Musculoskeletal, Skin, and Connective Tissue - Pathology (2) Flashcards Preview

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Flashcards in Musculoskeletal, Skin, and Connective Tissue - Pathology (2) Deck (24):
1

Scleroderma (systemic sclerosis)

  • Definition
  • Findings
  • 2 major types:
    • Diffuse scleroderma
    • Limited scleroderma

  • Definition
    • Excessive fibrosis and collagen deposition throughout the body.
  • Findings
    • Commonly sclerosis of skin, manifesting as puffy and taut skin [A] [B] with absence of wrinkles.
    • Also sclerosis of renal, pulmonary (most common cause of death), cardiovascular, and GI systems.
    • 75% female.
  • 2 major types:
    • Diffuse scleroderma
      • Widespread skin involvement, rapid progression, early visceral involvement.
      • Associated with anti-Scl-70 antibody (anti-DNA topoisomerase I antibody).
    • Limited scleroderma
      • Limited skin involvement confined to fingers and face.
      • Also with CREST involvement: Calcinosis, Raynaud phenomenon, Esophageal dysmotility, Sclerodactyly, and Telangiectasia.
      • More benign clinical course. 
      • Associated with antiCentromere antibody (C for CREST).

2

Dermatologic macroscopic terms (morphology)

  • For each
    • Characteristics
    • Examples
  • Macule
  • Patch
  • Papule
  • Plaque
  • Vesicle

  • Macule [A]
    • C: Flat lesion with well-circumscribed change in skin color < 1 cm
    • Ex: Freckle, labial macule 
  • Patch [B]
    • C: Macule > 1 cm
    • Ex: Large birthmark (congenital nevus) 
  • Papule [C]
    • C: Elevated solid skin lesion < 1 cm
    • Ex: Mole (nevus), acne
  • Plaque [D]
    • C: Papule > 1 cm
    • Ex: Psoriasis 
  • Vesicle [E]
    • C: Small fluid-containing blister < 1 cm
    • Ex: Chickenpox (varicella), shingles (zoster) 

3

Dermatologic macroscopic terms (morphology)

  • For each
    • Characteristics
    • Examples
  • Bulla
  • Pustule
  • Wheal
  • Scale
  • Crust

  • Bulla [F]
    • C: Large fluid-containing blister > 1 cm
    • Ex: Bullous pemphigoid 
  • Pustule [G]
    • C: Vesicle containing pus
    • Ex: Pustular psoriasis 
  • Wheal [H]
    • C: Transient smooth papule or plaque
    • Ex: Hives (urticaria) 
  • Scale [I]
    • C: Flaking off of stratum corneum
    • Ex: Eczema, psoriasis, SCC 
  • Crust [J]
    • C: Dry exudate
    • Ex: Impetigo 

4

Dermatologic microscopic terms

  • For each
    • Characteristics
    • Examples
  • Hyperkeratosis
  • Parakeratosis
  • Spongiosis
  • Acantholysis
  • Acanthosis

  • Hyperkeratosis
    • C: Increased thickness of stratum corneum
    • Ex: Psoriasis, calluses
  • Parakeratosis
    • C: Hyperkeratosis with retention of nuclei in stratum corneum
    • Ex: Psoriasis 
  • Spongiosis
    • C: Epidermal accumulation of edematous fluid in intercellular spaces
    • Ex: Eczematous dermatitis
  • Acantholysis
    • C: Separation of epidermal cells
    • Ex: Pemphigus vulgaris
  • Acanthosis
    • C: Epidermal hyperplasia (increased spinosum)
    • Ex: Acanthosis nigricans

5

Pigmented skin disorders

  • Albinism
  • Melasma (chloasma)
  • Vitiligo

  • Albinism
    • Normal melanocyte number with decreased melanin production [A] due to decreased tyrosinase activity or defective tyrosine transport.
    • Can also be caused by failure of neural crest cell migration during development. 
    • Increased risk of skin cancer.
  • Melasma (chloasma)
    • Hyperpigmentation associated with pregnancy (“mask of pregnancy” [B]) or OCP use.
  • Vitiligo
    • Irregular areas of complete depigmentation [C].
    • Caused by autoimmune destruction of melanocytes.

6

Common skin disorders

  • Verrucae
  • Melanocytic nevus
  • Urticaria

  • Verrucae
    • Warts
    • Caused by HPV.
    • Soft, tan-colored, cauliflower-like papules [A].
    • Epidermal hyperplasia, hyperkeratosis, koilocytosis.
    • Condyloma acuminatum on genitals [B].
  • Melanocytic nevus
    • Common mole.
    • Benign, but melanoma can arise in congenital or atypical moles.
    • Intradermal nevi are papular [C].
    • Junctional nevi are flat macules [D].
  • Urticaria
    • Hives.
    • Pruritic wheals that form after mast cell degranulation [E].
    • Characterized by superficial dermal edema and lymphatic channel dilation.

