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Monday, January 17, 2011

Histology and Classification of Tumors


Neoplasia (tumors) are abnormal tissue proliferations, which develop exceeding normal tissue, uncoordinated with it. This uncontrolled tissue growing may continue even after cessation of the etiologic factor (self-maintained). The structure of a tumor (neoplasia) : parenchyma (tumor cells derived from previously normal cells) and stroma (vessels and connective tissue), in variable proportions.



Classification and nomenclature of tumors

Tumours composed of one parenchymal cell type Benign Malignant
1. Epithelial tumours
Stratified squamous epithelium Squamous cell papilloma Squamous cell carcinoma
Basal cells of skin or adnexa Seborrheic keratosis Basal cell carcinoma
Glands or ducts
  • Adenoma (adenomatous polyp)

  • Cystadenoma
  • Adenocarcinoma
  • Papillary carcinoma
  • Cystadenocarcinoma
Respiratory tract epithelium
Bronchogenic carcinoma
Neuroectoderm Melanocytic nevus Malignant melanoma
Renal epithelium Renal tubular adenoma Renal cell carcinoma
Liver cells Liver cell adenoma Hepatocellular carcinoma
Bile ducts Billiary adenoma Bile duct carcinoma
Urinary tract epithelium (transitional) Transitional cell papilloma Transitional cell carcinoma
Placental epithelium - gestational trophoblast Hydatidiform mole Gestational choriocarcinoma
2. Mesenchymal tumours
Conjunctive tissue and derivatives :
  • fibroblasts
  • lipoblasts
  • chondroblasts
  • osteoblast

  • Fibroma
  • Lipoma
  • Chondroma
  • Osteoma

  • Fibrosarcoma
  • Liposarcoma
  • Chondrosarcoma
  • Osteogenic sarcoma
Endothelium and relative tissues :
  • blood vessels
  • lymphatic vessels
  • synovia
  • mesotelium

  • meninge

  • Hemangioma
  • Lymphangioma

  • Solitary fibrous tumour of the pleura
  • Meningioma

  • Angiosarcoma
  • Lymphangiosarcoma
  • Synoviosarcoma
  • Malignant mesothelioma

  • Invazive meningioma
Blood cells :
  • hematopoietic cells
  • lymphoid tissue


  • Leukemias
  • Malignant lymphomas (Hodgkin's and non-Hodgkin's lymphomas)
Muscle fibers :
  • smooth
  • striated

  • Leiomyoma
  • Rhabdomyoma

  • Leiomyosarcoma
  • Rhabdomyosarcoma

Tumours with different types of cells from the same germ layer - mixed tumours Benign Malignant
Salivary glands Pleomorphic adenoma (Mixed tumour of salivary gland origin) Malignant mixt tumour of salivary gland origin
Breast Fibroadenoma Malignant cystosarcoma phyllodes
Nephroblastem (metanephric blastema)
Nephroblastoma (Wilms' tumor)

Tumours with different types of cells derived from more than one germ layer - teratogenous Benign Malignant
Totipotential cells in gonads or in embryonic rests
  • Mature teratoma
  • Dermoid cyst
  • Immature teratoma
  • Teratocarcinoma (Embryonic carcinoma)
  • Endodermal sinus tumour
  • Non-gestational choriocarcinoma

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