Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA Skin and SubQ Basic Science 4/6/10 Dr. Bennett Fontenot MD, PhD, JD, RN, RD, DMD, DDS, NP, BS, esq, PA

Anatomy Epidermis Keratinocytes Melanocytes Langerhans' cells stratum germinatum (basal), spinosum, granulosum, lucidum, corneum. Lose mitotic ability – 40-56 days Melanocytes derived from precursor cells of the neural crest extend dendritic processes upward from basal cell pigment is packaged into melanosomes and transported into the epidermis via dendritic processes, phagocytized by keritinocyes Despite 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' cells act as the skin's macrophages. Express class II MHC antigens, and has antigen-presenting capabilities

Anatomy Dermis Collagen- constitutes 70% of dermal dry weight and is responsible for its tensile strength. the skin primarily contains type I collagen Fetal dermis and new wounds contains mostly type III (reticulin fibers) collagen Elastic fibers Glycosaminoglycans complexes Cutaneous sensation Meissner's, Ruffini's, and Pacini's corpuscles transmit information on local pressure, vibration, and touch

Anatomy Three main adnexal structures: eccrine glands- sweat-producing eccrine glands are located over the entire body pilosebaceous units Hair folicles and sebaceous glands reservoir of pluripotential stem cells critical in epidermal reproductivity In skin graft harvest, residual hair follicles supply new keratinocytes to regenerate the epidermis and restore skin integrity apocrine glands primarily found in the axillae and anogenital region predispose both regions to suppurative hydroadenitis

Injuries Traumatic Caustic Dog Bites- Pasteurella multocida – Augmentin Human Bites- Eikenella corrodens Dirty- allow to heal by secondary intention after debridement and irrigation Caustic Acid: coagulative injury copious skin irrigation for at least 30 minutes with water hydrofluoric acid - neutralized with calcium, Alkaline agents liquefactive injury - a longer, more sustained period of injury iirrigation of the affected area with continuous water flow should be maintained for at least 2 hours

Infections/Inflammatory Diseases

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 abscess Carbuncle- more involved, deep-seated infections that result in multiple draining cutaneous sinuses are called carbuncles. Furuncle/Carbuncle require I&D +/- ABX

Infections/Inflammatory Diseases

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 organisms Group A streptococci, Clostridium species Gram-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.

Infections/Inflammatory Diseases

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 sinuses Treatment Acute 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

Benign Tumors Cysts Epidermal 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 midline Trichilemmal (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 keratin If infected- tx with I&D, must remove all of cyst wall to prevent recurrence Acrochordons, Dermatofibromas, Lipomas

MALIGNANT TUMORS Basal Cell Carcinoma the most common type of skin cancer Waxy and cream colored, present with rolled, pearly borders surrounding a central ulcer. Slow growing, and metastasis is extremely rare Extensive local tissue destruction is common Treament: 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

MALIGNANT TUMORS Squamous Cell Carcinoma Arise from epidermal keratinocytes increased 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 Queyrat Lesions arising in burn scars (Marjolin's ulcer), areas of chronic osteomyelitis, and areas of previous injury metastasize early Treament: Surgical excision with 1-cm margins. Tumors located on the cheek, nose, or lip, may be approached with Mohs' surgery The need for lymph node (LN) dissection remains a topic of debate. Regional LN excision is indicated for clinically palpable nodes lesions 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.

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 manifestations congenital hypertrophy retinal pigment epithelium epidermoid cysts, and osteomas. Also at risk for upper 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

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 age Lynch 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

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 characteristic Nodular type accounts for 15 to 30% of melanomas. lack of radial growth; all are in the vertical growth phase at diagnosis. Lentigo maligna accounts for 4 to 15% of melanomas, most frequently on the neck, face, and hands of the best prognosis because invasive growth occurs late. Acral lentiginous least common subtype, and constitutes only 2 to 8% 29 to 72% of all melanomas in dark-skinned people on the palms, soles, and subungual regions.

Prognosis Prognosis is based on Depth of Invasion Presence of ulceration confers a worse prognosis for same depth of invasion Nodular 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

Breslow Thickness

Diagnosis Requires excisional biopsy or incisional Bx

Nodes

Nodes All 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.

Mets Once melanoma has spread to a distant site, median survival is 7 to 8 months 5-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