3rd practical Flashcards
(36 cards)
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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
