symmetrical and found on both extremities
31
what are the two severe variants of Erythema Multiforme?
1. Stevens-Johnson Syndrome (SJS): involving mucosal sites (oral, conjunctiva, genital) with hemorrhagic crusts accompanied by widespread lesions and systemic symptoms
2. Toxic Epidermal Necrolysis (TEN): most severe variant, characterized by diffuse necrosis and sloughing of skin, involves more than 10% of the total body surface area and affects mucosal epithelial surfaces
32
what are the microscopic findings for Erythema Multiforme?
- Lymphocyte Accumulation: at the dermoepidermal junction, associated with degenerating and necrotic keratinocytes
- Perivascular Infiltration: superficial lymphocytic infiltrate is present with dermal edema
- Lack of Chronic Changes: no evidence of epidermal atrophy, hyperplasia, or hyperkeratosis
33
what is Psoriasis?
common chronic inflammatory dermatoses affecting all ages and commonly infecting the skin of elbows, knees, scalp, lumbosacral areas, intergluteal cleft and glans penis
34
what diseases can Psoriasis be associated with?
arthritis, myopathy, enteropathy, spondylitic joint disease or HIV
35
what is the mechanism that causes Psoriasis?
autoimmune disease caused by a malfunction of the immune system where T cells become overactive and release cytokines, promoting inflammation, rapid growth of skin cells and increased blood flow
**Treatment Strategies focused on inactivating T cells to reduce hyperproliferation of the skin
36
what are the clinical features of Psoriasis?
- lesions are well-demarcated, pink to salmon-colored plaques covered with silver-white scales that bleed when removed (Auspitz sign)
- Erythroderma: Psoriasis can extend to cause total body erythema and scaling.
- Nail Changes (30% of cases): yellow-brown discoloration, pitting, dimpling, onycholysis (nail separation), thickening, and crumbling
37
what are the microscopic features of Psoriasis?
- Acanthosis: thickening with downward elongation of the rete ridges.
- Parakeratosis: granular layer of the epidermis is either thinned or absent.
- Suprapapillary Thinning: thin plates overlying the dermal papillae, which increases vulnerability.
- Munro Microabscesses: clusters of neutrophils in the parakeratotic scale, visible as microabscesses
38
what is Lichen Planus?
a self-limiting inflammatory disorder affecting the skin and mucous membranes
39
what are the clinical features of Lichen Planus?
- Itchy, violaceous (purple-colored), flat-topped papules that can coalesce to form plaques.
- **Wickham striae (white dots or lines on the surface)
- typically affects the wrists, elbows, and glans penis.
- lesions are usually symmetrically distributed
- Mucosal Lesions appear white and reticulated, commonly found in the mouth
40
What is the mechanism that causes Lichen Planus?
Exact cause is unknown but suspected to involve immune-mediated mechanisms like
- Hepatitis B
- Hepatitis C
- HIV
- some drugs
41
what are the microscopic findings of Lichen Planus?
- Interface Dermatitis: dense lichenoid lymphocytic infiltrate along the dermoepidermal junction associated with degenerated and necrotic keratinocytes
- Saw-Toothing of Rete Ridges: dermoepidermal interface forms a zigzag (saw-tooth) pattern
- Colloid (Civatte) Bodies: represent anucleate necrotic keratinocytes within the papillary dermis.
- Chronic Changes: epidermal hyperplasia, hypergranulosis, and hyperkeratosis
- Bandlike Infiltrate: lymphocytes accumulate in a bandlike pattern at the dermal-epidermal junction
42
what are Blistering Diseases?
A group of skin conditions where the primary feature is the formation of vesicles (small blisters) or bullae (large blisters) that create a dramatic clinical picture and can be life-threatening if untreated
43
how are Blistering Diseases classified?
the level of separation and depth of the blister within the skin layers is crucial to identify the specific type
44
what are the three levels of blister formations used for diagnosing Blistering Diseases?
- Subcorneal: below the stratum corneum (outermost skin layer), primarily in the granular layer
- Suprabasal: above the basal layer, including the stratum corneum and the roof of the blister is formed by the upper epidermis
- Subepidermal: entire epidermis separates from the dermis, forming deeper, more robust blisters
45
what is Pemphigus?
An autoimmune disorder that results in the loss of intercellular adhesions (acantholysis) between epithelial cells of the epidermis and mucosa that affects people typically in their 40s to 60s and affects both genders equally
46
what is Pemphigus Vulgaris?
- most common type of Pemphigus (80% of cases)
- blistering occurs in the suprabasal layer
- affects the mucosa and skin of scalp, face, axilla, groin, trunk, and areas of pressure
47
what are the clinical features of Pemphigus Vulgaris?
lesions are vesicles and bullae that rupture easily leaving shallow erosions covered with dried serum and crust
48
what is the mechanism that causes Pemphigus Vulgaris?
Autoantibodies target desmogleins (3)—components of desmosomes responsible for cell adhesion which leads to loss of cohesion between keratinocytes, resulting in blisters and erosions
49
what are the microscopic findings of Pemphigus Vulgaris?
