MoD session 8: neoplasia 1

Question 1

Define neoplasm

Answer 1

An irreversible, abnormal growth of cells that persists after the initial stimulus is removed.

Question 2

Define malignant neoplasm

Answer 2

An irreversible, abnormal growth of cells that persists after the initial stimulus is removed AND that invades the surrounding tissue with potential to spread to distant sites. A.k.a cancer

Question 3

Define tumour

Answer 3

Any clinically-detectable lump or swelling. One type of neoplasm

Question 4

Define metastasis

Answer 4

A malignant neoplasm that has spread from its original (primary) site to a new, non-contiguous (secondary) site

Question 5

Define dysplasia

Answer 5

A pre-neoplastic alteration in which cells show disordered tissue organisation. NOT neoplastic as change is reversible (as is the result of a stimulus, rather than being autonomous); can however change into carcinoma in situ (cancer that hasn’t invaded basement membrane), then invasive carcinoma (invades basement membrane)

Question 6

Characteristics of a benign tumour

Answer 6

Remains confined to site of origin; does not produce metastases
Grows in a confined local area
Pushing outer margin (pushes and squashes rather than invades and destroys, so rarely dangerous)
Cells are well-differentiated: closely resemble parent

Question 7

Characteristics of a malignant tumour

Answer 7

Irregular outer margin and shape
May have areas of necrosis (often grows away from blood supply) or ulceration (break in epithelial surface)
Range from well to poorly-differentiated: differentiation is indicated by grade. High grade=poor differentiation and for many this correlates with prognosis

Question 8

What does anaplastic mean?

Answer 8

Cells with no resemblance to any other tissue

Question 9

What changes are seen with worsening differentiation?

Answer 9

• cells have increasing NUCLEAR:CYTPLASMIC RATIO
• HYPERCHROMASIA: increased nucleus staining
• more MITOTIC FIGURES
• variation in size and shape of cells and nuclei: PLEOMORPHISM

Question 10

How do mutations cause neoplasia?

Answer 10

Accumulation of mutations in somatic cells

INITIATORS (mutagenic agents) and PROMOTERS (cause cell proliferation) are needed to cause an expanded monoclonal population of mutant cells. Main initiators are chemicals/infection/radiation but some of these can also act as promoters

Mutations can be classed as passenger mutations (in genes unimportant to proliferation) or driver mutations (in genes involved in proliferation)

Neoplasms emerge from this monoclonal cell population through PROGRESSION: by chance/exposure to more mutations/failure of repair. It is thought neoplasia occurs by accumulation of mutations (~5-7 rate-limiting mutations) until malignant

Question 11

How do inherited cancers develop?

Answer 11

Germline mutations are inherited, so neoplastic cells get a “head start”

Question 12

Describe the evidence supporting the monoclonal theory of neoplasia

Answer 12

• study of X-linked dream for glucose 6-phosphate dehydrogenase in tumour tissue from women
• gene has several alleles encoding different isoenzmes
• early in female embryogenesis one allele in each cell is randomly inactivated: LYONISATION
• in heterozygous women that happen to have one allele encoding a heat-stable isoenzyme and one a heat-labile isoenzyme, normal tissues will be a patchwork of both
• neoplastic tissues only express 1 isoenzyme indicating a monoclonal group of cells
• heat stable will work heated, heat labile will not. Apply colour to see which allele was inactivated

Question 13

General rule for neoplasm naming

Answer 13

Benign: end in -oma
Malignant: end in -carcinoma (epithelial) or -sarcoma (stromal)

Carcinomas are in situ if have not invaded basement membrane, or invasive if penetrated through basement membrane

Blastomas: mainly in children, formed from immature precursor cells e.g. nephroblastoma

Question 14

Describe the nomenclature for epithelial neoplasms

Answer 14

Benign

• stratified squamous=SQUAMOUS PAPILLOMA (finger-like projections. E.g. skin, buccal mucosa)
• transitional: TRANSITIONAL CELL PAPILLOMA e.g. bladder mucosa
• glandular: ADENOMA e.g. adenomatous polyp of colon

Malignant: carcinoma. (carcinoma not all cancer, but 90%)

• strat sq= SQUAMOUS CELL CARCINOMA (e.g. skin, larynx, oesophagus, lung)
• transitional=TRANSITIONAL CELL CARCINOMA (bladder, ureter)
• glandular=ADENOCARCINOMA (stomach, colon, lung, prostate, breast, pancreas, oesophagus)
• other: BASAL CELL CARCINOMA (skin), MALIGNANT MELANOMA (in melanocytes)

