Chapter 18: Plastics, skin, and soft tissues. Flashcards
Skin: primarily cellular
Epidermis
Main cell type in epidermis; originate from basal layer; provide mechanical barrier
Keratinocytes
Neuroectodermal origin (neural crest cells); in basal cell layer of epidermis
Melanocytes
Have dendritic processes that transfer melanin to neighboring keratinocytes via melanosomes
Melanocytes
How do melanocytes differ among races?
Density of melanocytes is the same among races; difference is in melanin production
Skin: primarily structural proteins (collagen) for the epidermis
Dermis
- Acts as antigen-presenting cells (MHC Class II)
- Originate form bone marrow
- Have a role in contact hypersensitivity reactions (type 4)
Melanocytes
Sensory nerves: pressure
Pacinian corpuscles
Sensory nerves: warmth
Ruffini’s endings
Sensory nerves: cold
Krause’s end-bulbs
Sensory nerves: Meissner’s corpuscles
Tactile sense
Aqueous sweat (thermal regulation, usually hypotonic)
Eccrine sweat glands
Milky sweat
- highest concentration of glands in palms and soles
Apocrine sweat glands
What autonomic is in control of sweat production?
Most sweat is the result of sympathetic nervous system via acetylcholine
Drug type: increased skin absorption
Lipid-soluble drugs
Predominate collage type in skin; 70% of dermis; gives tensile strength
Type 1 Collagen
Resistance to stretching (collagen)
Tension
Ability to regain shape (branching proteins that can stretch to 2x normal length)
Elasticity
What causes Cushing’s striae?
Caused by loss of tensile strength and elasticity
MCC of pedicled or anastomosed free flap necrosis
Venous thrombosis
Flaps: what causes tissue expansion?
Occurs by local recruitment, thinning of the dermis and epidermis, mitosis
TRAM flaps: complications
Flap necrosis, ventral hernia, bleeding, infection, abdominal wall weakness
TRAM flaps: rely on what vessel?
Superior epigastric vessels
Most important determinant of TRAM flap viability?
Periumbilical perforators
What is a TRAM flap?
Transversus rectus abdominis flap
Stage I Pressure ulcer
Erythema and pain; no skin loss
Stage 2 Pressure Ulcer
- Treatment?
Partial skin loss with yellow debris
- Tx: local treatment, keep pressure off
Stage 3 Pressure Ulcer
- Treatment?
Full-thickness skin loss; subcutaneous fat exposure
- Tx: sharp debridement; likely need myocutaneous flap
Stage 4 Pressure Ulcer
- Treatment?
Involves bony cortex, muscle
- Tx: myocutaneous flap
- Damages DNA and repair mechanisms
- Both a promoter and initiator
UV radiation
Single best factor for protecting skin from UV radiation
Melanin
Responsible for chronic sun damage
UV-B
Represents only 5% of skin CA but accounts for 65% of the deaths
Melanoma
Risk factors for melanoma
- Dysplastic, atypical or large congenital nevi
- Familial BK mole syndrome
- Xeroderma pigmentosum
- Fair complexion, easy sunburn, intermittent sunburns, previous skin CA, previous XRT
10% lifetime risk for melanoma
Dysplastic, atypical, or large congenital nevi
Almost 100% risk of melanoma
Familial BK mole syndrome
% melanomas that are familial
10%
MC melanoma site on skin
Back in men, legs in women
What carries a worse prognosis in melanoma?
Men, ulcerated lesions, ocular and mucosal lesions
Signs of melanoma
- Asymmetry (angulations, indentation, notching, ulceration, bleeding)
- Borders that are irregular
- Color change (darkening)
- Diameter increase
- Evolving over time
Where does melanoma originate?
Originates from neural crest cells (melanocytes) in basal layer epidermis
Color: most ominous sign of melanoma
Blue color
MC location for distant melanoma metastases
Lung
Diagnosis melanoma:
- 2 cm lesion or cosmetically sensitive area
- 2cm or cosmetically sensitive area: incisional biopsy (or punch biopsy), will need to resect with margins if path shows melanoma
Five types of melanoma
- Melanoma in situ or thin lentigo maligna (Hutchinson’s freckle)
- Lentigo maligna melanoma
- Superficial spreading melanoma
- Nodular
- Acral lentiginous
Components of melanoma staging workup
Chest/abd/pelvic CT, LFTs, and LDH for all melanoma > 1mm; examine all possible draining lymph nodes
Melanoma: treatment for all stages
1) Resection of primary tumor with appropriate margins
- AND -
2) Management of lymph nodes
Surgical margins for melanoma excision:
- In situ (mm)
- 1.0 (mm)
- 1.1 - 2.0 (mm)
- > 2.0 (mm)
- In situ (mm): 0.5 - 1.0 cm
- 1.0 (mm): 1.0 cm
- 1.1 - 2.0 (mm): 1.0 - 2.0 cm
- > 2.0 (mm): 2.0 cm
Surgical margins for melanoma excision:
- In situ (mm)
- In situ (mm): 0.5 - 1.0 cm
Surgical margins for melanoma excision:
- 1.0 (mm)
- 1.0 (mm): 1.0 cm
Surgical margins for melanoma excision:
- 1.1 - 2.0 (mm)
- 1.1 - 2.0 (mm): 1.0 - 2.0 cm
Surgical margins for melanoma excision:
- > 2.0 (mm)
- > 2.0 (mm): 2.0 cm
Melanoma: what nodes do you need to resect?
Always need to resect clinically positive nodes
Melanoma: when do you perform sentinel lymph node biopsy?
If nodes clinically negative and tumor >/ 1 mm deep
Characteristic of involved nodes in melanoma
Involved nodes usually nontender, round, hard 1-2 cm
What do you need to include for all anterior head / neck melanomas >/ 1mm deep?
Superficial parotidectomy (20% metastasis rate to parotid)
Tx: axillary node melanoma with no other primary
Complete axillary node dissection (remove Level 1, 2 , and 3 nodes - unlike breast CA)