3rd practical Flashcards
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Fibroma some info below!
TYPICAL HISTOLOGICAL FEATURES:
❑ Benign, well-circumscribed, but unencapsulated
❑ Composed of mature fibrocytes producing abundant collagen
❑ Arranged in interwoven fascicles and more rarely in whorls
❑ Neoplastic fibrocytes are:
❑ uniform
❑ low in number compared to the abundant dense collagen
❑ Oval, normochromatic nuclei
❑ indistinct cytoplasm that blends into the collagenous stroma
Fibroma
some info
Benign tumor of fibrocytes with abundant collagenous
stroma
❑ Uncommon in all domestic animals; most often seen in the
dog
❑ Predisposed breeds: Boxers, Dobermann pinschers and
Rhodesian ridgebacks
❑ More common in middle aged to older animals
Fibroma
TYPICAL GROSS FINDINGS:
• Intradermal or subcutaneous masses
• Solitary, soft to rubbery to firm, well-circumscribed
• Gray/white in cut surface
• Alopecia common; may be hyperpigmented
• Large tumours may be ulcerated due to self-trauma
Fibroma
Fibroma
Fibrosarcoma
❑Malignant mesenchymal tumor of fibroblasts
❑Usually low grade malignancy; low metastatic rate but high
recurrence rate
❑Variable presentation depending on species, age, site and
etiopathogenesis
❑Common in adult/aged dogs and cats, but uncommon in other
domestic species
❑Most common tumor of the cat and has increased in incidence
because of its association with injections
❑Predisposed dog breeds: golden retrievers and dobermann
pinschers
❑Can occur anywhere
❑ Dogs: most common on head and limbs
❑ Cat, post injection sites: interscapular, dorsal neck, shoulder,
flank and femoral areas
Fibrosarcoma
The most typical presentation is a
well‐circumscribed, firm white
mass in the subcutis or skeletal
muscle, with a cystic center
containing
thin watery or mucinous fluid.
Injection-site feline fibrosarcoma (ISS)
At low magnification, the tumor
is circular. When in the subcutis,
it is usually associated with and
extends downward from the
panniculus carnosus muscle.
The presence of peripheral aggregates of macrophages containing globular
gray/brown intracytoplasmic material (shown to be aluminum, a common vaccine
adjuvant) supports the diagnosis of vaccine‐associated sarcoma
Fibrosarcoma
TYPICAL GROSS FINDINGS:
❑ Can be circumscribed (poorly infiltrative) or infiltrative
❑ Small or extremely large and disfiguring
❑ Usually not encapsulated
❑ Cut surface
❑ gray-white and glistening
❑ +/-interwoven fascicular pattern
❑ Ulceration and alopecia are common
Fibrosarcoma
❑ TYPICAL HISTOLOGICAL FEATURES:
❑ Unencapsulated and locally invasive
❑ Highly cellular interlacing and intersecting
bundles of immature fibroblastic cells; “herringbone” pattern
❑ Variable pleomorphism, mitotic rate and amount of collagen
❑ Multinucleated cells with 2 to 3 nuclei are common (Cat > dog)
❑ +/- Peripheral aggregates of lymphocytes
Less-differentiated/more anaplastic form:
❑ Marked cellular and nuclear pleomorphism
❑ Ovoid, polygonal and multinucleated giant cells are seen
❑ Often with large round to oval nuclei and prominent nucleoli
❑ Mitotic figures are more frequent
Fibrosarcoma cat skin
More cellular interlacing and intersecting bundles of neoplastic
fibroblasts
Fibrosarcoma
Sarcoma gigantocellulare
Pleomophic sarcoma/anaplastic sarcoma with giant
cells info ?
Controversial entity: diverse group of neoplasms, leading
many to prefer the more generic diagnosis of
“undifferentiated pleomorphic sarcoma” or “anaplastic
sarcoma with giant cells
Within this there is a group a tumour of primitive
myofibroblast origin in dogs and cats that is analogous to the
classical human entity called malignant fibrous histiocytoma
(MFH)
However, the morphology of cells in this tumour merge easily
into anaplastic versions of many other mesenchymal and
histiocytic tumors in animals and humans, confounding
definitive diagnosis and making prognostication difficult
Immunohistochemical staining can sometimes more
specifically identify the histogenesis of the tumors
Classical MFH info?