7

Common skin disorders

  • Ephelis
  • Atopic dermatitis (eczema)
  • Allergic contact dermatitis

  • Ephelis
    • Freckle.
    • Normal number of melanocytes, increased melanin pigment [F].
  • Atopic dermatitis (eczema)
    • Pruritic eruption, commonly on skin flexures.
    • Often associated with other atopic diseases (asthma, allergic rhinitis).
    • Usually starts on the face in infancy [G] and often appears in the antecubital fossae [H] thereafter.
  • Allergic contact dermatitis
    • Type IV hypersensitivity reaction that follows exposure to allergen.
    • Lesions occur at site of contact (e.g., nickel [I], poison ivy, neomycin [J]).

8

Common skin disorders

  • Psoriasis
  • Seborrheic keratosis

  • Psoriasis
    • Papules and plaques with silvery scaling [K], especially on knees and elbows.
    • Acanthosis with parakeratotic scaling (nuclei still in stratum corneum). 
    • Increased stratum spinosum, decreased stratum granulosum.
    • Auspitz sign (arrow in [L])—pinpoint bleeding spots from exposure of dermal papillae when scales are scraped off.
    • Can be associated with nail pitting and psoriatic arthritis.
  • Seborrheic keratosis
    • Flat, greasy, pigmented squamous epithelial proliferation with keratin-filled cysts (horn cysts) [M].
    • Looks “stuck on” [N] [O].
    • Lesions occur on head, trunk, and extremities.
    • Common benign neoplasm of older persons.
    • Leser-Trélat sign—sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy (e.g., GI, lymphoid).

9

Infectious skin disorders

  • Impetigo
  • Cellulitis
  • Necrotizing fasciitis

  • Impetigo
    • Very superficial skin infection.
    • Usually from S. aureus or S. pyogenes.
    • Highly contagious.
    • Honey-colored crusting [A].
    • Bullous impetigo [B] has bullae and is usually caused by S. aureus.
  • Cellulitis
    • Acute, painful, spreading infection of dermis and subcutaneous tissues.
    • Usually from S. pyogenes or S. aureus.
    • Often starts with a break in skin from trauma or another infection [C].
  • Necrotizing fasciitis
    • Deeper tissue injury, usually from anaerobic bacteria or S. pyogenes.
    • Results in crepitus from methane and CO2 production.
    • “Flesh-eating bacteria.”
    • Causes bullae and a purple color to the skin [D].

10

Infectious skin disorders

  • Staphylococcal scalded skin syndrome
  • Hairy leukoplakia

  • Staphylococcal scalded skin syndrome
    • Exotoxin destroys keratinocyte attachments in the stratum granulosum only (vs. toxic epidermal necrolysis, which destroys the epidermal-dermal junction).
    • Characterized by fever and generalized erythematous rash with sloughing of the upper layers of the epidermis that heals completely.
    • Seen in newborns and children [E].
  • Hairy leukoplakia
    • White, painless plaques on the tongue that cannot be scraped off [F].
    • EBV mediated.
    • Occurs in HIV‑positive patients.

11

Pemphigus vulgaris

  • Type of disorder
  • Definition
  • Findings

  • Type of disorder
    • Blistering skin disorder
  • Definition
    • Potentially fatal autoimmune skin disorder with IgG antibody against desmoglein (component of desmosomes).
  • Findings
    • Flaccid intraepidermal bullae [A] caused by acantholysis (keratinocytes in stratum spinosum are connected by desmosomes)
      • Oral mucosa also involved.
    • Immunofluorescence reveals antibodies around epidermal cells in a reticular (net-like) pattern [B].
    • Nikolsky sign (+) (separation of epidermis upon manual stroking of skin).

12

Bullous pemphigoid

  • Type of disorder
  • Definition
  • Findings

  • Type of disorder
    • Blistering skin disorder
  • Definition
    • Less severe than pemphigus vulgaris.
    • Involves IgG antibody against hemidesmosomes
      • Epidermal basement membrane
      • Antibodies are “bullow” the epidermis.
  • Findings
    • Tense blisters [C] containing eosinophils affect skin but spare oral mucosa.
    • Immunofluorescence reveals linear pattern at epidermal-dermal junction [D].
    • Nikolsky sign (-).

13

Dermatitis herpetiformis

  • Type of disorder
  • Findings

  • Type of disorder
    • Blistering skin disorder
  • Findings
    • Associated with celiac disease.
    • Pruritic papules, vesicles, and bullae (often found on elbows) [E].
    • Deposits of IgA at the tips of dermal papillae.

14

Erythema multiforme

  • Type of disorder
  • Associations
  • Presentation

  • Type of disorder
    • Blistering skin disorder
  • Associated with...
    • Infections (e.g., Mycoplasma pneumoniae, HSV)
    • Drugs (e.g., sulfa drugs, β-lactams, phenytoin)
    • Cancers
    • Autoimmune disease.
  • Presents with multiple types of lesions
    • Macules, papules, vesicles, and target lesions (look like targets with multiple rings and a dusky center showing epithelial disruption) [F].

