neoplastic disease of the GI tract revision W8 Flashcards
what is hyperplasia
tissue growth due to an increase in cell number (not increase in cell size - hypertrophy)
can be physiological or pathological
what is metaplasia
change from one fully differentiated cell type to another fully differentiated cell type
what is neoplasia
the development of a neoplasm, ie an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissue, and which persists even after the evoking stimulus (if known) is removed.
what is dysplasia
descriptive term used by pathologists to indicate a pattern of disordered growth and differentiation, typically applied to epithelial tissue.
doesn’t describe a pathological process, rather an appearance seen down the microscope.
dysplasia and neoplasia?
cells showing dysplasia may already be neoplastic, or show pre-neoplastic changes, however dysplastic changes can revert back to normal in some cases
dysplasia classifications?
low grade and high grade - based on the extent by which the growth pattern deviates from that of normal tissue.
what is severe dysplasia often referred to in epithelial tissue?
carcinoma in situ (also known as intraepithelial neoplasia)
dysplasia key features?
hyperchromatism (increased staining of nuclei reflecting increase in DNA content)
nuclear pleomorphism (variation in nuclear shape/size)
loss of orientation (loss of polarity)
cell crowding and stratification (loss of normal contact inhibition)
increased/abnormal mitotic figures (increased cell proliferation)
how are cancers named?
malignant neoplasm in :
epithelial tissue -> carcinoma
soft tissue -> sarcoma
haematological -> lymphoma/leukaemia
common types of carcinoma?
adenocarcinoma = tumours showing glandular (columnar) cell differentiation
squamous cell carcinoma
common types of sarcoma?
osteosarcoma (bone)
chondrosarcoma (cartilage)
leiomyosarcoma (smooth muscle)
what causes neoplasia
chemical carcinogens
physical agents
infections
inherited susceptibility
hormonal stimulation
mechanisms of neoplasia?
direct/indirect damage to DNA
reduced ability to repair DNA damage
increased stimuli to proliferate
reduced ability to inhibit growth
defects in apoptosis
benign neoplasm features?
well differentiated
slow growing
normal mitotic figures
no local invasion!!!!
no metastasis!!!!
malignant neoplasm features?
lack of differentiation
erratic/rapid growth
may be abnormal mitotic figures
local invasion!!!!
metastasis!!!!
routes of metastasis?
lymphatic (common)
vascular (normally veins)
perineural and intraneural
spread across cavities
iatrogenic
effects of benign tumours?
bleeding - erosion and ulceration
space occupying lesions within skull
compression of adjacent structures
obstruction of lumina (eg intrassusception in GI tract
hormonal effects (increased/decreased production)
what is intrassuception?
polyp propelled forward by waves of peristalsis, causing the bowel to “telescope”. this causes obstruction of the lumen and compresses the venous drainage, leading to ischaemia.
2 categories of ‘borderline’ tumours?
tumors that show extensive local invasion, but almost never metastasise (prone to local recurrence if incompletely excised)
tumours that appear entirely benign at time of diagnosis, but then develop distal metastatic disease (often late after diagnosis).
grading of malignant neoplasms?
an attempt to predict the aggressiveness of a cancer based on its microscopic features.
high grade cancers are typically poorly differentiated, worse prognosis.
low grade cancers are well differentiated, better prognosis.
most important prognostic feature of cancer?
staging (based on TNM classification)
