Page 250 - Textbook of Pathology, 6th Edition

234 7. Other Modern Aids in Pathologic
 TABLE 8.13: Intermediate Filaments and their Significance
in Tumour Diagnosis. Diagnosis of Tumours
Intermediate Tumour In addition to the methods described above, some other
Filament
modern diagnostic techniques have emerged for tumour
1. Keratins Carcinomas, mesotheliomas, diagnostic pathology but their availability as well as
some germ cells tumours
applicability are limited. These methods are discussed in
2. Vimentin Sarcomas, melanomas, Chapter 2. Briefly, their role in tumour diagnosis is outlined
lymphomas
below.
3. Desmin Myogenic tumours
SECTION I
i) Flow cytometry. This is a computerised technique by
4. Neurofilaments (NF) Neural tumours
which the detailed characteristics of individual tumour cells
5. Glial fibrillary Glial tumours
acidic protein (GFAP) are recognised and quantified and the data can be stored for
subsequent comparison too. Since for flow cytometry, single
cell suspensions are required to ‘flow’ through the
hormones and cancer antigens; these are listed in Table 8.14. ‘cytometer’, it can be employed on blood cells and their
However, two of the best known examples of oncofoetal precursors in bone marrow aspirates and body fluids, and
antigens secreted by foetal tissues as well as by tumours are sometimes on fresh-frozen unfixed tissue. The method
alpha-foetoproteins (AFP) and carcinoembryonic antigens employs either identification of cell surface antigen (e.g. in
(CEA): classification of leukaemias and lymphomas), or by the DNA
content analysis (e.g. aneuploidy in various cancers).
a) Alpha-foetoprotein (AFP): This is a glycoprotein
synthesised normally by foetal liver cells. Their serum levels ii) In situ hybridisation. This is a molecular technique by
are elevated in hepatocellular carcinoma and non- which nucleic acid sequences (cellular/viral DNA and RNA)
seminomatous germ cell tumours of the testis. Certain non- can be localised by specifically-labelled nucleic acid probe
neoplastic conditions also have increased serum levels of AFP directly in the intact cell (in situ) rather than by DNA
e.g. in hepatitis, cirrhosis, toxic liver injury and pregnancy. extraction (see below). A modification of in situ hybridisation
b) Carcino-embryonic antigen (CEA): CEA is also a technique is fluorescence in situ hybridisation (FISH) in which
glycoprotein normally synthesised in embryonic tissue of the fluorescence dyes applied and is used to detect
gut, pancreas and liver. Their serum levels are high in cancers microdeletions, subtelomere deletions and to look for
of the gastrointestinal tract, pancreas and breast. As in AFP, alterations in chromosomal numbers. In situ hybridisation
General Pathology and Basic Techniques
CEA levels are also elevated in certain non-neoplastic may be used for analysis of certain human tumours by the
conditions e.g. in ulcerative colitis, Crohn’s disease, hepatitis study of oncogenes aside from its use in diagnosis of viral
and chronic bronchitis. infection.

  TABLE 8.14: Important Tumour Markers.
Marker Cancer
1. ONCOFOETAL ANTIGENS:
i. Alpha-foetoprotein (AFP) Hepatocellular carcinoma, non-seminomatous germ cell tumours of testis
ii. Carcinoembryonic antigen (CEA) Cancer of bowel, pancreas, breast
2. ENZYMES:
i. Prostate acid phosphatase (PAP) Prostatic carcinoma
ii. Neuron-specific enolase (NSE) Neuroblastoma, oat cell carcinoma lung
iii. Lactic dehydrogenase (LDH) Lymphoma, Ewing’s sarcoma
3. HORMONES:
i. Human chorionic gonadotropin (hCG) Trophoblastic tumours, non-seminomatous germ cell tumours of testis
ii. Calcitonin Medullary carcinoma thyroid
iii. Catecholamines and vanillylmandelic acid (VMA) Neuroblastoma, pheochromocytoma
iv. Ectopic hormone production Paraneoplastic syndromes
4. CANCER ASSOCIATED PROTEINS:
i. CA-125 Ovary
ii. CA 15-3 Breast
iii. CA 19-9 Colon, pancreas, breast
iv. CD30 Hodgkin’s disease, anaplastic large cell lymphoma (ALCL)
v. CD25 Hairy cell leukaemia (HCL), adult T cell leukaemia lymphoma (ATLL)
vi. Monoclonal immunoglobulins Multiple myeloma, other gammopathies
vii. Prostate specific antigen (PSA) Prostate carcinoma