Neoplasia means literally new growth

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Neoplasia means literally new growth Not all
new growths are neoplasms Tumor originally
meant swelling now it is synonymous with
neoplasm Oncology is the study of
tumors Neoplasms may be benign or
malignant Malignant neoplasms are cancer Willis
defined a neoplasm as an abnormal mass of tissue,
the growth of which exceeds and is uncoordinated
with that of the normal tissues and persists in
the same excessive manner after cessation of the
stimulus which evoked the change. Robbins adds
that the abnormal mass is purposeless, preys on
the host, and is virtually autonomous.
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Stages of neoplastic evolution 1. Physiologic
growth persistent, periodic, blastic,
regenerative. e.g. Squamous metaplasia, nevus,
enterocyte, lymphocyte 2. Dysplasia abnormal
growth and differentiation. e.g. Intraepithelial
neoplasia I and II, dysplastic nevus, aberrant
crypt focus, myelodysplastic syndrome 3.
Intracompartmental neoplasia. e.g. CIN III
carcinoma in situ, radial growth melanoma,
adenomatous polyp, lymphoma 4. Invasive
cancer. e.g. squamous carcinoma, vertical growth
melanoma, adenocarcinoma 5. Metastatic Cancer
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Benign versus malignant neoplasia

• Benign
• Well-differentiated although dysplasia is present
• Progressive, slow growth with normal mitosis
• Not invasive or metastatic

• Malignant
• Aberrant differentiation
• Erratic growth abnormal mitosis
• Invasive and may metastasize

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Naming neoplasms

• Benign neoplasms generally add oma
• e.g. papilloma, lipoma, leiomyoma
• Malignant neoplasms epithelial cells become
  carcinomas, mesenchymal cells become sarcomas
• e.g. papillary carcinoma, liposarcoma,
  leiomyosarcoma
• Exceptions
• e.g.hepatoma, melanoma, lymphoma

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Mechanisms of carcinogenesis   Steps and
stages initiation promotion progression meta
plasia/hyperplasia dysplasia neoplasia/anaplasia

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Two-stage model of mouse skin carcinogenesis
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Phenobarbital promotes hepatocarcinogenesis
Plus phenobarbital
Minus phenobarbital
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