What are the 3 types of tumors? Characterize each.
- Epithelial: skin, resp, GI, urinary tract, glands, organs
- Mesenchymal: mesenchymal and connective tissue
- Round cell: hematopoietic and mesenchymal origin
What is your first step when approaching a patient with a possible skin tumor?
FNA and cytology
Tumors of epithelial tissue are called __________ and are characterized by... (5)
carcinomas; intercellular junctions, NO elaborate extracellular matrix, exfoliate well, distinct cytoplasmic borders of individual cells, arranged sheets or clusters
Tumors of mesenchymal tissues are called __________ and are characterized by... (4)
sarcoma; cells are embedded in extracellular matrix, exfoliate poorly, NO intercellular junctions, spindle shaped cells
Discrete round cell tumors are called __(5)__ and are characterized by... (4)
lymphoma, MCT, histiocytic tumors, plasma cell tumors, TVT; exfoliate easily, individualized cells in noncohesive monolayers, round, distinct cytoplasmic margins
What if a diagnosis cannot be obtained with cytology?
surgical biopsy and histopathology- incisional biopsy vs excisional biopsy
What should you not do when biopsying a potential skin tumor?
do not biopsy in a manner that may prevent or interfere with a definitive or curative surgical procedure later
_________ cures more cancer than any other treatment modality.
How is staging of a tumor performed? (4)
- FNA of the local draining lymph node
- thoracic rads
- abdominal US +/- FNA of liver/spleen
- CT or MRI for large infiltrative tumors
What are the treatment modalities for skin tumors, and what does their use depend on?
surgery, radiation, chemotherapy; dependent on what type of tumor it is and where it is (staging)
What does "in situ" mean?
carcinoma that has NOT penetrated the basement membrane of the epithelium
Tumors arising from follicular epithelium in SA. (2)
SCC in situ, SCC
Tumors arising from the hair follicle in SA. (1)
Tumors arising from glandular structures in SA. (2)
sebaceous gland tumors, apocrine gland tumors [adenocarcinomas]
Tumors of the ear canal. (1)
ceruminous gland tumors
Various tumors of the skin in SA. (5)
hemangioma and hemangiosarcoma, melanoma, histiocytoma, plasma cell tumor, lymphoma
SCC in situ is primarily a disease of ________, causing... (4)
cats; erosions of the epidermis, proliferation, crusted plaques, +/- pain
What is Actinic Keratosis?
SCC in situ that arises secondary to UV exposure--> solar elastosis and fibrosis of the skin [usually occurs on lighted haired and pigmented skin]
Bowen's Carcinoma is a type of __________ that is __________, including... (2)
SCC in situ; occurring in multiple sites; haired and unhaired areas, areas with and without UV exposure
What are clinical manifestations of Bowen's Carcinoma? (6)
heavily scaled, crusted, and pigmented papules and plaque +/- erosion
Describe prognosis for Bowen's carcinoma.
animals continue to develop lesions over time regardless of treatment
Describe the behavior and prognosis of SCC in situ?
non-invasive, no mets but will metastasize if left untreated
What is the treatment of choice for SCC in situ; what are adjunctive therapies? (5 adjuncts)
surgery!; imiquimod cream, strontium-90 plesiotherapy, photodynamic therapy, cryosurgery
What is cryosurgery?
destruction of tissue with controlled use of freezing and thawing, 3 cycles, development of ice crystals intra and extra-cellularly that results in cell death
With what lesions is cryotherapy sometimes attempted?
superficial lesions that are <4mm in diameter
What is the etiology of SCC in cats?
What are clinical presentations of SCC in cats?
erythemic, ulcerated, crusted lesions
What is the treatment of choice, behavior, and prognosis of SCC in cats?
- 1.7 year survival
- mets at TOD- 40%
What is the treatment of choice (1) and adjunctive (3) treatments of SCC in cats?
- External beam radiation therapy, strontium-90 plesiotherapy for invasive SCC, cryosurgery
Describe the presentation and behavior of SCC in retrievers.
nasal planum, locally invasive and aggressive, mets in 25% of cases [not associated with UV]
Describe the presentation and behavior of SCC in bloodhounds, bassetts, poodles, and breeds with light pigmentation.
cutaneous SCC, mets rarely [may be associated with UV]
What is the treatment of choice for SCC in dogs and what is an adjunctive therapy?
- Choice: surgery
- Adjunctive: chemotherapy [radiation does not seem effective]
What 3 tumors arise from the hair follicle?
trichoblastoma, trichoepithelioma, malignant trichoepithelioma
Trichoblastoma occurs when there is differentiation to the...
hair germ of the developing hair follicle.