TYPICAL HISTOLOGICAL FEATURES
Giant cell
▪ This is the most common subtype in cats
▪ These tumors have numerous multinucleated giant cells mixed
with spindle cells and mononuclear histiocytoid cells
▪ Although occasionally present, inflammatory cells are not a
consistent feature
Storiform‐pleomorphic
▪ This is the most common variant in the skin and organs of
dogs
▪ Fibroblast‐like cells are arranged in cartwheel (storiform)
patterns, mixed with histiocytoid cells and an infiltrate of
lymphocytes, plasma cells, neutrophils, and occasional
eosinophils
▪ Histiocytoid cells are frequently karyomegalic or
multinucleated, often with marked nuclear atypia
Classical MFH
Classical MFH
Classical MFH
Hemangioma
Benign tumours of vascular endothelium anywhere on the
body
Common in dogs; rare in other domestic animals
Dermal or subcutaneous
Slow growth; complete excision is curative
Occurrence in dermis of thinly haired lightly pigmented skin
suggests prolonged exposure to sunlight may be a factor → often
multiple , more superficially in the dermis and less circumscribed
Cattle, horse and pigs: can be congenital
Hemangioma
TYPICAL GROSS FINDINGS
❑Usually solitary, may be multiple
❑Subcutis: Moderately firm, well-circumscribed, reddish-black;
alopecia and ulceration uncommon
❑Dermis: Smaller and often sessile or pedunculated; alopecia,
hemorrhage/ulceration common
❑ Cut surface: honeycomb pattern of fibrous trabeculae separating blood-filled cavitie
Haemangioma
TYPICAL LIGHT MICROSCOPIC FINDINGS:
Two variants, based on size of vascular spaces:
❑ Cavernous: Large spaces separated by fibrous connective tissue
stroma
❑ Capillary: Little stroma; more cellular appearance, larger
nuclei
▪ Well-circumscribed neoplasm expands the dermis and subcutis
▪ Variably sized, blood-filled vascular spaces lined by a single
layer of well-differentiated endothelial cells
▪ Often see organized thrombi and foci of hemosiderosis
▪ Rare mitotic figures
Haemangioma cavernosum
mast cells
Adenoma simplex /simple adenoma
(dog, mammary gland)
Adenoma: well-demarcated, non-infiltrative nodular lesions
arising in the glandular tissue
▪ Simplex - composed of only one cell type
▪ Complex - composded of two cell types:
▪ luminal epithelial and myoepithelial cells
▪ Tubular adenoma: well-differentiated
neoplastic epithelial cells arranged in tubules
that occasionally contain secretion
▪ Other types: intraductal papillary adenoma, ductal adenoma,
fibroadenoma etc.
▪ Myoepithelioma: benign neoplastic proliferation of
myoepithelialc ells
Simple tubular adenoma (dog, mammary
gland)
Adenoma (dog, small intestine)
• Intestinal adenomas are rare in domestic animals
• Adenomas are common in humans and while the majority remain
asymptomatic, most intestinal adenocarcinomas develop from a
pre‐existing adenoma
• The proportion of intestinal adenocarcinomas that develop from
an asymptomatic adenoma in domestic animals is unknown
Adenocarcinoma cat large intestine
Canine intestinal adenocarcinoma
• Neoplastic cells are arranged within poorly formed glands or ducts
• Develop from the crypt epithelium and infiltrate underlying tissues
• Columnar to cuboidal neoplastic cells with marked dysplasia
• Acinar structures may contain goblet cells and accumulations of eosinophilic material
within the acinar lumen
• Deep invasion accompanied by marked fibroblastic response
(desmoplasia/fibroplasia)
• Neoplastic cells may spread within the mucosa of the intestine
• Often visible within submucosal lymphatics
Canine intestinal adenocarcinoma
Papilloma dog cavity
Papilloma
Papilloma
TYPICAL CLINICAL and GROSS FINDINGS:
Young animals (dogs< 3yrs.; bovine< 2yrs.)
Usually spontaneously regress
• Canine papillomas are most numerous on the lips and muzzle
• Bovine papillomas are flat with a broad base
TYPICAL LIGHT MICROSCOPIC FINDINGS:
Exophytic projections of mature, heavily keratinized, squamous
epithelium
on connective tissue cores
• Viral cytopathic effects in the upper levels of the epithelium:
giant keratohyalin granules and koilocytes
• Koilocytes: Keratinocytes with clear or amphophilic cytoplasm and
small smudged or vesiculate eccentric nuclei
• occasional basophilic intranuclear inclusion bodies
• eosinophilic intracytoplasmic inclusions may also be present
and composed of disrupted keratin
Papilloma
Squamous cell carcinoma
• Most common malignant skin neoplasm in cats
• Second most common skin neoplasm in dogs (following mast cell
tumour)
• Second most common oral tumor in dogs
• Arises from keratinocytes and occurs commonly in sun-damaged skin
• Usually preceded by solar keratosis; other factors that can influence its
occurrence include carcinogens, genetic factors, papillomaviruses and
epidermal trauma
• Highest incidence among short haired breeds with little skin
pigmentation in both dogs and cats
• SCC in pigmented areas more often are associated with papillomavirus
• Claw bed (subungual): most common neoplasm of the digit in dogs and
cats; often more aggressive with multiple digits affected and usually
associated with large breed, black-coated dogs
• SCC of the nasal planum arising in chronic cutaneous lesions of discoid
lupus erythematosus has been reported in dogs
Squamous cell carcinoma
TYPICAL CLINICAL FINDINGS:
• Typically locally invasive and slow to metastasize; however, SCCs
arising from internal sites such as tonsil, stomach, and urinary bladder
are more prone to metastasize
• May metastasize to the lungs and regional lymph nodes
TYPICAL GROSS FINDINGS:
• Variably sized, poorly demarcated, firm, white, nodular, papillary,
plaque-like, or crateriform masses that are often ulcerated and red
• Common sites in dogs include ventral trunk, limbs, digits, scrotum, and
lips
Squamous cell carcinoma
Squamous cell carcinoma
Squamous cell carcinoma
Squamous cell carcinoma
TYPICAL LIGHT MICROSCOPIC FINDINGS:
• Tumor cells breach the basement membrane to form islands, cords, and
trabeculae within the dermis that are usually contiguous with the overlying
• There is often formation of keratin pearls (concentric lamellae of keratin) and
prominent intercellular bridges; poorly differentiated tumours may only show
keratinization of individual cells (dyskeratosis)
• Tumor cells have vesicular nuclei with one or multiple very prominent nucleoli;
cytoplasm is typically abundant and eosinophilic
• Tumor cell invasion is usually associated with marked desmoplasia; mitotic figures
are often numerous and in proportion with the degree of anaplasia
Squamous cell carcinoma
