Basic Science / Structures > Neoplasia

Neoplasia

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concept: induction and proliferation

classification of tumors

derived from either: (distinct subsets with respect to biological behavior)

epithelial or connective tissue
blood forming and immunocytic tissues
CNS and PNS derived (glial cells, Schwann cells, and in rarer instances, ependymal and embryonic neuroblast tissues)

 

Benign:

adenomas:  glandular epithelium (of all 3 germ layers)
papilloma: squamous epithelium
fibroma, chondromas, osteomas: connective tissue

 

Malignant:

adenocarcinoma (carcinoma): glandular epithelium (of all 3 germ layers)
sarcoma: connective tissue  (fibrosarcoma, chondrosarcoma etc…)

 

 

anaplastic: used to describe tumors that do not resemble any known tissue (i.e. cant determine origin)

 

cell cycle of tumor cells ~ same length of time as normal cells
its the increase in fraction of tumor cells in division at any one time compared to normal tissue that gives expansive growth
tumor grows excessively because there are both larger numbers of cells growing at any one time and fewer cells undergoing terminal differentiation or apoptosis

 

p53 gene

“guardian of the genome”  (DNA damage induces p53 à  halts the cell cycle in G1)
transfection with mutant p53 “immortalizes” cells
the p53 mutations induced by UV radiation are found in >90% of human SCCs and are present in AKs

c-kit gene

encodes the cellular receptor tyrosine kinase for the ligand stem cell factor (AKA mast cell growth factor)
involved in pathogenesis of:  mast cell disease,  and piebaldism