MALIGNANT TUMORS OF EPITHELIAL TISSUE

Posted by DAM on February 2, 2012 | Short Link
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MALIGNANT TUMORS OF EPITHELIAL TISSUE

 

 

Carcinoma:

It is a malignant tumor arising from epithelial tissue and is the commonest type of all malignant tumors.

Features of carcinoma:

  1. Age: commonly above 40 years.
  2. Rate of growth: variable but generally less than sarcoma
    1. Consistency: it is usually hard, but few are soft as medullary carciroma and mucoid carcinoma.
    2. The cut section: it is grayish white and may show necrosis and hemorrhage. It usually cuts with a gritty sensation due to increased amount of dense collagenous stroma.
    3. Spread: carcinoma spreads early by lymphatics and later by blood.
  3. Pathology.

 

A. Naked eye or gross appearance:

It starts as a small nodule in the epithelium which grows and infiltrates the underlying tissue and then takes one of the following appearances:

  1. Fungating or polypoid carcinoma: This forms a large outward growth with an infiltrating base.
  2. Infiltrating carcinoma: in which the malignant tissue infiltrates more in to the deeper structures.

 

3- Ulcerative carcinoma: malignant ulcer: It appears as a large ulcer with hard infiltrating base, and raised, indurated and everted edges and a floor showing necrotic material.

Microscopic types of carcinoma or classification of carcinoma:

I – Carcinoma arising from surface epithelium:

a- Squamous cell carcinoma, b- Basal cell carcinoma, c- Transitional cell carcinoma, d- Carcinoma in situ or intra-epithelial carcinoma. II- Carcinoma arising from glandular epithelium:

a- Adenocarcinoma.

b- Mucoid carcinoma.

A) Carcimoma arising from surface epithelium: I- Squamous cells carcinoma:

  • It is a very common malignant tumor which arises from prickle cell layer of the stratified squamous epithelium all over the body such as skin, lips, tongue, and oesophagus.
  • Gross appearance: it starts as a small nodule in the epithelium which grows and infiltrates the underlying tissues and takes one of the following appearances:

 

  1. Fungating or polypoid carcinoma.
  2. Infiltrating carcinoma.
    1. Ulcerative carcinoma or (malignant ulcer): it is the commonest type which either arises as such from the beginning or develops on tope of one of the above two types.

 

- Microscopic appearance:

  1. There is infiltration by large polygonal cells arranged in solid masses of variable size and shape which are separated by dense fibrous tissue.
  2. The malignant cells have abundant pinkish cytoplasm and large darkly stained nuclei having one or more well apparent pinkish nucleoli.
  3. In some of these masses, the cells in the central area are replaced by structureless lamellae of keratin stained bright red with eosin. This occurs in the differentiated group and is called cell nest appearance or keratinization or epithelial pearl.

The degree of differentiation of squamous cell carcinoma depends on the number of groups with the cell nest appearance (Broder’s classification):

Grade I: contains more than 75% differentiated or keratinized groups i.e. well differentiated squamous cell carcinoma.

Grade II: contains 50-75% differentiated or keratinized groups i.e. moderately differentiated squamous cell carcinoma.

Grade III: contains 25-50% differentiated or keratinized groups i.e. poorly differentiated.

Grade IV: contains less than 25% differentiated or keratinized group i.e. undifferentiated squamouns cell carcinoma.

II- Basal cell carcinoma or rodent ulcer or basal cell epithelioma:

- It is a common locally malignant tumor arising from the basal cells of the skin of areas exposed to the sunshine, particularly the face and neck. On the face, it usually arises from the skin above a line drawn from the angle of the mouth to the lobule of the ear.

A- Gross appearance:

1 – It arises as a small nodule, very gradually increases in size and soon ulcerates, forming an irregular ulcer with eroded edges and hence the name (rodent ulcer).

  1. Secondary pyogenic infection is common. It does not metastasize but it may infiltrate extensively into the underlying structures such as bones.
  2. Enlargement of the draining lymph nodes with rodent ulcer, is usually due to an accompanying lymphadenitis due to secondary infection and not due to metastasis because the basal cell carcinoma is a locally malignant tumor.

B- Microscopic appearance:

The dermis is infiltrated by masses of small polygonal darkly stained cells having large oval nuclei. The peripheral layer of cells in each mass are placed near to each other in a palisade manner, no cell nests are seen.

The skin is ulcerated and there is secondary infection.

  1. Transitional cell carcinoma: occurs mainly in the urinary bladder.
  2. Intraepithelial carcinoma (carcinoma in situ or pre-invasive carcinoma):

It is the early malignant change which appears in epithelial cells before basement membrane is infiltrated. The cells become irregularly arranged with loss of polarity and nuclei become large, hyperchromatic and show mitotic figures.

The commonest sites are:

  1. Cervix uteri.
  2. Skin.
  3. Bronchial epithelium.
  4. Buccal mucosa.

Its detection is useful and important for early treatment.

B- Carcinoma arising from glandular epithelium:

1-    Adenocarcinoma.

2-    Mucoid carcinoma.
Adenocarcinoma:

  • It is a differentiated malignant tumor of glandular tissues, in which the malignant cells are arranged in acinar formations.
  • Sites: the commonest site is G.I.T (stomach, colon, and rectum).
  • Gross appearance: as the tumor grows and infiltrates the surrounding tissues, it takes one of the following appearances:

 

  1. Ulcerative carcinoma, (the commonest)
  2. Infiltrating carcinoma.
  3. Fungating carcinoma.

-    Microscopic appearance: There is infiltration by malignant cells arranged in glandular or acinar formations. These are irregular in size and shape. They are lined by one or more layers of columnar or rounded cells having large darkly stained nuclei with many mitotic figures

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