Australian Society of CytologyCase of the Month
August 2004
Small cell undifferentiated carcinoma - lung primary.
Answer
Cytology
Closely packed small cells with scanty cytoplasm. (fig1)
Hyperchromatic and moulded nuclei with irregular outlines are noted.
Single “indian” file arrangements present. Some cellular degeneration is seen. (figs 2,3,4)
Chromatin is coarse and stippled with inconspicuous nucleoli.
Highly suspicious of small cell undifferentiated carcinoma.
Histology
Irregular pleomorphic cells arranged in sheets (fig5) and showing widespread necrosis. (fig6)
Small cell undifferentiated carcinoma - lung primary.
) |
) |
) |
| fig 5 | fig 6 | fig 7 |
Discussion
Small cell carcinoma is a neuroendocrine tumour, usually growing in the central bronchi or in a hilar position and accounts for up to 25% of all primary lung tumours.
The tumour has a rapid, aggressive growth pattern, will metastisize to distant sites and has a poor prognosis.
Cytologically, the appearance of small cell ca’ can be dependant on the type of sample taken. Bronchial brushings and FNA specimens tend to show better preservation of tumour cells than in sputum and bronchial washings where degenerative changes are common.
Thus, tumour cells show larger nuclei with a more open chromatin pattern and small nucleoli are visible in brushings/FNA smears.
However, in all types of specimen (particularly in brushing specimens), traumatic crush artefact gives the tumour cells a characteristic smudged appearance highlighting the fragility of the nuclei. A feature rarely seen in other lung tumours.
Specific immunocytochemical (neuroendocrine) markers for small cell ca’ are Chromogranin A and Synaptophysin which are demonstrated in the cytoplasm of the tumour cells.
Electron microscopy will show cytoplasmic neuroendocrine granules ultrastructurally. (fig7)
References:
- Gray W,McKee G, Diagnostic Cytopathology, 2nd Edition,Churchill Livingstone 2003.
- Geisinger K,Raab S,Stanley M,Silverman J,Abati A, Modern Cytopathology, Churchill Livingstone 2004.
- Demay R, Practical principles of Cytopathology, ASCP Press 1999.
- Cibas E, Ducatman B, Cytology, Diagnostic principles and clinical correlates, 2nd Edition, Elsevier 1996.
