Musculoskeletal, Skin, and Connective Tissue- Dermatology and pharmacology Flashcards
Skin layers
epidermis, dermis, subcutaneous fat
Epidermis layers: Basale, Spinosum, Granulosum, Lucidum, Corneum
Epithelial cell junctions
- Tight junction
- Adherens junction
(zonula occludens)- composed of claudins and occludins.
(belt desmosome, zonula adherens)— forms “belt” connecting actin cytoskeletons of adjacent cells with CADherins. Loss of E-cadherin promotes metastasis
Epithelial cell junctions
- Desmosome
- Gap junction
- Hemidesmosome
(macula adherens)—structural support via intermediate filament interactions. Autoantibodies to desmoglein pemphigus vulgaris.
channel proteins called connexons permit electrical and chemical communication between cells.
Connects keratin in basal cells to underlying basement membrane. Autoantibodies bullous pemphigoid.
Dermatologic macroscopic terms
Pag. 462
Dermatologic microscopic terms
- Hyperkeratosis
- Parakeratosis
- Hypergranulosis
- Spongiosis
- Acantholysis
- Acanthosis
thickness of stratum corneum (psoriasis)
Retention of nuclei in stratum corneum (psoriasis)
thickness of stratum granulosum (liquen planus)
Epidermal accumulation of edematous fluid in intercellular spaces (Eczematous dermatitis)
Separation of epidermal cells (Pemphigus vulgaris)
Epidermal hyperplasia (Increase spinosum) (Acanthosis nigricans)
Pigmented skin disorders
- Albinism
Normal melanocyte number with decrease melanin production due to low tyrosinase activity or defective
tyrosine transport. risk of skin cancer.
Pigmented skin disorders
- Melasma (chloasma)
Hyperpigmentation associated with pregnancy (“mask of pregnancy”) or OCP use.
Pigmented skin disorders
- Vitiligo
Irregular patches of complete depigmentation. Caused by autoimmune destruction of melanocytes.
Seborrheic dermatitis
Erythematous, well-demarcated plaques with greasy yellow scales in areas rich in sebaceous glands, such as scalp, face, and periocular region.
Common in both infants and adults, associated with Parkinson disease.
Possibly associated with Malassezia spp. Treat with topical antifungals and corticosteroids.
Acne
- Etiology
- Treatment
Multifactorial etiology— sebum/androgen production, abnormal keratinocyte desquamation, Cutibacterium acnes colonization, and inflammation.
Treatment includes retinoids, benzoyl peroxide, and antibiotics
Atopic dermatitis (eczema)
Pruritic eruption, commonly on skin flexures. Often appears on face in infancy and then in antecubital fossa in children and adults.
Associated with other atopic diseases.
Mutations in filaggrin gene predispose.
Allergic contact dermatitis
Type IV hypersensitivity reaction that follows exposure to allergen. Lesions occur at site of contact (eg, nickel, poison ivy, neomycin).
Melanocytic nevus
Common mole. Benign, but melanoma can arise in congenital or atypical moles. Intradermal nevi are papular. Junctional nevi are flat macules.
Pseudofolliculitis barbae
firm, hyperpigmented papules and pustules that are painful and pruritic. Located on cheeks, jawline, and neck.
Commonly occurs as a result of shavin
Psoriasis
Papules and plaques with silvery scaling, especially on knees and elbows. Acanthosis with parakeratotic scalin. Munro microabscesses. Auspitz sign
Associated with nail pitting and psoriatic arthritis.
Rosacea
Inflammatory facial skin disorder characterized by erythematous papules and pustules.
May be associated with facial flushing in response to external stimuli (eg, alcohol, heat).
Phymatous rosacea can cause rhinophyma (bulbous deformation of nose).
Seborrheic keratosis
Flat, greasy, pigmented squamous epithelial proliferation with keratin-filled cysts (horn cysts). Looks “stuck on.”
Leser-Trélat sign
Sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy (eg, GI, lymphoid).
Verrucae
Warts; caused by low-risk HPV strains. Soft, tan-colored, cauliflower-like papules. Condyloma acuminatum on anus or genitals
Urticaria
Hives. Pruritic wheals that form after mast cell degranulation.
Characterized by superficial dermal edema and lymphatic channel dilation
Vascular tumors of skin
- Angiosarcoma
Blood vessel malignancy typically occurring in the head, neck, and breast areas. Usually in elderly, on sun-exposed areas.
Associated with radiation therapy and chronic postmastectomy lymphedema.
Hepatic angiosarcoma associated with vinyl chloride and arsenic exposures.
Vascular tumors of skin
- Bacillary angiomatosis
Benign capillary skin papules found in AIDS patients. Caused by Bartonella infections.
Mistaken for Kaposi sarcoma, but has neutrophilic infiltrate.
Vascular tumors of skin
- Cherry hemangioma
- Cystic hygroma
Benign capillary hemangioma of the elderly
Cavernous lymphangioma of the neck. Associated with Turner syndrome
Vascular tumors of skin
- Kaposi
Endothelial malignancy most commonly of the skin, but also mouth, GI tract, and respiratory tract.
Associated with HHV-8 and HIV
*Has lymphocitic infiltrate
Vascular tumors of skin
- Pyogenic granuloma
Polypoid lobulated capillary hemangioma that can ulcerate and bleed.
