Neoplasm :

 Introduction :

• Neoplasia = new growth ( abnormal and excessive growth )
• Study of neoplasm (tumor) = oncology
• Neoplasm is the new and abnormal growth of tissue in a part of the body , especially as a characteristic of cancer.
• It is a self controlling growth formed by unlimited multiplication of abnormal cells.

Classification :

The classification is done under following basis :

a. Behaviour of tumor ( benign or malignant )

i. Benign : epithelial

•              Mesenchymal

ii. Malignant : primary

•                  Epithelial ( carcinoma )
•                  Mesenchymal ( sarcoma)

b. On the based on anatomical site

i. Histological analysis ( grading )

ii. Extent of disease :  classification ( staging )

iii. TNM ( tumor , node, metastasis )

Behaviour of tumor

A. Benign tumor : ( pathology)

I. Gross finding :

• Size : usually small in size
• Shape : usually ovoid or rounded in shape
• Capsule : usually encapsulated
• Cut section solid or cystic
• Haemorrhages and necrosis are usually absent .

II.   Microscopic: 

• Differentiation : the cells are well differentiated i.e. tumor cells closely similar to tissue of origin .
• Nucleocytoplasmic ratio ( N/C ) : small / normal
• Stroma : is usually well formed with few blood vessels.

  III. Behaviour :

• Rate of growth : usually slow
• Mode of growth : expansion
• Localization : usually localized
• Effects on host : usually do not destroy surrounding structures and don’t kill the patient (except in certain sites as in brain )
• Recurrence : usually not recurrent
• Metastasis : don’t metastasis ( development of secondary growth at a distance from a primary site of tomor )
• Malignant change : may occur

        Nomenclature :

• Benign tumor : prefix + suffix

                       Type of cell + ( oma )

• Benign tumor arising in fibrous tissue = fibroma
• Benign tumor arising in fatty tissue = lipoma

• Benign epithelial tumors : Papilloma

                                       Adenoma ( benign epithelial neoplasms producing gland pattern )

• Mesenchymal tumors :

1. CT tumors :

• Fibroma
• Lipoma
• Chondroma
• Osteoma

2. Muscle tumors :

• Leiomyoma ( also known as fibroids, is a benign smooth muscle tumor that very rarely becomes cancer (0.1%))
• Rhabdomyoma ( is a benign tumor of striated muscle)

3. Vessels :

• Haemangioma ( is a usually benign vascular tumor derived from blood vessel cell types.)
• Lymphangioma ( are malformations of the lymphatic system characterized by lesions that are thin-walled cysts; these cysts can be macroscopic, as in a cystic hygroma)

B. Malignant tumors :

• Have two basic component :

1. Parenchyma :

• Made up of neoplastic cells
• Determines the biological behaviour of the tumor from which the tumor derives its name .

1. Stroma :

• Made up of non-neoplastic cells, host derived CT and blood vessels

Malignant tumor arising in mesenchymal tissue (  multipotent stem cells found in bone marrow that are important for making and repairing skeletal tissues, such as cartilage, bone and the fat found in bone marrow.)    

Sarcoma

• Fibrous tissue : Fibrosarcoma
• Bone : Osteosarcoma
• Cartilage : chondrosarcoma

Malignant tissue arising from epithelial origin : Carcinoma

• Squamous cell carcinoma
• Renal cell adenocarcinoma
• Cholangiocarcinoma ( bile duct cancer )

Nomenclature of some malignant tumors with exception :

• Melanoma ( skin)
• Mesothelioma ( mesothelium )
• Seminoma ( testis)
• Lymphoma ( lymphoid tissue )

Pathology :

a. Gross lesions :

• Size : usually reach large size
• Shape :
• Polypoid of fungating mass in tumors of solid organs .
• Malignant ulcer in tumor of surface epithelium
• Infiltrating annular mass in tumor of hollow organs
• Capsule : non- capsul;ated
• Cut section solid / cystic
• Haemorrhage and necrosis : common

b. Microscopic pathology :

• Differentiation : the cells dhow loss of differentiation
• The cells show some or all features of mal;ignancy as loss of polarity of cells, hyperchromatic nuclei , increase N/C ratio , abnormal mitosis and prominent nucleolus
• Stroma : usually desmoplastic with rich vascularity

Behaviour :

• Rate of growth : usually rapid
• Mode of growth : by infiltration
• Localization : usually not localized
• Effect on host : can kill the patient whenever present
• Recurrence : may occur
• Metastasis : may occur

 Precancerous lesions :

• Chronic inflammatory lesions
• Hyperplastic lesions
• Some benign tumors
• Other lesions as peptic ulcer and undescribed testis.

