Introduction
    

Introduction:

One of the basic distinctions that must be made when considering neoplasia is whether the tumour is benign or malignant. Some of the criteria used to make that distinction are outlined in Table 1.
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Table 1: Criteria used for classification of neoplasms as Benign or Malignant

Criterion

Benign

Malignant

Growth:

rate

margins

slow

circumscribed
encapsulated

rapid

infiltrative

Mode of Growth:

metastases

recurrence

never

rare

common

common

Cellular Characteristics:

architecture

nuclear chromatin

nuclear size

nuclear shape

nucleoli

mitotic figures

near normal

near normal

near normal

uniform

normal, small

few, normal

abnormal

hyperchromatic

enlarged

pleomorphic

large/multiple

frequent, abnormal

Stromal Features:

blood supply

connective tissue

invasion

necrosis

adequate

often abundant

absent

rare

often scanty

variable

common

common

Anaplastic features of a squamous cell carcinoma (= malignant tumour):

  • large central nucleoli (in some cells, multiple nucleoli are present – red arrowheads)

  • Abnormal mitotic figure (blue arrowhead)

 

Anaplastic features of a poorly differentiated fibrosarcoma. Note the atypical mitotic figures (black arrows) and the multinucleate and uninucleate giant tumour cells (red arrowhead). There is variation in cell shape and size.

 

Sertoli cell tumours often incite a large amount of collagen to be deposited by (non-neoplastic) mesenchymal cells. (x40)

Slide Ref 443-03

 

This is an area of necrosis within a malignant osteosarcoma. Malignant tumours often outgrow their blood supply and undergo ischaemic necrosis. (x40).

Slide Ref 95v972B

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