The Clinical Relevance of Recent Developments in Pathology and Biology of Small Cell Lung Cancer: Immunohistochemistry

In: Lung Cancer

14 Nov 2014

It has been known for decades that SCLC has a great potential for producing multiple endocrine “markers.” Following the rapid development in immunocytochemistry and monoclonal antibodies during the past decade, much interest has been devoted to a variety of malignant lung tumors including SCLC. The studies have particularly concentrated on the following subjects: (A) general neuroendocrine markers, (B) specific peptides, and (C) more unspecific small cell antigens detected by monoclonal antibodies. The purpose of the studies has been to achieve more information about the biology of the tumors, the interrelationship between the different histologic types, and to reveal whether various antibodies can be used to improve the histopathologic classification. fully

Immunohistochemical Characteristics of SCCL and their Relationship to other Malignant Lung Tumors
Various studies using continuous cell lines have revealed that SCLC produces a number of hormones and hormonelike substances, which can be demonstrated by “traditional” immunocytochemical techniques such as immunoperoxidase staining.
A. Common neuroendocrine markers: Among the most interesting neuroendocrine markers studied by immunohistochemistry in SCLC are: neuron-specific enolase (NSE), chromogranin A, neurotensin, synaptophysin, and protein gene product 9,5 (PGP 9,5).
In order to find a specific diagnostic marker considerable interest has been attached to NSE. While most studies have identified NSE in almost all SCLC-tumors (70-100%), several studies have also demonstrated NSE in a variable fraction of non-SCLC tumors (15-55%). Chromogranin was suggested to be a promising neuroendocrine marker by Wilson and Lloyd, and it was demonstrated in 4/10 SCLC tumors. Others have not been able to reproduce the high frequency of expression of chromogranin in SCLC. In a more recent study by Hirsch et al, chromogranin was demonstrated in 25% of the SCLC tumors and in 5% of non-SCLC tumors.
Another recently characterized neuroendocrine marker in SCLC is synaptophysin, which has been identified in 79% of 68 SCLC tumors, compared with 8% of 74 non-SCLC tumors. Future studies have to verify whether this is a useful SCLC-marker in the diagnosis of malignant lung tumors. A new antigen originally extracted from the brain and termed protein gene product 9,5 (PGP 9,5) has been observed by immunohistochemistry in both “oat-cell” and “intermediate” type SCLC and in a series of neural and endocrine tumors. The specificity in the diagnosis of malignant lung tumors has not yet been sufficiently studied on surgical human material.

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