15

Stevens-Johnson syndrome

  • Type of disorder
  • Definition
  • Findings

  • Type of disorder
    • Blistering skin disorder
  • Definition
    • A more severe form of Stevens-Johnson syndrome with > 30% of the body surface area involved is toxic epidermal necrolysis [H] [I].
    • Usually associated with adverse drug reaction.
  • Findings
    • Characterized by fever, bulla formation and necrosis, sloughing of skin, and a high mortality rate.
    • Typically 2 mucous membranes are involved [G], and skin lesions may appear like targets as seen in erythema multiforme. 

16

Acanthosis nigricans

  • Definition
  • Associations

  • Definition
    • Epidermal hyperplasia causing symmetrical, hyperpigmented, velvety thickening of skin, especially on neck or in axilla [A].
  • Associated with...
    • Hyperinsulinemia (e.g., diabetes, obesity, Cushing syndrome)
    • Visceral malignancy (e.g., gastric adenocarcinoma).

17

Actinic keratosis

  • Definition
  • Findings

  • Definition
    • Premalignant lesions caused by sun exposure.
    • Risk of squamous cell carcinoma is proportional to degree of epithelial dysplasia.
  • Findings
    • Small, rough, erythematous or brownish papules or plaques [B].

18

Erythema nodosum

  • Definition
  • Associations

  • Definition
    • Painful inflammatory lesions of subcutaneous fat, usually on anterior shins.
  • Associations
    • Often idiopathic, but can be associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, streptococcal infections, leprosy, and Crohn disease [C].

19

Lichen Planus

  • Definition
  • Findings

  • Definition
    • Sawtooth infiltrate of lymphocytes at dermal-epidermal junction.
    • Associated with hepatitis C.
  • Findings
    • 6 P's of lichen PlanusPruritic, Purple, Polygonal Planar Papules and Plaques [D]
    • Mucosal involvement manifests as Wickham striae (reticular white lines).

20

Pityriasis rosea

  • “Herald patch” followed days later by “Christmas tree” distribution [E].
  • Multiple plaques with collarette scale.
  • Self-resolving in 6–8 weeks.

21

Sunburn

  • Definition
  • Findings
  • UVA vs. UVB

  • Definition
    • Acute cutaneous inflammatory reaction due to excessive UV irradiation.
  • Findings
    • Causes DNA mutations, inducing apoptosis of keratinocytes.
    • Can lead to impetigo [F] and skin cancers (basal cell carcinoma, squamous cell carcinoma, and melanoma).
  • UVA vs. UVB
    • UVA is dominant in tanning and photoaging
    • UVB is dominant in sunburn.

22

Basal cell carcinoma (438)

  • Definition
  • Findings

  • Definition
    • Most common skin cancer.
    • Found in sun-exposed areas of body.
    • Locally invasive, but almost never metastasizes.
  • Findings
    • Pink, pearly nodules, commonly with telangiectasias, rolled borders, and central crusting or ulceration [A].
    • BCCs also appear as nonhealing ulcers with infiltrating growth [B] or as a scaling plaque (superficial BCC) [C].
    • Basal cell tumors have “palisading” nuclei [D].

23

Squamous cell carcinoma (438)

  • Definition
  • Findings
  • Actinic keratosis
  • Keratoacanthoma 

  • Definition
    • Second most common skin cancer.
    • Associated with excessive exposure to sunlight, immunosuppression, and occasionally arsenic exposure.
    • Locally invasive, but may spread to lymph nodes and will rarely metastasize.
    • Associated with chronic draining sinuses.
  • Findings
    • Commonly appears on face [E], lower lip [F], ears, and hands.
    • Ulcerative red lesions with frequent scale.
    • Histopathology: keratin “pearls” [G].
  • Actinic keratosis
    • A scaly plaque
    • A precursor to squamous cell carcinoma.
  • Keratoacanthoma
    • A variant that grows rapidly (4–6 weeks)
    • May regress spontaneously over months [H].

24

Melanoma (438)

  • Definition
  • Findings
  • Treatment

  • Definition
    • Common tumor with significant risk of metastasis.
    • S-100 tumor marker.
    • Depth of tumor correlates with risk of metastasis.
    • Associated with sunlight exposure; fair-skinned persons are at increased risk.
    • At least 4 different types of melanoma [I] [J] [K] [L].
    • Often driven by activating mutation in BRAF kinase.
  • Findings
    • Look for the ABCDEs: Asymmetry, Border irregularity, Color variation, Diameter > 6 mm, and Evolution over time.
  • Treatment
    • Primary treatment is excision with appropriately wide margins.
    • Metastatic or unresectable melanoma in patients with BRAF V600E mutation may benefit from vemurafenib, a BRAF kinase inhibitor.

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