1 Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA Skin and SubQBasic Science4/6/10Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA
2 Anatomy Epidermis Keratinocytes Melanocytes Langerhans' cells stratum germinatum (basal), spinosum, granulosum, lucidum, corneum.Lose mitotic ability – daysMelanocytesderived from precursor cells of the neural crestextend dendritic processes upward from basal cellpigment is packaged into melanosomes and transported into the epidermis via dendritic processes, phagocytized by keritinocyesDespite differences in skin tone, the density of melanocytes is constant among individuals.Rate of melanin production, transfer to keratinocytes, and melanosome degradation that determine the degree of skin pigmentation.Langerhans' cellsact as the skin's macrophages.Express class II MHC antigens, and has antigen-presenting capabilities
3 AnatomyDermisCollagen- constitutes 70% of dermal dry weight and is responsible for its tensile strength.the skin primarily contains type I collagenFetal dermis and new wounds contains mostly type III (reticulin fibers) collagenElastic fibersGlycosaminoglycans complexesCutaneous sensationMeissner's, Ruffini's, and Pacini's corpuscles transmit information on local pressure, vibration, and touch
4 Anatomy Three main adnexal structures: eccrine glands- sweat-producing eccrine glands are located over the entire bodypilosebaceous unitsHair folicles and sebaceous glandsreservoir of pluripotential stem cells critical in epidermal reproductivityIn skin graft harvest, residual hair follicles supply new keratinocytes to regenerate the epidermis and restore skin integrityapocrine glandsprimarily found in the axillae and anogenital regionpredispose both regions to suppurative hydroadenitis
5 Injuries Traumatic Caustic Dog Bites- Pasteurella multocida – AugmentinHuman Bites- Eikenella corrodensDirty- allow to heal by secondary intention after debridement and irrigationCausticAcid:coagulative injurycopious skin irrigation for at least 30 minutes with waterhydrofluoric acid - neutralized with calcium,Alkaline agentsliquefactive injury - a longer, more sustained period of injuryiirrigation of the affected area with continuous water flow should be maintained for at least 2 hours
7 Folliculitis, Furuncles, and Carbuncles Folliculitis is an infection of the hair follicle.Usually Staphylococcus, but gram-negative organisms may cause follicular inflammation as well.Furuncle (boil) begins as folliculitis, but may eventually progress to form a fluctuant abscessCarbuncle- more involved, deep-seated infections that result in multiple draining cutaneous sinuses are called carbuncles.Furuncle/Carbuncle require I&D +/- ABX
9 Necrotizing fasciitis The most common sites are the external genitalia, perineum, or abdominal wall (Fournier gangrene).Necrotizing fasciitis represents a rapid, extensive infection of the fascia deep to the adipose tissue, without involvement of muscle.Necrotizing myositis primarily involves the muscles but typically spreads to adjacent soft tissues.The most common organismsGroup A streptococci, Clostridium speciesGram-negative species- Escherichia coli, Enterobacter, Pseudomonas species,Clinical risk factors - diabetes mellitus, malnutrition, obesity, steroid use, renal failure, cirrhosis.Management - broad-spectrum IV antibiotics, aggressive surgical debridement.
