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Friday, February 3, 2012

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 typeBenignMalignant
1. Epithelial tumours
Stratified squamousepitheliumSquamous cellpapillomaSquamous cell carcinoma
Basal cells of skin or adnexaSeborrheic keratosisBasal cell carcinoma
Glands or ducts
  • Adenoma (adenomatous polyp)

  • Cystadenoma
  • Adenocarcinoma
  • Papillary carcinoma
  • Cystadenocarcinoma
Respiratory tractepithelium
Bronchogenic carcinoma
NeuroectodermMelanocytic nevusMalignant melanoma
Renal epitheliumRenal tubular adenomaRenal cell carcinoma
Liver cellsLiver cell adenomaHepatocellularcarcinoma
Bile ductsBilliary adenomaBile duct carcinoma
Urinary tract epithelium (transitional)Transitional cell papillomaTransitional cellcarcinoma
Placental epithelium - gestational trophoblastHydatidiform moleGestational 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 tumoursBenignMalignant
Salivary glandsPleomorphic adenoma (Mixed tumour ofsalivary gland origin)Malignant mixt tumour ofsalivary glandorigin
BreastFibroadenomaMalignant cystosarcoma phyllodes
Nephroblastem (metanephric blastema)
Nephroblastoma (Wilms' tumor)

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

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