pulmonary squamous cell carcinoma

Digital case

 JRC:1602 : Pulmonary squamous cell carcinoma (variable differentiation).
 JRC:6204 : Pulmonary squamous cell carcinoma (with in situ component).
 JRC:6208 : Pulmonary squamous cell carcinoma.
 JRC:6213 : Peripheral pulmonary squamous cell carcinoma (with tuberculosis).
 JRC:6217 : Pulmonary squamous cell carcinoma.
 JRC:6218 : Pulmonary well differentiated 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

Macroscopy

 cavitating pulmonary squamous cell carcinoma

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

Overexpression/Amplification

 FGFR1 is frequently overexpressed in squamous cell carcinoma and adenocarcinoma of the lung. (18829480)

• bFGF signaling pathway activation may be an early phenomenon in the pathogenesis of squamous cell carcinoma and thus an attractive novel target for lung cancer chemopreventive and therapeutic strategies. (18829480)

 high- and low-level FGFR1 amplification types in squamous cell lung cancer. (22684217)

• fibroblast growth factor receptor-type 1 (FGFR1) amplification is associated with therapeutically tractable FGFR1 dependency in squamous cell lung cancer.
• FGFR1 is a target for directed therapy in these tumors.
• FGFR1 amplification is one of the most frequent therapeutically tractable genetic lesions in pulmonary carcinomas.
• Standardized reporting of FGFR1 amplification in squamous carcinomas of the lung will become increasingly important to correlate therapeutic responses with FGFR1 inhibitors in clinical studies. (22684217)

Types

 pseudovascular adenoid squamous cell carcinoma of the lung (8163270)

Videos

 Pulmonary squamous cell carcinoma by Washington Deceit

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See also

 pulmonary tumors

• pulmonary carcinomas

Books

 IARCC. WHO 2004

References

 Definition of a fluorescence in-situ hybridization score identifies high- and low-level FGFR1 amplification types in squamous cell lung cancer. Schildhaus HU, Heukamp LC, Merkelbach-Bruse S, Riesner K, Schmitz K, Binot E, Paggen E, Albus K, Schulte W, Ko YD, Schlesinger A, Ansén S, Engel-Riedel W, Brockmann M, Serke M, Gerigk U, Huss S, Göke F, Perner S, Hekmat K, Frank KF, Reiser M, Schnell R, Bos M, Mattonet C, Sos M, Stoelben E, Wolf J, Zander T, Buettner R. Mod Pathol. 2012 Jun 8. PMID: 22684217