Bronchogenic carcinoma is the most common type of the lung tumors.

Bronchogenic carcinoma is the most common type of tumor causing death in both men and women.

The etiologic factors include smoking, exposure to radiation, asbestos, radon exposure, exposure to the occupational inhaled substances such as nickel, chromates, arsenic, and genetic factors.

The incidence of the bronchogenic carcinoma is clearly higher in smokers and is related to the pack-year smoking.

Bronchogenic carcinoma may present with cough, weight loss, shortness of breath, chest pain which may be caused by the destruction of the rib, lipid penumonia, pneumonia or abscess due to the obstruction of airways, dysphagia due to invasion of the esophagus, hoarsness due to the involvement of the laryngeal nerve, paralysis of the diaphragm due to the invasion of the phrenic nerve, Horner's syndrome due to the invasion of the sympathetic ganglia, superior vena cava syndrome due to the obstruction of the superior vena cava, pleural effusion, pericardial effusion and release of hormones. Ectopic production of hromones is responsible for the paraneoplastic syndrome such as Cushing's syndrome (ACTH), hypercalcemia (parathormone or PGE), hpocalcemia (calcitonin), gynecomastia (gonadotropins), carcinoid syndrome (serotonin), acanthosis nigricans, peripheral neuropathy, myopathy, and hypertrophic pulmonary osteoarthropathy such as clubbing of the fingers.

Bronchogenic carcinoma is classified according to the cell lineage of the tumor as follows:

TYPE	SUBTYPE
SQUAMOUS CELL CARCINOMA
ADENOCARCINOMA
	Bronchial (acinar, papillary, solid)
	Bronchioalveolar
SMALL CELL CARCINOMA
	Oat cell type
	Intermediate cell type
	Combined (commonly squamous) type
LARGE CELL CARCINOMA (UNDIFFERENTIATED)
COMBINED ADENOCARCINOMA-SQUAMOUS CELL CARCINOMA (ADENOSQUAMOUS)

Squamous cell carcinoma. This tumor usually arises from the bronchus near the hilus. Is more common in males and shows squamous differentiation of various degress.

Adenocarcinoma. This tumor usually arises in the periphery. Is the most common lung cancer in women, and shows evidence of glandular differentiation of various degrees.

Small cell carcinoma: This tumor usually arises close to the hilum. Is the most malignant lung cancer and is composed of oat cells which are smaller than tumor cells found in the squamous cell carcinoma and adenocarcinoma. The tumor cells have little cytoplasm, are arranged in clusters and nests, show arefactual smearing after processing, do not show evidence of squamous or glandular differentiation and have neurosecretory granules. The neurosecretory granules may be identified at the ultrastructural level or by immunohistochemical demonstration of chromogranin or synaptophysin. This is the type of the tumor that is associated with paraneoplastic syndromes.