pulmonary squamous cell carcinoma
Definition: Squamous cell carcinoma (SCC) is a malignant epithelial tumour showing keratinization and/or intercellular bridges that arises from bronchial epithelium.
Epidemiology - Etiology
Over 90% of squamous cell lung carcinomas occur in cigarette smokers. Arsenic is also strongly associated with squamous cell carcinoma.
Sites of involvement
The majority of squamous cell lung carcinomas arise centrally in the mainstem, lobar or segmental bronchi.
Imaging
Radiography
In central SCC, lobar or entire lung collapse may occur, with shift of the mediastinum to the ipsilateral side.
Central, segmental or subsegmental tumours can extend into regional lymph nodes and appear as hilar, perihilar or mediastinal masses with
or without lobar collapse.
Peripheral tumours present as solitary pulmonary nodules (< 3 cm) or masses (> 3 cm).
Squamous cell carcinoma is the most frequent cell type to cavitate
giving rise to thick walled, irregular cavities with areas of central lucency on the chest film.
When located in the superior sulcus of the lung, they are called Pancoast tumours and are frequently associated with destruction of posterior ribs and can cause Horner’s syndrome.
The chest radiograph may be normal in small tracheal or endobronchial tumours
1820.
Hilar opacities, atelectasis or peripheral masses may be associated
with pleural effusions, mediastinal enlargement or hemidiaphragmatic elevation.
CT and spiral CT
The primary tumour and its central extent of disease is usually
best demonstrated by CT scan.
Spiral CT may assess better the thoracic extension of the lesion, reveal small primary or secondary nodules invisible on chest radiograph, and exhibit lymphatic spread.
PET scan
This is now the method of choice to identify metastases (excluding
brain metastases which may require MRI). Bone metastases are typically osteolytic.
Cytology
The cytologic manifestations of squamous cell carcinoma depend on the degree of histologic differentiation and the type of sampling. In a background of necrosis and cellular debris, large tumour cells display central, irregular hyperchromatic nuclei exhibiting one or more small nucleoli with an abundant cytoplasm.
Tumour cells are usually isolated and may show bizarre shapes such as spindle-shaped and tadpole-shaped cells. They may appear in cohesive aggregates, usually in flat sheets with elongated or spindle nuclei.
In well-differentiated squamous cell carcinoma keratinized cytoplasm appears robin’s egg blue with the Romanowsky stains, whereas with the Papanicolaou stain, it is orange or yellow.
In exfoliative samples, surface tumour cells predominate and present as individually dispersed cell with prominent cytoplasmic keratinization and dark pyknotic nuclei.
In contrast, in brushings, cells from deeper layers are sampled, showing a much greater proportion of cohesive aggregates.
ICD-O code
Squamous cell carcinoma 8070/3
- Papillary carcinoma 8052/3
- Clear cell carcinoma 8084/3
- Small cell carcinoma 8073/3
- Basaloid carcinoma 8083/3
Microscopy
A proliferation of malignant epithelial cells.
Cytoplasm of cells is eosinophilic suggesting keratin production and there is squamous "pearl" formation.
Cytologically the nuceli are pleomorphic (vary in size and shape) and hyperchromatic (increased chromatin, darker stained).
LOH
9p13 LOH
Types
pseudovascular adenoid squamous cell carcinoma of the lung (#8163270#)
Videos
Pulmonary squamous cell carcinoma by Washington Deceit
See also
pulmonary tumors
- pulmonary carcinomas
References