Pathology Chapter: Neoplasia

10 Questions

What is the hallmark feature of anaplastic tumours?

Loss of tissue architecture and specialized functional activity

What is nuclear pleomorphism?

Variation in shape and size of nuclei

What is the normal nucleo-cytoplasmic ratio, and how does it change in malignant cells?

Normal ratio is 1:4 or 1:6, but it approaches 1:1 in malignant cells due to nuclear enlargement

What is the significance of abundant mitoses in tumour cells?

It reflects proliferative activity and rapid growth

What role do hormones play in tumour growth?

Hormones can influence growth rate, particularly in hormonally-responsive tissues

What is the difference in growth rate between benign and malignant tumours?

Benign tumours grow slowly, while malignant tumours grow rapidly and invade surrounding tissues

What is the significance of tumour giant cells?

They are a characteristic feature of malignant cells, containing a single large polypoid nucleus or multiple nuclei

What is metastasis, and which type of tumours can metastasize?

Metastasis is the spread of tumour cells to distant sites, and malignant tumours can metastasize

What is the usual fate of benign and malignant tumours if left untreated?

Benign tumours are not fatal unless in a vital area, while malignant tumours are usually fatal if not diagnosed and treated early

Why do benign tumours rarely recur after excision, whereas malignant tumours often do?

Benign tumours are slower-growing and less invasive, whereas malignant tumours are more aggressive and prone to recurrence

Study Notes

Neoplasia

Neoplasia means a new growth, and the new growth is called a neoplasm
In clinical practice, a neoplasm is often called a tumor, although tumor refers to all types of swellings, not just neoplasms
Oncology is the science of studying neoplasms
Cancer is the common term for all malignant tumors

Definition of a Neoplasm

A neoplasm is an abnormal new growth of cells independent of physiologic growth stimuli (autonomous)
It serves no useful purpose and its growth is uncoordinated with that of the surrounding tissue
Its growth persists after cessation of the stimuli that provoked its formation

Classification of Neoplasms

Neoplasms are classified according to their clinical behavior into:
- Benign
- Malignant
Classification is also based on the origin of the tumor, including:
- Epithelial origin
- Mesenchymal origin
- Germ cell origin

Characteristics of Benign and Malignant Tumors

Capsulation:
- Benign tumors: grow by expansion, with formation of a fibrous capsule, and have a plane of cleavage around the tumor
- Malignant tumors: grow by infiltration, destroy and penetrate the surrounding tissue, and do not develop a capsule
Differentiation and anaplasia:
- Benign tumors: composed of well-differentiated cells that resemble normal counterparts
- Malignant tumors: characterized by a wide range of parenchymal differentiation, from well-differentiated to undifferentiated
- Anaplasia implies dedifferentiation or loss of structural and functional differentiation of normal cells
Rate of growth:
- Most benign tumors grow slowly over a period of years
- Most cancers grow rapidly, spread locally and to distant sites (metastases), and eventually kill their host
Metastasis:
- Marks a tumor as malignant
- Malignant tumors can metastasize, with few exceptions
Recurrence after excision:
- Usually occurs in malignant tumors
Fate:
- Benign tumors: not fatal unless present in a vital area
- Malignant tumors: usually fatal if not diagnosed early and treated adequately