- netlike pattern of IgG deposits around cells (intercellular)
***This is a classic sign of desmoglein autoantibodies
50
What is Bullous Pemphigoid?
- autoimmune blistering disorder
- blisters forming in the subepidermal layer
- more common in the elderly
- typically affects the inner thighs, flexor surfaces of forearms, axilla, groin, and lower abdomen
51
what are the clinical features of Bullous Pemphigoid?
- lesions are typically tense bullae filled with clear fluid over erythematous skin
- blisters are 2 cm in diameter, and do not rupture easily
- heals without scarring if there is no secondary infection
52
what is the mechanism that causes Bullous Pemphigoid?
Autoantibodies target BPAG1 and BPAG2, proteins in the basal cell-basement membrane attachments (hemidesmosomes) which causes subepidermal blistering without acantholysis
53
what are the microscopic findings of Bullous Pemphigoid?
- Subepidermal Nonacantholytic Blister: epidermis intact.
- Eosinophils are present within the blister cavity
- Perivascular infiltrate contains lymphocytes, eosinophils, and neutrophils
- Linear deposition of IgG and complement (C3) along the dermoepidermal junction in a characteristic ribbon-candy pattern
***** differentiates bullous pemphigoid from pemphigus, which has a netlike pattern
54
what is Panniculitis and what are the two types?
An inflammatory condition that affects the subcutaneous tissue (fat layer) of the skin catagorized based on location of inflammation:
- Septal Panniculitis: Involves the connective tissue septa between fat lobules
- Lobular Panniculitis: Directly affects the fat lobules themselves
55
what is Erythema Nodosum?
a septal panniculitis (most common Panniculitis) usually associated with
- Infections: Streptococcus, tuberculosis, histoplasmosis, leprosy
- Medications: Sulfonamides, oral contraceptives
- Systemic Diseases: Sarcoidosis, inflammatory bowel disease, certain malignancies
56
what are the clinical features of Erythema Nodosum?
- Poorly defined, tender, erythematous plaques and nodules.
- Symmetrical distribution, mainly on lower legs
- Often associated with systemic symptoms like fever and malaise
57
what are the microscopic findings of Erythema Nodosum?
Widening of connective tissue septa due to:
- Edema, fibrin, and neutrophils
- Lymphocytes, histiocytes, giant cells, and occasional eosinophils
- Septal fibrosis without vasculitis
58
what are Verrucae (Warts)?
Benign growths of the skin and mucous membranes common in children and adolescents caused by Human Papillomavirus (HPV)
- typically self-limited, regressing in 6 months to 2 years
59
what is Verruca Vulgaris?
Most common form of Verrucae mainly on hands and periungual areas with warts appearing as tan, dome-shaped, rough-surfaced papules
60
what are the microscopic findings of Verrucae?
Epidermal Hyperplasia with
- Koilocytosis: Viral cytopathic effect causing cytoplasmic vacuolization and pale halos around nuclei
- Coarse keratohyaline granules
61
what is Molluscum Contagiosum?
Poxvirus infection causing umbilicated papules on the skin, is common in children and spreads through contact
62
what are the clinical features of Molluscum Contagiosum?
- Papules with a central umbilication
- Eosinophilic cytoplasmic inclusions called Henderson-Patterson bodies in the epidermis
63
what is Impetigo?
A highly contagious superficial skin infection caused by bacteria Staphylococcus aureus or Streptococcus pyogenes (beta-hemolytic)
64
what are the clinical features of Impetigo?
- Erythematous macules → evolve into small pustules that rupture and form honey-colored crusts.
- Commonly affects the face and hands.
65
what are Superficial Fungal Infections?
Fungal infections caused by dermatophytes limited to the stratum corneum of the epidermis
66
what is Tinea Capitis?
a type of superficial fungal infection affecting mainly children, that forms asymptomatic hairless patches, or erythema, crust formation and scales
67
what is Tinea Barbae?
a type of superficial fungal infection that infects beard skin of adult men
68
what is Tinea Corporis?
a common type of superficial fungal infection that infects any body surface, all ages and people predisposed to heat and humidity and lesions that are expanding round erythematous plaques with elevated scaly borders
69
what are the microscopic features of Tinea Corporis?
- mild eczematous (spongiotic) dermatitis and focal neutrophilic nabscesses
- deep red hyphae within the stratum corneum
70
what is Tinea Pedis (Athlete's Foot)?
a type of superficial fungal infection that affects feet, especially the web spaces with erythema and scaling and can lead to onychomycosis (nail infection)
71
what is Tinea Versicolor?
a type of superficial fungal infection of the upper trunk caused by Malassezia furfur (yeast) and causes tan-brown to white patches with fine scales
72
what are the microscopic findings for Tinea Versicolor?
- Spores and short, stubby pseudohyphae are present in the hyperkeratotic stratum corneum
- Many fungal organisms are seen on the PAS-D stain (“spaghetti and meatballs”)