11 Hidradenitis Suppurativa Defect of the terminal follicular epithelium.Apocrine gland blockage, obstructed infection leads to abscess formation throughout affected axillary, inguinal, and perianal regions.Foul-smelling sinusesTreatmentAcute infections- application of warm compresses, antibiotics, and open drainage.Chronic hidradenitis- wide excision is required and closure may be achieved via skin graft or local flap placement
12 Benign TumorsCystsEpidermal cysts- most common type, may present as a single, firm nodule anywhere on the body.Dermoid cysts- are congenital lesions that result when epithelium is trapped during fetal midlineTrichilemmal (pilar) cysts- most often on the scalp of females. When ruptured, these cysts have an intense, characteristic odor.Difficult to distinguish one type of cyst from another: Each cyst presents as a subcutaneous, thin-walled nodule containing keratinIf infected- tx with I&D, must remove all of cyst wall to prevent recurrenceAcrochordons, Dermatofibromas, Lipomas
13 MALIGNANT TUMORS Basal Cell Carcinoma the most common type of skin cancerWaxy and cream colored, present with rolled, pearly borders surrounding a central ulcer.Slow growing, and metastasis is extremely rareExtensive local tissue destruction is commonTreament:Surgical excision with 0.5-cm to 1-cm margins.Tumors located on the cheek, nose, or lip, may be best approached with Mohs' surgery
14 MALIGNANT TUMORS Squamous Cell Carcinoma Arise from epidermal keratinocytesincreased invasiveness and tendency to metastasize.Before local invasion, in situ SCC lesions are termed Bowen's disease.In situ SCC tumors specific to the penis are referred to as erythroplasia of QueyratLesions arising in burn scars (Marjolin's ulcer), areas of chronic osteomyelitis, and areas of previous injury metastasize earlyTreament:Surgical excision with 1-cm margins.Tumors located on the cheek, nose, or lip, may be approached with Mohs' surgeryThe need for lymph node (LN) dissection remains a topic of debate.Regional LN excision is indicated for clinically palpable nodeslesions arising in chronic wounds are more aggressive- prophylactic LN dissection is indicated.Metastatic disease is a poor prognostic sign, and only 13% of patients typically survive 10 years.
15 APC Gene and Familial Adenomatous Polyposis Hundreds to thousands of polyps in the colon and rectum. The polyps usually appear in adolescence and, if left untreated, progress to colorectal cancer.FAP is associated with benign extracolonic manifestationscongenital hypertrophyretinal pigment epitheliumepidermoid cysts, and osteomas.Also at risk forupper intestinal neoplasms (gastric and duodenal polyps, duodenal and periampullary cancer),hepatobiliary tumors (hepatoblastoma, pancreatic cancer, and cholangiocarcinoma),thyroid carcinomas, desmoid tumors, and medulloblastomas.Gardner’s and Turcot’s
16 Mismatch Repair Genes and Hereditary Nonpolyposis Colorectal Cancer (HNPCC) Autosomal dominant hereditary cancer syndrome that predisposes to a wide spectrum of cancers, including colorectal cancer without polyposis.HNPCC consists of at least two syndromes:Lynch syndrome 1- colorectal cancer with early ageLynch syndrome 2- colorectal cancer + carcinoma of the endometrium, transitional cell carcinoma of the ureter and renal pelvis, and carcinomas of the stomach, small bowel, ovary, and pancreas.Amsterdam Criteria
17 The Melanoma Superficial spreading, Nodular type Lentigo maligna Most common- accounts for up to 70% of melanomas.typically flat and measure 1 to 2 cm in diameter at diagnosis.Before vertical extension, a prolonged radial growth phase is characteristicNodular typeaccounts for 15 to 30% of melanomas.lack of radial growth; all are in the vertical growth phase at diagnosis.Lentigo malignaaccounts for 4 to 15% of melanomas,most frequently on the neck, face, and hands of thebest prognosis because invasive growth occurs late.Acral lentiginousleast common subtype, and constitutes only 2 to 8%29 to 72% of all melanomas in dark-skinned peopleon the palms, soles, and subungual regions.
18 Prognosis Prognosis is based on Depth of Invasion Presence of ulceration confers a worse prognosis for same depth of invasionNodular melanomas have the same prognosis as superficial spreading types when lesions are matched for depth of invasion.Lentigo maligna has a better prognosis even after correcting for thickness, and acral lentiginous has a worse prognosis
22 NodesAll microscopically or clinically positive LNs should be removed by regional nodal dissection.When groin LNs are removed, the deep (iliac) nodes must be removed along with the superficial (inguinal) nodes,For axillary dissections, the nodes medial to the pectoralis minor muscle also must be resected.For lesions on the face, anterior scalp, and ear, a superficial parotidectomy to remove parotid nodes and a modified neck dissection is recommended.
23 MetsOnce melanoma has spread to a distant site, median survival is 7 to 8 months5-year survival rate is less than 5%.Solitary lesions in the brain, GI tract, or skin that are symptomatic should be excised when possible.Use of radiation therapy, regional and systemic chemotherapy, and immunotherapy are all under investigation – interferon alpha