How common are trichoblastomas, and how to they present?
- common in dogs and cats
- Dogs- head and neck
- Cats- anywhere on body
Describe the behavior and treatment of trichoblastoma.
benign in cats and dogs; surgery is treatment of choice
Trichoepithelioma occurs when there is differentiation to...
all segments of the hair follicle.
Trichoepithelioma is a _________ tumor unless it is classified as _____________, which is...
benign; malignant trichepithelioma; invasion into surrounding tissues and lymphatic involvement.
What is the treatment for trichoepithelioma?
- benign: surgery in dogs and cats
- malignant: highly metastatic, wide surgical excision, +/- adjuvant therapy
Sebaceous adenomas are __________ in dogs and occur on the __(3)__; treatment of choice is ___________.
common (rare in cats); limbs, trunk, eyelids; surgery
Describe the behavior and treatment for sebaceous carcinoma.
local infiltration but rarely metastatic; surgery with side margins
Describe the behavior and treatment of apocrine gland tumors.
- locally invasive, low rate of metastasis, but usually malignant (ie. the invasive part)
- wide surgical excision
- [REMEMBER: THESE ARE DIFFERENT FROM ANAL SAC APOCRINE ADENOCARCINOMA]
What tumors occur in the ear canal?
ceruminous gland adenoma or adenocarcinoma
How do ceruminous gland adenomas usually present?
- Dogs: exophytic, pedunculated, +/- ulcerative
- Cats: darkly pigmented, small, multiple
What is the treatment for ceruminous gland adenoma?
What breeds are predisposed to ceruminous gland adenocarcinoma?
cocker spaniel, GSD
Describe the behavior and treatment of ceruminous gland adenocarcinoma.
- locally invasive, met to local lymph nodes and lungs
- complete surgical excision- bulla osteotomy, radiation therapy
What are prognostic factors of ceruminous gland adenocarcinoma?
- Cats: mitotic index of 2 or less, presence of neuro signs, histology, extension beyond ear canal
- Dogs: extension beyond ear canal
What causes dermal hemagiosarc?
exposure to UV light, esp in areas with minimal pigmentation and thin hair coats (more common in dogs)- inguinal, axillary region, muzzle
Describe the behavior of dermal hemangiosarcoma.
without clinical or histologic evidence of subdermal infiltration (ie. does not penetrate the basement membrane)--> BENIGN (opposite to visceral hemangiosarc)
What is the treatment for dermal hemangiosarc?
- surgical excision
- if subdermal invasion/ involvement of SQ tissue- radiation therapy
Describe methods of prevention of dermal hemangiosarc.
sunsuit, keep dog in shade during high intensity sunlight times of day
Melanomas involving ______________ often have benign behavior.
haired skin (not in proximity to mucosal margins)
What is the treatment for melanoma?
surgical excision with 1-2cm margin often curative
Where does histiocytoma arise from?
originate from epidermal dendritic or Langerhan cells
What is the behavior and treatment of histiocytoma?
benign; sometimes spontaneous regression, sometimes surgery
Where do histiocytomas often arise?
head and limbs of young dogs
Indications for surgery to remove histiocytoma. (6)
rapid growth, ulceration/ infection, location (that will make it hard to remove if it gets bigger), development in an older patient, cytology not conclusive, failure to resolve in a timely fashion
Cutaneous plasma cell tumors are ____________ and most commonly occur in the following locations...
extramedullary plasmacytoma (EMP); limbs, head, ears
What do cutaneous plasma cells tumors look like?
solitary, smooth, raised pink nodules
Describe the behavior and treatment of cutaneous plasma cell tumors.
- typically benign (rare form of multiple cutaneous plasmacytoma that has more aggressive biological behavior)
- surgery typically curative
Cutaneous lymphoma is ____________; it can be __________ or __________ and typically presents as...
epitheliotropic T cell lymphoma; generalized; multifocal; nodules, plaques, ulcers, erythemic, or exfoliative.
With cutaneous lymphoma, there may be ____________ involvement in late stages of dz.
peripheral lymph node
What are the clinical stages of disease with cutaneous lymphoma?
- 1. scaling, alopecia, pruritus
- 2. erythema, thickened, ulcerated, exudative
- 3. proliferative plaques and nodules with progressive ulceration
Describe the treatment of cutaneous lymphoma. (4)
chemotherapy, radiation therapy (palliative, if there are large, ulcerated, painful lesions- local radiation), surgery, supportive care (antibiotics for secondary infection, analgesics)
What is the most common skin tumor in dogs?
mast cell tumors
What is the usual signalment of dogs with mast cell tumors?