Associated with trauma and pregnancy
Vascular tumors of skin
- Strawberry hemangioma
Benign capillary hemangioma of infancy. Appears in first few weeks of life (1/200 births); grows rapidly and regresses spontaneously by 5–8 years old.
Skin infections (Pag. 466) - Bacterial infections
Impetigo Erysipelas Cellulitis Abscess Necrotizing fasciitis Staphylococcal scalded skin syndrome
Skin infections (Pag. 466) - Viral infections
Herpes
Molluscum contagiosum
Varicella zoster virus
Hairy leukoplakia
Blistering skin disorders
- Pemphigus vulgaris
IgG antibody against desmoglein.
Flaccid intraepidermal bullae caused by acantholysis. oral mucosa is also involved. Type II hypersensitivity
Immunofluorescence reveals antibodies around epidermal cells in a reticular (net-like) pattern. Nikolsky sign ⊕.
Blistering skin disorders
- Bullous pemphigoid
Less severe than pemphigus vulgaris. Type II hypersensitivity: involves IgG antibody against hemidesmosomes.
Immunofluorescence reveals linear pattern at epidermal-dermal junction. Nikolsky sign ⊝.
Blistering skin disorders
- Dermatitis herpetiformis
Pruritic papules, vesicles, and bullae (on elbows). Deposits of IgA at tips of dermal papillae.
Associated with celiac disease.
Treatment: dapsone, gluten-free diet.
Blistering skin disorders
- Erythema multiforme
Associated with infections (eg, Mycoplasma pneumoniae, HSV), drugs (eg, sulfa drugs, β-lactams,
phenytoin), cancers, autoimmune disease.
Multiple types of lesions—macules, papules, vesicles, target lesions.
Blistering skin disorders
- Stevens-Johnson syndrome
Fever, bullae formation and necrosis, sloughing of skin at dermal-epidermal junction, high mortality rate. Typically 2 mucous membranes are involved.
Usually associated with adverse drug reaction.
> 30% of the body surface area involved is toxic epidermal necrolysis (TEN). 10–30% involvement denotes SJS-TEN.
Burn classifications
- 1st degree
- 2nd degree
- 3rd degre
Superficial, through epidermis
Through epidermis and dermis. Skin is blistered and usually heals without scarring.
Epidermis, dermis, and hypodermis. Skin scars with wound healing. *Painless
Actinic keratosis
Premalignant lesions caused by sun exposure.
Small, rough, erythematous or brownish papules or
plaques.
Risk of squamous cell carcinoma is proportional to degree of epithelial dysplasia.
Erythema nodosum
Painful, raised inflammatory lesions of subcutaneous fat, usually on anterior shins.
Often idiopathic, but can be associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, streptococcal infections, leprosy, inflammatory bowel disease
Lichen Planus
6 P’s
Pruritic, Purple, Polygonal Planar Papules and Plaques
Mucosal involvement manifests as Wickham striae (reticular white lines) and hypergranulosis. Sawtooth infiltrate of lymphocytes at dermal-epidermal junction.
Associated with hepatitis C
Pityriasis rosea
“Herald patch” followed days later by other scaly erythematous plaques, often in a “Christmas tree” distribution on trunk.
Multiple pink plaques with collarette scale. Self-resolving in 6–8 weeks.
Basal cell carcinoma
Most common skin cancer. Found in sun-exposed areas. Locally invasive, but rarely metastasizes.
Waxy, pink, pearly nodules, commonly with telangiectasias, rolled borders, central crusting or ulceration.
BCCs also appear as nonhealing ulcers with infiltrating growth or as a scaling plaque (superficial BCC). Basal cell tumors have “palisading” nuclei.
Squamous cell carcinoma
Second most common skin cancer. Associated with excessive exposure to sunlight, immunosuppression, chronically draining sinuses, and occasionally arsenic exposure.
Ulcerative red lesions with frequent scale.
Histopathology: keratin “pearls”
Keratoacanthoma
is a variant of squamous cell carcinomathat grows rapidly (4–6 weeks) and may regress spontaneously over months.
Melanoma
- Marker
- Risk factors
- Scale for depht
Significant risk of metastasis. S-100 tumor marker.
Associated with sunlight exposure and dysplastic nevi.
Depth of tumor (Breslow thickness) correlates with risk of metastasis.
Melanoma
- Types
- Genetics
At least 4 different types: Superficial spreading Nodular Lentigo maligna Acral lentiginous
Often driven by activating mutation in BRAF kinase V6000E (vemurafenib)
Arachidonic acid pathway
Pag. 470
Teriparatide
- Mechanism
- Clinical use
- Adverse effects
Recombinant PTH analog. Increase osteoblastic activity when administered in pulsatile fashion.
Osteoporosis
Risk of osteosarcoma. Transient hypercalcemia
TNF-α inhibitors
Etanercept Infliximab, adalimumab, certolizumab, golimumab
Bisphosphonates
- names
- mecanism
Alendronate, ibandronate, risedronate, zoledronate.
Pyrophosphate analogs; bind hydroxyapatite in bone, inhibiting osteoclast activity.
Bisphosphonates
- clinical use
- adverse effects
Osteoporosis, hypercalcemia, Paget disease of bone, metastatic bone disease, osteogenesis imperfecta.
Esophagitis (if taken orally, patients are advised to take with water and remain upright for 30 minutes), osteonecrosis of jaw, atypical femoral stress fractures.