Question 15

Nomenclature of connective tissue neoplasms

Answer 15

Benign:

• smooth muscle: leiomyoma
• fibrous tissue: fibroma
• bone: osteoma
• cartilage: chondroma
• fat: lipoma (most common benign tumour, foud in all tissue planes, rarely becomes a liposarcoma)
• nerve: neuroma
• nerve sheath: neurofibroma
• glial cells: glioma

Malignant:

• smooth muscle: leiomyosarcoma
• fibrous tissue: fibrosarcoma
• bone: osteosarcoma
• cartilage: chondrosarcoma
• fat: liposarcoma
• glial cells: malignant glioma

Question 16

Nomenclature of lymphoid/haematopoietic neoplasms

Answer 16

All malignant
Lympoid: lymphoma. Occurs in lymphoid tissue (usually lymph nodes). Hodgkin’s and non-Hodgkin’s types
Haematopoietic: leukaemia “liquid neoplasm”. Starts in bone marrow then abnormal cells enter blood. Acute or chronic, myeloid or lymphocytic

Question 17

Germ cell neoplasm nomenclature

Answer 17

> 1 neoplastic cell type from >1 germ cell layer
Benign: benign teratoma (dermoid cyst) in ovary. Can contain hair, teeth, thyroid tissue, connective tissue, fat, muscle
Malignant: malignant teratoma (testes), seminoma (testicular slow-growing cancer, usually painless lump)

Question 18

Neuroendocrine tumour nomenclature

Answer 18

Arise from cells distributed throughout the body. Terminology still evolving
Includes:
-carcinoid tumour (usually in GI tract and lung)
-pheochromocytoma (adrenal)
-small cell carcinoma of bronchus

Question 19

What does scirrhous mean?

Answer 19

Hard or indurated tumour, due to abundance of connective tissue and collagen

Question 20

What is a polyp?

Answer 20

An abnormal growth of tissue projecting from a mucous membrane with a stalk

Question 21

What is rhabdomyosarcoma/rhabdomyoma?

Answer 21

Malignant/benign tumour of striated muscle

Question 22

Haemangioma

Answer 22

Benign tumour of blood vessels

Question 23

Angiosarcoma

Answer 23

Cancer of inner lining of blood vessels
Can occur in any area, but usually skin of scalp and face
Can present as skin infection or a non-healing lesion or a soft lump

Question 24

Mesothelioma

Answer 24

Cancer of mesothelium: the vessels and surface coverings

Question 25

Meningioma

Answer 25

Benign tumour of brain coverings

Question 26

What is a naevus?

Answer 26

Benign tumour of melanocytes

Question 27

Myeloma

Answer 27

Cancer of the bone marrow plasma cells
Incurable
Often have bone disease, anaemia, recurrent infection, hypercalcaemia

Question 28

Hamartoma

Answer 28

A benign vascular tumour that resembles a neoplasm but results from faulty development in an organ

Question 29

Choriocarcinoma

Answer 29

Cancer of the placental epithelium

Question 30

Astrocytoma

Answer 30

Cancer of astrocytes

Type of glioma

Question 31

Colorectal carcinoma

Answer 31

Cancerous growth of colon, rectum and appendix
Usually adenocarcinomas
Symptoms include rectal bleeding, palpable mass, change in bowel habit

Question 32

Uterine leiomyoma

Answer 32

Benign tumours of the uterus due to overgrowth of smooth muscle. May grow very big and cause infertility. Oestrogen-dependent
Common name-fibroids

Bundles of spindle cells with blunt-ended nuclei. May cause severe pain if large causing ischaemia, or some fibroids can twist and impair blood flow

Question 33

Osteosarcoma

Answer 33

Bone cancer
Especially happens at metaphysis, and around the knee and proximal humerus
Primary most common cancer in teenagers, adults usually have it as a secondary metastatic site

Question 34

Mature cystic teratoma of ovary

Answer 34

Benign tumour of totipotent cells in ovary
Also called dermoid cyst
Almost-always lined by skin-like structures

Question 35

Struma ovarii

Answer 35

Rare teratoma of usually ovaries but can be in other areas, with mostly thyroid tissue composition–>can cause hyperthyroidism
Usually benign but can be malignant

Question 36

Chronic lymphocytic leukaemia

Answer 36

Cancer of mature lymphocytes

Usually insiduous onset, more likely to affect adults