8-9 years old, brachycephalics, retrievers, shar-pei
Majority of mast cell tumors are found in the __(2)__ and are usually _________.
skin and SQ; solitary
What is a characteristic finding when aspirating a mast cell tumor in a dog?
release of mast cell mediators (histamine, etc) when manipulated--> swelling and bleeding
How are mast cell tumors diagnosed?
- FNA: round cells, numerous granules (unless poorly differentiated, more aggressive type), may not stain with diff-quik (send to lab for wright's stain)
- Biopsy: avoid if you can b/c they heal poorly and bleed/ooze chronically; do biopsy if you can't diagnose with cytology
Describe the staging of mast cell neoplasia in dogs. (4)
- minimum database
- lymph node aspirate: of draining lns, presence of mast cells may indicate systemic disease (may also just be reactive ln), may need biopsy for definitive
- thoracic rads: rarely spread to thoracic lns
- abdominal US: aspirate any suspicious organs, aspirate spleen and liver (even if normal) if suspicious of systemic involvement
Prognostication should be done prior to ___________ because...
surgery; surgery can cause inflammation of lns and make interpretation of cytology more difficult, if severe systemic dz then surgery is futile
What are prognostic indicators with mast cell tumors?
- Histological grade: after incisional or excisional biopsy,morphologic characteristics of neoplastic cells, number of mitotic figures, and extent of tumor invasion into underlying tissues
- Patnaik: not reliable in predicting the behavior of grade 2 tumors
- Kupel: more objective based on # of mitotic figures, multinucleated cells, biazzare nuclei, and kayomegaly
- Mitotic index: # of mitoses per 10hpf
What information should you ALWAYS get when you send out mast cell tumors for histopathology? (3)
Patnaik grade, Kupel grade, Mitotic index
What are prognostic factors for clinical staging?
- multiple tumors, LN metastasis, anatomic location (oral cavity, nail bed, muzzle, inguinal, preputial, and perineal worse but should be ok if you treat locally), mast cell tumors in viscera- much worse prognosis, growth rate, breed (brachycephalic)
- KIT- receptor tyrosine kinase critical for development and growth of normal mast cells; KIT mutations in 20-30% of high grade mast cell tumors
KIT mutations are associated with... (3)
higher rate of local recurrence, higher risk of mets, shorter overall survivial
What are goals of txt of canine mast cell tumors?
- provide supportive care to prevent clinical signs
- adequate local tumor control
- address obvious/ potential metastatic dz
- aggressive multi-modal therapy appears to inc survival time
Describe supportive care for canine mast cell tumors. (4)
- H2 antagonist/ PPI: Famotidine, Omeprazole- GI protection due to inc gastrin release (inc histamine)
- H1 antagonist: Diphenhydramine- decrease swelling
- Gastroprotectant: Sucralfate
- Anti-emetics: Maropitant, Ondansetron, Metronidazole
Describe the surgical treatment of mast cell tumors in dogs.
wide surgical excision for all tumors
Describe the use of radiation therapy in the treatment of canine mast cell tumors.
- eliminates residual microscopic disease after incomplete surgical excision
- palliation of large tumors
Describe chemotherapy used to treat canine mast cell tumors. (4)
- Corticosteroids: reduce tumor-associated edema and mediator production, high response rate
- Vinblastine: microscopic disease
- CCNU/ Lomustine: grade 2 and 3 that fail other treatment, may cause BM toxicity
- KIT Inhibitors: Gleevec, Palladia, Kinavet; lots of side effects
Overall, describe treatment of canine mast cell tumors.
treatment should be multi-modal, staging is critical for developing an effective plan
What are the 3 manifestations of feline mast cell tumors?
cutaneous, splenic (lymphoreticular or visceral), intestinal
Clinical signs of mast cell tumors in cats.
solitary, raised, firm, hairless masses, +/- ulceration, +/- pruritic; head and neck most common location
What are the variants of feline mast cell tumors? (3)
- mastocytic compact variant: well differentiated, heavily granulated, benign
- mastocytic diffuse variant: high mitotic index, pleomorphism, mets to ln, spleen, BM
- histiocytic variant: usually spontaneously regress
What factors correlate with an unfavorable outcome with feline mast cell tumors? (5)
multiplicity of lesions, pleomorphic phenotype, KIT score, Ki67 index, mitotic index (strongest predictive value)
What is the treatment for feline cutanoeous mast cell tumors?
- surgery is definitive therapy (except histiocytic, wait and see for these)
- if KIT mutations, maybe KIT inhibitors if surgery is not logical due to location
In cats with multiple cutaneous mast cell tumors, evaluation of the ___________ is warranted to determine involvement.