Table 1

The 1999 World Health Organization/International Association for the Study of Lung Cancer Histological Classification of Lung and Pleural Tumours

1 Epithelial Tumours
 1.1. Benign
  1.1.1. Papillomas Squamous cell papilloma
    Inverted Glandular papilloma Mixed squamous cell and glandular papilloma
  1.1.2. Adénomas Alveolar adenoma Papillary adenoma Adenomas of salivary-gland type
    Mucous gland adenoma
    Pleomorphic adenoma
    Others Mucinous cystadenoma Others
 1.2. Preinvasive lesions
  1.2.1. Squamous dysplasia/Carcinoma in situ
  1.2.2. Atypical adenomatous hyperplasia
  1.2.3. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia
 1.3. Malignant
  1.3.1. Squamous cell carcinoma
   Variants Papillary Clear cell Small cell Basaloid
  1.3.2. Small cell carcinoma
   Variant Combined small cell carcinoma
  1.3.3. Adénocarcinoma Acinar Papillary Bronchioloalveolar carcinoma Non-mucinous (Clara/pneumocyte type II) Mucinous Mixed mucinous and non-mucinous
     or intermediate cell type Solid adenocarcinoma with mucin Adenocarcinoma with mixed subtypes Variants Well-differentiated fetal adenocarcinoma Mucinous (“colloid”) adenocarcinoma Mucinous cystadenocarcinoma Signet-ring adenocarcinoma Clear cell adernocarcinoma
  1.3.4. Large cell carcinoma
   Variants Large cell neuroendocrine carcinoma Combined large cell neuroendocrine carcinoma Basaloid carcinoma Lymphoepithelioma-like carcinoma Clear cell carcinoma Large cell carcinoma with rhabdoid phenotype
  1.3.5. Adenosquamous carcinoma
  1.3.6. Carcinomas with pleomorphic, sarcomatoid or sarcomatous elements Carcinomas with spindle and/or giant cells Pleomorphic carcinoma Spindle cell carcinoma Giant cell carcinoma Carcinosarcoma Pulmonary blastoma Others
  1.3.7. Carcinoid tumour Typical carcinoid Atypical carcinoid
  1.3.8. Carcinomas of salivary-gland type Mucoepidermoid carcinoma Adenoid cystic carcinoma Others
  1.3.9. Unclassified carcinoma
2 Soft Tissue Tumours
 2.1 Localized fibrous tumour
 2.2 Epithelioid hemangioendothelioma
 2.3 Pleuropulmonary blastoma
 2.4 Chondroma
 2.5 Calcifying fibrous pseudotumour of the pleura
 2.6 Congenital peribronchial myofibroblastic tumour
 2.7 Diffuse pulmonary lymphangiomatosis
 2.8 Desmoplastic small round cell tumour
 2.9 Other
3 Mesothelial Tumours
 3.1 Benign
  3.1.1 Adenomatoid tumour
 3.2 Malignant
  3.2.1 Epithelioid mesothelioma
  3.2.2 Sarcomatoid mesothelioma Desmoplastic mesothelioma
  3.2.3 Biphasic mesothelioma
  3.2.4 Other
4 Miscellaneous Tumours
 4.1 Hamartoma
 4.2 Sclerosing hemangioma
 4.3 Clear cell tumour
 4.4 Germ cell neoplasms
  4.4.1 Teratoma, mature or immature
  4.4.2 Malignant germ cell tumour
 4.5 Thymona
 4.6 Melanoma
 4.7 Others
5 Lymphoproliferative Disease
 5.1 Lymphoid interstitial pneumonia
 5.2 Nodular lymphoid hyperplasia
 5.3 Low-grade marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue
 5.4 Lymphomatoid granulomatosis
6 Secondary Tumours
7 Unclassified Tumours
8 Tumour-like Lesions
 8.1 Tumourlet
 8.2 Multiple meningothelioid nodules
 8.3 Langerhans cell histiocytosis
 8.4 Inflammatory pseudotumour (Inflammatory myofibroblastic tumour)
 8.5 Organizing pneumonia
 8.6 Amyloid tumour
 8.7 Hyalinizing granuloma
 8.8 Lymphangioleiomyomatosis
 8.9 Multifocal micronodular pneumocyte hyperplasia
 8.10 Endometriosis
 8.11 Bronchial inflammatory polyp
 8.12 Others