Classification of Diseases

In this section we discuss the various ways lung cancer has been classified. The two most important classifications are the histological and the TNM staging classifications. The histopathological classifications divide the disease into two fundamental groups as we discussed in above in the sttrucural principles section; small cell and non small cell carcinomas. This distinction is important in the approach to the management and prognostication of the disease.

The staging classification divides the disease into groups based on size of tumor, extent of adenopathy, and systemic extent of disease.
Other classifications that are helpful include the functional status of the patient in considering surgery, and the radiological classifications of lung tumor based on morphology.

Histopathology

 

Histological Types

Normal

 

Small Cell

 

Squamous Cell

 

Adenocarcinoma

Adenocarcinoma with Lepidic Growth

 

Large Cell

Histological Types	% Total
Squamous Cell	29%
Small Cell	20%
Large Cell Carcinoma	9%
Large Cell Neuroendocrine	2%
Adenocarcinoma a)      acinar b)      papillary c)      bronchioalveolar d)      mucus secreting	32%
Adenocarcinoma with Lepidic Growth (Bronchioloalveolar)	3%
Others	12%

 

 Preinvasive lesions include;

Squamous dysplasia/carcinoma in situ

Atypical adenomatous hyperplasia

Diffuse idiopathic pulmonary neuroendocrine hyperplasia

Gross Pathology

Carcinoma of the lung most commonly presents as a mass and less commonly as an alveolar process which is the mode of presentation for the bronchioloalveolar type. However because it originates in a tubular system and because of its infiltrative nature the macroscopic picture will depend on the presence or absence of atelectasis, localized emphysema, associated pneumonia, lymphangitis, pleural involvement and pericardial involvement

Size

Malignant tumors range in size from a few mms to up to 10 or even 15 cms.
Large cell carcinoma is usually large, bulky, and well circumscribed.

Shape

The tumors themselves are mostly nodular or round or irregularly shaped, except for alveolar cell which may look like a segmental pneumonia. Bronchioalveolar carcinoma may also take the form of a single nodule or more often, as multiple diffuse nodules that coalesce to produce a pneumonia-like consolidation.

Suspicious Spiculated Nodule

46361b01 Copyright 2010 Courtesy Ashley Davidoff MD

Position

Squamous and small cell carcinomas tend to be central while adenocarcinomas including alveolar carcinomas tend to be peripheral, often near a pleural surface. The pleural surface is often pinched over the tumor. Squamous cell carcinoma also tends to be found more commonly in the upper bronchi.

Character

Adenocarcinoma is usually hard to the feel with a white or grey and glistening matrix.
Squamous cell carcinoma usually presents as a well circumscribed, rubbery mass appearing as a gray-white and dry matrix, often associated with hemorrhage, necrosis, and cavitation. (10-20%) (32202c)
Large cell carcinoma is usually a well delineated bulky tumor with a pink gray cut surface often complicated by hemorrhage and necrosis.
Bronchioloalveolar carcinoma, may present as a mucinous mass, as diffuse multinodular lesion, or as a infiltrate.

 

Links and References

• TCV
  • Cancer Map
  • Cancer Cases
  • Smoking Related Diseases Map