Spread of  malignant tumors :

a. Mechanism of spread

• Invasion of matrix
• Vascular dissemination and homing of tumor cells

b. Route of spread :

i. Direct / local spread

   Malignant cells infiltrate the surrounding structures in all direction

ii. Distant spread :

• Lymphatic spread
• Lymphatic permeation
• Lymphatic embolization
• Blood spread
• Course of tumor emboli
• Organ metastasis
• Transcoelomic spread
• Spread by implantation

2. Anatomical; site :

3. Histological analytic :

  It defines the types of tissue from which tumor is originated :

• Grade I : cells are slightly differed from normal cells and well differentiated
• Grade II : cells are more abnormal and moderately differentiated.
• Grade III : cells are abnormal and poorly differentiated
• Grade IV : cells are immediate and primitive and undifferentiated

Staging : progression or spread in body

Grading : cell differentiation and rate of growth – microscopy

4. Extent of disease :

• Stage 0 : cancer in situ (cell)
• Stage I : tumor linked to tissue origin , localized tumor growth
• Stage II : limited local spread
• Stage III : extensive local and regional spread
• Stage IV : metastasis

5. TNM classification :

• This system represent clinical staging of cancer
• Used to determine the extent of disease process of cancers according to three parameters:
• Tumor size ( T)
• Degree of regional spread to LN ( N)
• Presence of metastasis (M)
• It has been used in diagnosing breast cancer .

Etiology :

A. Benign tumors :

• Often the cause is unknown
• But the growth might be linked to :
• Environmental toxins such as exposure to radiation
• Genetics
• Diet
• Stress
• Local trauma or injury
• Inflammation or infection

B. Malignant tumors :

a. Precancerous lesions :

   Some lesions that exhibit a tendency to undergo malignant transformation

• Endometrial hyperplasia – endometrial carcinoma
• Liver cirrhosis – hepatocellular carcinoma
• Squamous metaplasia lead to squamous cell carcinoma
• Benign tumors :
• Papilloma of urinary bladder
• Adenoma of thyroid or colon

b. Helping factors ( carcinogens)

• Age
• Sex
• Diet : fat – colonic cancer
• Smoked fish – gastric carcinoma
• Smoke : lung cancer
• Heredity : retinoblastoma

c. Carcinogens :

• Chemical carcinogens
• Viruses
• Radiation

    Mode of growth :

a. Benign tumors :                              

• Remain localized
• Grow by expansion with available space or by compression of tissues
• Cause adverse effects if near vital structure

b. Malignant tumors :

• Do not remain localised
• Local growth is by infiltration and super population of adjacent of tissues
• Invasion causes destruction of local normal tissues.

Development / pathophysiology :

  Carcinogens are substances that when introduced into cells cause changes in structure and function of cells and lead to cancer , however it occurs in several stages over a period of time .

• Three identified status :

1. Initiation
2. Promotion
3. Progression

• Initiation

Causative agents ( carcinogens)                          

              ⬇

                        Target cell

              ⬇

                          Altered

              ⬇

                          Cancer

• Promotion

                   ⬇

Proliferation at mitotic rate at tissue of organ  

• Progression

                    ⬇

Evidence of clinical disease

              ⬇

Evidence of regional spread and metastasis

Diagnosis :

• Morphological methods :
• History
• Clinical sign
• Biochemical assay : useful for measuring the levels of tumor associated with enzymes , hormones , tumors markers in serum
• Biopsy
• Radiograph
• Molecular diagnosis : PCR , FISH ( Fluorescent in situ Hybridization )