Neoplasia I,II

Uncontrolled cell proliferation and growth that can invade other tissues

Swelling, can be benign or malignant - Could even be inflammatory or a foreign body

Neoplasia is a new growth which is not in response to a stimulus - Can be benign, premalignant or malignant - Can occur in any cell in any organ.

Neoplasms are comprised of proliferating cells that make up the parenchyma and supportive stroma made of connective tissue and blood vessels.

A neoplasm with potentially lethal, abnormal characteristics which has the ability to invade and metastasise.

A neoplasm which does not have the ability to metastasise and invade other cells is benign.

Some benign tumours can be locally harmful and destructive. They are not always harmless.

1. Differentiation
2. Rate of growth
3. Local invasion
4. Metastasis

The extent to which neoplastic tissues resemble their corresponding normal tissue of origin would affect the diagnosis of neoplasm. Being well differentiated and closely resembling the normal tissue of origin would mean it is less aggressive. The more anaplastic or undifferentiated it becomes, it becomes tougher to identify by morphology alone. It means it is more aggressive and severe.

1. Nuclear pleomorphism- variability in nuclear size/ shape
2. Abnormal nuclear features- high nuclear: cytoplasmic ratio, clumped chromatin, prominent nucleoli
3. increased mitotic activity
4. Loss of cellular polarity/ order
5. Tumour giant cells
6. Necrosis

Benign tumours are well differentiated and closely resemblance tissue origin. Malignant tumours have anaplastic features and generally poorer differentiation.

Metastatic potential is the ability to metastasise or spread to other sites within the tissues.

In the epithelium, malignancy goes beyond the basement membrane - invasion - Access to blood vessels, lymph nodes etc.

Neoplastic changes in the epithelium with the cytomorphological features of malignancy but confined within the basement membrane. It is seen as a precursor to malignancy because it hasn't yet reached the stroma, the point at which it would be considered malignant. There's architectural disruption and nuclear pleomorphism.

Dysplasia is seen as a precursor to the stage of malignancy but it doesn't always lead to it and it can regress.

Carcinoma in situ is defined as dysplasia of the entire epithelial layer without invasion of the basement membrane into the underlying tissue.

1. Cohesive and expansile masses
2. Localised
3. Don’t metastasise
4. Usually slow growth
5. May be encapsulated
6. Rim of compressed connective tissue= fibrous capsule

1. Invasive
2. Penetrate organ walls / tissues / epithelial surfaces
3. Next to metastases, invasiveness is the most reliable feature that differentiates malignant from benign tumours

The spread of tumour to a site discontinuous from the source organ / tissue

Reversible change from one mature cell type to another mature cell type

Tumours can be classified by benign/ malignant and in terms of the cell of origin.

Epithelial tumours can be classified in terms of the ectoderm, mesoderm and endoderm, and types of epithelial cells like squamous, cuboidal, columnar, glandular etc.

Adenoma (glands may or may not be present in the tumour)

Papilloma (finger like warty projections)

Thyroid adenoma

Squamous cell papilloma

Tissue or cell of origin and suffix 'oma'

Leiomyoma

Rhabdomyoma

Lipoma

Haemangioma

Osteoma

Chondroma

Fibroma

Carcinoma

Adenocarcinoma

Carcinoma with prefix of cell of origin

Squamous cell epithelium

Colonic adenocarcinoma

Sarcoma with a prefix of cell of origin

Leiomyosarcoma

Rhabdomyosarcoma

Liposarcoma

Angiosarcoma

Osteosarcoma

Chondrosarcoma

Fibrosarcoma

Teratomas originate from the gonads and contain cells representing all three germ cell layers- ectoderm, mesoderm and endoderm. Benign teratomas involve the formation of teeth, hair, muscle, neural tissue and cartilage. Malignant teratoma tissues are more primitive.

Precursor cell tumours bear histological resemblance to embryological in which it arises- Retinoblastoma, Nephroblastoma and Hepatoblastoma. It often occurs in young patients. It has a suffix of 'blastoma' because it is derivative of the embryological tissue.

A mixed tumour is a neoplasia in both the epithelial and mesenchymal tissue. A single clone may branch off into both types of tissues.

Carcinosarcoma; from epithelial and mesenchymal word roots

1. Glioblastoma multiforme
2. Astrocytoma
3. Meningioma
4. Neurinoma
5. Ependymoma
6. Oligoendroglioma
7. Medulloblastoma

Hamartoma is a non neoplastic disordered overgrowth of normal tissue which has developmental abnormalities.

Hamartoma is indigenous to the site of occurrence and is made of the same tissue that it is home to. e.g. a birthmark on the skin.

Choristoma is a rare benign tumour consisting of microscopically normal tissue derived from germ cell layers foreign to that body site.

Choristoma occurs in an abnormal location thus it is not indigenous to the site of occurrence. Example- Normal non neoplastic pancreatic nodule in the duodenum/ stomach.

1. Lymphoma
2. Myeloma
3. Leukaemia

It is a malignancy of B or T cell origin, often beginning in lymph nodes, but can also be extra nodal. There are different types of lymphomas like Hodgkins/ Non Hodgkins and B/T cell lymphoma.

Malignancy of plasma cells

Malignancy of white blood cells which begins in the bone marrow.

1. Melanoma
2. Melanocytic naevus

It is a malignancy of melanocytes- which are the cells that produce pigment in the skin.

Benign proliferation of melanocytes

1. Based on histological appearance (papillary carcinoma of the thyroid- finger like projections)
2. Genetic alterations- rhabdomyosarcoma with TFCP2 arrangement
3. Mixed elements with more than one type of malignant cell- ameloblastic fibrosarcoma, teratocarcinosarcoma.
4. Eponymous tumour- derived from the researcher's name like Warthin tumour, Kaposi sarcoma. The eponymous names have become more synonymous than the technical names so it is used.