Introduction + Skin lesions Flashcards
Gross structure of the skin
Epidermis
Dermis
Hypodermis/ Subcutis
Structure of epidermis
Corneal layer - anuclear keratinocytes
Clear layer - only thick skin
Granular layer - keratinocytes with granules
Spinous layer - keratinocytes with spine like projections
Basal layer - stem cells
Cells of epidermis
Melanocytes - in the basal layer, produce melanin
Keratinocytes - throughout epidermis, store melanin
Merkel cells - mechanoreceptors, basal layer
Langerhans cells - dendritic cells, basal and spinous layer
Structure of dermis
Papillary layer - loose CT, Meissner corpuscles
Reticular layer - dense CT, Pacinians corpuscles, sebaceous glands, hair follicles, sweat glands, blood vessels
Structure of hypodermis/subcutis
Adipocytes, blood vessels, nerves
Anatomy of nail
- cornified plate - compact, smooth, transparent, colorless
- translucent nail bed vessels = pink color
- matrix onychoblasts - determined nail growth
Anatomy of hair
- Hair bulb
- Root sheath
- Hair shaft
Sebaceous glands are located throughout the skin, EXCEPT:
Palms and soles
Eccrine vs. Apocrine sweat glands
Eccrine - functioning from birth, all over the body (most common in palms, soles and forehead)
- ducts open in pore at skin’s surface
- “watery sweat”
Apocrine - functioning from puberty, most common in armpit and anogenital region
- ducts open into hair follicles
- “fatty sweat”
- odorless but when decomposed by bacteria on skin a “body odor” is created
Macule
- flat, circumscribed, non-palpable
- just a change of color
- Macule - <1cm
- Patch - >1cm
Types of Macula
- Vascular
- damaged vessels, if you pinch it - it disappears
- Roseola (viruses, allergy, medication),
- Erythema (hand-size)
- Erythroderma (redness ALL over the body) - Hemorrhagic
- if you pinch it - it doesn’t disappear
- Petechia - most common causes: vomiting, vasculitis, viral infections
- Ecchymosis
- Suggillation - Pigmented
- white - ex: vitiligo
- hypopigmented - leukoderma (fungi, scarring, syphillis)
- hyperpigmented - congenital (freckles, nevi) or acquired (UV rays, aging)
Papule
- elevated, solid, palpable lesions
- <1cm
- causes: epidermal cell proliferation, dermal cell proliferation, accumulation of metabolic products in dermis
- warts, psoriasis, molluscum contagiosum, lichen planus, acne, nevus, xantomas
Plaque
- circumscribed, palpable lesion
- > 1cm
- may result from convalescence of papules
Nodules
- elevated, solid, palpable
- > 1cm
- primarily in dermis and subcutis
- keratoacanthoma, basal cell carcinoma, skin sarcoidosis, acne, gout
Wheel (urticaria)
- transient elevation due to edema
- pale center, erythematous ring
- smooth surface
- itchy dermal skin swelling
-if urticaria last for more than 24h –> biopsy to exclude vasculitis urticaria