Anatomy Flashcards
Benign vs malignant
Benign:
-innocent behaviour
-localised lesion
-can affect surrounding tissues by mass effect
-never metastasise
Malignant:
-aggressive behaviour
-can invade local tissues
-can also spread to other parts of the body-metastasise
Tumour basic components
All tumours have 2 basic components
Tumour parenchyma: clonal expansions of neoplastic cells
Supporting stroma: non neoplastic connective tissue and blood vessels (abundant stroma-desmoplasia)
Benign tumours
Benign mesenchymal tumours
-fibroma, osteoma, leiomyoma, angioma
Benign epithelial tumours (based on macroscopic or microscopic elements)
-adenoma, cystadenoma, papilloma, polyp
Malignant tumours
Carcinoma= derived from epithelial cells
Sarcoma= derived from mesenchymal cells
Undifferentiated malignant tumours (poorly differentiated/unrecognisable cells)
Some tumours have more than one parenchymal cell type
-mixed tumours- derived from a single germ layer that differentiates into more than once cell type
-Teratomas- derived from more germ cell layers and hence composed of many parenchymal cell types
Major tumour classification
Classification depends on clinical behaviour and morphological evaluation
Categorised based on:
-degree of differentiation
-growth rate
-local invasions
-metastases
Enucleation: removal benign tumours with capsule
Mechanisms of cancer spread
Direct extension/local spread
-compress or invade surrounding structures
-seeding
Lymphatic spread:
-via lymph vessels/ndoes
-predictable
Haematogenous spread:
-via venous drainage
Direct extension/local spread
Tumour extends directly into surrounding spaces
Invasion of adjacent structures/organs
“Seeding” into body cavity
-detachment of cells from primary tumour, spread to surrounding structures
-eg peritoneal, pleural
Eg direct local invasion
Through wall of primary organ
Into adjacent organs/structures
Walls of containing region
Eg lung cancer: thoracic wall, mediastinum, root of neck
Eg bladder cancer: prostate, rectum, uterus, vagina, pelvic side walls
Eg peritoneal spread
Common primaries:
-gastrointestinal cancers- oesophageal, gastric, colorectal, pancreatic
-ovarian cancer
Cells implant into peritoneal surface of organs, such as liver, omentum (omental cake)
Transcoelomic spread
Omental cake: Radiologic sign indicative of an abnormally thickened greater omentum
Lymphatic spread of cancer
Cells detach from primary tumour
Enter lymph capillaries draining adjacent tissues (no functional lymphatics within actual tumour tissue)
Colonise distant tissues- lymph nodes
Need to know normal lymphatic drainage routes of tissues to be able to predict which lymph nodes malignancy will spread to
Sentinel lymph nodes
First lymph node/group of lymph nodes draining a tumour
Used to predict the likelihood of tumour spread (staging)
Identify and biopsy
If negative unlikely to have spread to lymphatics (therefore can avoid unnecessary lymph node removal)
If positive indicates lymphatic spread
Commonly used to help stage disease in: breast cancer, colon cancer, melanoma
Eg breast cancer:
-primary lymph node drainage= axillary lymph nodes
-identify sentinel lymph node by:
—blue dye (methylene blue)
—radioactive tracer (Tc 99)
Haematogenesis spread of cancer
Cells detach from primary tumour
Enter blood vessels draining tissue
Colonise distant tissues eg liver, lung, bone, brain
Need to know normal venous drainage routes of tissues to be able to predict which tissues malignancy likely to spread to
Haematogenosus spread to liver, lungs, bones
Liver:
-structures drained by portal venous system
-GIT tumours primarily metastasise to liver
-venous drainage via mesenteric veins, hepatic portal system , through liver sinusoids
Lungs:
-structures drained by systemic venous system
-enter right circulation via SVC/IVC thereby entering the pulmonary circulation
Bones:
-cancers commonly metastasising to bone include breast, lung, thyroid, kidney, prostate
-often spine
-can cause weakness in bones, pathological fractures
Investigation: anatomical considerations
Clinical assessment
-history and examination
Imaging
-endoscopy/colonoscopy/laparoscopy
-cross sectional imaging
Pathology:
-biopsy
-excision of tumour, lymph nodes
Chemotherapy:
-systemic vs local, cytotoxics, immunotherapy, hormone therapy
Radiotherapy:
-mapping- irradiate abnormal tissue, preserve normal surrounding tissue
Surgery:
-curative vs palliative, lymph node clearance, clearance margins, damage to surrounding structures
Anatomical impact of a tumour
Consider normal anatomy first
How might tumour impact on normal anatomy
What is normal histology/cancer histology
How might tumour spread:-
-locally, lymphatics, haematogenous
How will knowledge of anatomy influence investigations
How will knowledge influence treatment
Nerve supply- pain, infiltration
