Histopathology and Key Terminology ☺️ Flashcards
Neoplasia
New growth
- monoclonal proliferation of cells => tumour, mass
- can be benign or malignant
Growth exceeds stimulus => autonomous
-genetically similar to cell of origin
Hyperplasia
Hypertrophy
Increase in cell number proportionate to stimulus
Increase in cell size proportionate to stimulus
Choriostoma
Hamartoma
Teratoma
Tumour composed of normal cells/tissue present in an abnormal place
Tumour composed of disorganised growth of different cell types normally present in that organ
Tumour of derivatives of ectoderm, endoderm, mesoderm
Dysplasia
Abnormal growth
- may form a benign neoplasm - adenoma
- often a precursor of malignant neoplasms
How to classify neoplasms
Biological potential/behaviour
- malignant - potential to metastasise
- benign - do not
- borderline - uncertain malignant potential
Cell of origin
Cell of origin
- 3 main types of epithelium
- how to name benign and malignant epithelial growth
Squamous epithelium =>
- squamous papilloma
- squamous cell carcinoma
Glandular epithelium =>
- adenoma
- adenocarcinoma
Transitional epithelium =>
- transitional cell papilloma
- transitional cell carcinoma
Majority of malignant tumours are carcinomas
Cell of origin
- type of mesenchymal tumour (benign and malignant)
- fat
- lymphatic vessels
- blood vessels
- nerves
- bones
- cartilage
- smooth muscle
- skeletal muscle
Fat =>
- lipoma
- liposarcoma
Vessels =>
- lymphatics - lymphangioma
- lymphangiosarcoma
- blood - hemangioma
- hemangiosarcoma
Nerves =>
- neuroma
- malignant peripheral nerve sheath tumour (MPNST)
Bones =>
- osteoma
- osteosarcoma
Cartilage =>
- chondroma
- chondrosarcoma
Smooth muscle =>
- leiomyoma
- leiomyosarcoma
Skeletal muscle =>
- rhabdomyoma
- rhabdomyosarcoma
Cell of origin
- types of tumour that do not have benign versions
- primitive lymphoid/myeloid cells
- mature lymphocytes
- plasma cells
- mesothelium
- melanocytes
- germ cells
Primitive lymphoid/myeloid cells => leukemia
Maturę lymphocytes => lymphoma
Plasma cells => myeloma
Mesothelium => mesothelioma
Melanocytes => melanoma
Germ cells => teratoma, seminoma, choriocarcinoma
Benign neoplasm findings
- clinical presentation
- macroscopic
- microscopic
- behaviour and prognosis
- management
Well demarcated, circumscribed
Cream coloured
Multiple
Close resemblance to cell of origin
Uniform growth pattern
Cytology
- normal nuclear size
- smooth nuclear membrane
- normal nuclear chromatin
- normal nuclei
- normal rate of mitosis
Tumour stroma
-no necrosis, hermorrhage, fibrotic reaction
Malignant neoplasm findings
- clinical presentation
- macroscopic
- microscopic
- behaviour and prognosis
- management
Poorly defined
Infiltrating into surrounding areas
Black necrotic areas - due to insufficient blood supply
Poor resemblance to cell of origin if high grade
Irregular growth pattern
Cytology
- increased nuclear size due to increased size
- irregular nuclear membrane
- very dark nuclear chromatin
- enlarged nucleoli
- high no of cells in mitosis
Tumour stroma
- coagulative necrosis (due to ischemia) and hemorrhage
- fibrotic reaction
Principles of carcinogenesis
Initiation - non lethal genetic damage to cell
Classes of genes damaged
- protooncogenes => promote growth
- tumour suppressor genes => growth inh
- apoptosis regulators
- DNA repair genes
Clonal expansion => neoplasm with abnormal DNA
Driver mutations, epigenetic aberrations
-stepwise accumulation of complementary mutations/epigenetic changes => formation of subclones
All subclones undergo Darwinian selection
Mechanisms of spread of cancer cells
Local invastion
Metastatic spread
-via lymphatics (mainly carcinomas) or blood (carcinomas and sarcomas
Extravascular migratory metastasis - creep around the blood vessels
Perineurally - creep around the nerves
Transperitoneally
Aerogenous - from one lung lobe to another
Investigations
- what is the key investigation needed for a cancer diagnosis
- what would you need
Cytology, histological diagnosis needed!
Types of cytology samples
- naturally exfoliated - urine, sputum
- artificially exfoliated - broncheolavage, brushings, scraping
- FNA
Types of histology samples
- punch biopsy for mucosal, skin surface lesions
- core biopsy for deeper lesions, connective tissue
- incision/excision biopsy with endoscopic imaging
- surgical excisions
What investigations would you also like to do once a diagnosis of cancer has been reached
Flow cytometry on FNA - diagnose non Hodgkin lymphoma Immunohisto/cytochemistry - use of ABs Molecular diagnostics (PCR, insitu hybridisation, ELISA)
