82.Skin dz Flashcards
% of histologically malignant skin tumors in dogs vs cats
20-40% M in dogs50-60% M in cats
what is the most important factor in local tumor control
surgical wound margin!1. intracapsular/intralesional (debulking or cytoreductive; leave macroscopic disease)2. marginal (often within pseudo capsule leaving microscopic disease behind)3. wide (removing some normal tissue)4. radical (an entire compartment is removed
4 surgical principles for tumor resection
- early ligation of large tumor vessels to minimize tumor cells entering circulation2. stay sutures, allis tissue forceps to avoid touching tumor3. change instruments/gloves if manipulating tumor4. copious lavage5. remove benign tumors first!
tissues most sensitive to chemotherapy and wound healing
intestinal tissues are most sensitivein general start chemo 7-10 days post surgeryneed more research
effects of radiation therapy on wound healing
dose-dependent injury to tissuestissue damage is more permanent than that of chemousually advised to start radiation therapy 1-3 weeks post op
4 types of radiation therapy injury to local tissues
- local erythema2. dry desquamation (superficial)3. moist desquamation (loss of basal layer of epidermis) 4. necrosis (dermal destruction/irreversible ulcer)
TNM staging system
T tumor size and invasiveness 0, 5 cm, invasionN node involvement 0, 1–ipsi, 2–contra or bilateral, 3–fixedM presence of distant mets 0–no, 1–yes
accuracy of FNA for diagnosing neoplasia
90%can be diagnosed cytologically but still need bx for tumor grade and confirmation of tumor origin
difference in spread of epithelial vs mesenchymal tumors
epithelial–lymphaticsmesenchymal–hematogenous
CT vs radiographs for detection of pulmonary nodules or mets
CT 1 mmradiographs 7-9 mm
2 main functions of the lymphatic system
- transport (lymph,lipids, fluid excess, cell debris/nutrients)2. immune response
eventually lymph enters systemic circulation via
thoracic duct
cortex and medulla of a lymph node
cortex: contains B cells arranged in follicles with germinal centers (Bcells and plasma cells) that is surrounded by rim of T cellsparacortex: t cells and APC (macros)medulla: cords of lymphocytes, macros, plasma cells; btwn cords are sinuses with discontinuous endothelium
how to determine a sentinel LN
blue dye or low dose radio nucleotide and gamma cameramany nodes may be draining tumor area so hard to know which to remove for staging purposes which may or may not be prognostic for the type of tumor in question (controversial)
potential benefits of lymphadenectomy
- possibly slow the rate of mets2. may reduce clinical signs of paraneoplastic syndrome or palliate symptoms3. tumor debulking to increase local control 4. staging of diseaseonly helpful if removing the lymph node draining tumor and multiple LN may be involved
causes of lymphadenitis
mycobacteriumbacteriafungiparasites–Brugia (filariasis)cytology, biopsy, culture
persistent inflammatory edema from poor lymph drainage can lead to what….
mesenchymal cell proliferation which may cause irreversible thickening of skin and subcutis
lymph edema physiology
occurs when interstitial P increases as a result of a fluid imbalance btwn capillary filtration and lymphatic return1. high lymphatic load2. decreased plasma oncotic P3. increased vascular permeability4. obstruction of lymph system
histologic findings in chronic lymphedema
- thicken BM of lymph vessels2. increase macros, fibroblasts3. increase amounts of collagenall of which may lead to fibrosis of SQ with chronic lymph edema
4 most common skin tumors in cats vs dogs
DOGSMCT, ST sarcoma, perianal adenoma, SCCCATSSCC, basal cell tumors, MCT, ST sarcoma
types of round cell tumors (6)
- lymphoma2. malignant histocytosis3. TVT4. MCT5. plasma cell tumors6. histocytomas
papilloma
BENIGNcauliflower likeassociated with DNA viral causetransmission can occur directly and indirectlymay resolve within 3 months excision or cryotherapy is size or location is causing a problem
SCC
most common skin neoplasm in catsmalignantsolar exposure– non pigmented skin is most commonly affected precursor –actinic keratosispapilloma virus relationship potential can be proliferative or erosiveassociated with mutation in p53 tumor suppressor gene
name of multi centric SCC in situ in cats
Bowenoid in situ carcinoma in cats (RARE)multifocal crusted plaques anywhere on body
most common location of SCC in dogs vs cats
dogs: subungual, digital, scrotum, legs, anuscats: pinnae, eyes, nose,
risk of white cats and SCC
white cats have a 13x higher risk compared to cats with other coat colors
MST of SCC following pinnectomy or nosectomy in cats
673 days
therapeutic options for SCC
- cryotherapy (small early lesions, multiple tx, no histo dx)2. plesiotherapy3. radiation therapy (not evaluated in conjunction w sx)4. photodynamic therapy5. chemotherapy (NOT as sole tx, intralesional possible6. immunomodulatory therapy (Imiquimod cream–75% develop new lesions)7. SURGERY (aggressive)
redefine basal cell tumors
second most common skin tumor in catsredefined as trichoblastomagenerally benign
perianal gland adenoma
3rd most common cutaneous tumor in DOGSperianal hepatoid gland tumorsarise from modified sebaceous glands in dermis surrounding anuspredominately SEX HORMONE DEPENDENT (stimulated by androgens, suppressed by estrogens)INTACT MALES presdisposed90% cured with castration
perianal gland adenocarcinoma
NOT hormone dependentrarefaster growth rate, mets occur, more invasive
canine anal sac adenocarcinoma (apocrine gland adenocarcinoma of the anal sac)
older female dogs, no hormone dependencemetastatic rate 36-96% (regional sublumbar nodes)paraneoplastic hyperCa 27%complete excision difficult—follow up with chemo (mitoxantrone) and/or radiation therapy