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IMMUNOHISTOCHEMISTRY (IHC) AS A MAIN TOOL IN TUMOR DIFFERENTIAL DIAGNOSIS
Donscaia A., Chemencedji I., Antoci L., Cernat M., Mednicov L., Gherasim M.,
Institute of Oncology, Republic of Moldova E-mail: donscaia53@mail.ru
IMMUNOHISTOCHEMISTRY (IHC) AS A MAIN TOOL IN TUMOR DIFFERENTIAL DIAGNOSIS
Abstract: The value of the immunohistochemistry (IHC) method used in the differential diagnosis of primary tumors and metastatic tumors with unknown primary was estimated. From 323 cases where IHC was performed, in 254 cases it was used for target therapy selection in breast cancer patients. GIST was confirmed in 73 cases. From 96 cases of various biopsy and surgical excision samples, 23 cases of retroperitoneal tumor masses were studied detail. In 12 cases, tumors were primary and in 11 cases, there were retroperitoneal lymphadenopathies with unknown primary. The value of certain monoclonal antibodies positivity for exact diagnosis was estimated. In conclusion, we consider that IHC is an important investigation method for the differential diagnosis of tumors with unknown origin.
Keywords: IHC, primary tumor, metastatic tumor, differential diagnosis.
Introduction gin in metastatic cancer with unknown primary in about 90%
IHC technique is used in the search of cell or tissue anti- cases [5]. gens that range from amino acids and proteins to infectious Materials and methods
agents and specific cellular populations [1].
IHC method has brought about a revolution in the identification of tumor tissue origin and remains a vital component of laboratory testing today. In the emerging era of personalized medicine, IHC continues to serve as a valuable tool, complementing and enhancing other molecular techniques. This method is a surrogate for traditional cytogenetic and in "situ" hybridization-based identification of chromosomal abnormalities, if not a viable molecular technique in its own right. In oncology, the method is used for diagnosis, as well as for prediction of therapeutic outcomes [2].
IHC is an important tool for scientific research - as a complementary technique for the diagnoses that are not determinable by traditional analyses (with hematoxylin and eosin) and for the optimization of treatment regimens through patient stratification based on prognostic factors [3].
Specific examples for IHC method use are cases with metastatic tumor samples of unknown primary. Using a panel of different antibodies that target tissue-specific proteins, one could find the primary site of the tumor, reason of great importance for treatment planning. Metastatic cancer with unknown primary is registered in 2-9% of primary detected tumors worldwide [4].
Greco F.A (2013) considered that using IHC method and gene-expression profiling would allow to determine tissue ori-
IHC is a powerful microscopy-based technique used for the visualization of cellular components, for instance proteins or other macromolecules in tissue samples. The tests are performed on formalin-fixed paraffin-embedded tissue blocks. Labeled polyclonal or monoclonal antibodies added to examined tissue react with tissue-specific antigens. The results of these reactions are determined by immunofluorescent, enzymatic or indirect methods (an unlabeled primary antibody reacts with the tissue antigen and a secondary labeled antibody is added to this complex).
In our study, IHC was performed in 423 cases, during last two years. The IHC method was used for determining tumor receptor status in patients with breast cancer and for the differential diagnosis in cases when traditional histopathology methods could not determine tumor origin of metastasis sample with unknown primary. The study is based on indirect method using monoclonal antibodies.
The following monoclonal antibodies were used: CD20, CD45, CD34, CD117, chromogranin A (ChgA), S-100, cy-tokeratin 20 (CK20), neuronal nonspecific enolase (NNE), melan-A, podoplanin (PDPN), desmin, vimentin. Proliferation state was determined by Ki-67 level, in GIST and breast cancer specimens.
Estrogen and progesterone receptors and HER-2 receptors were determined in patients with breast cancer (254
Medical science
cases) in order to estimate disease prognosis and to decide target treatment. ICH is of great importance for such procedures.
In 73 cases suspect for GIST, positive reaction for CD34, CD117, S-100 and vimentin allowed to confirm the diagnosis.
In 96 cases, where classic histology methods could not determine the tumor origin, IHC led to definitive tumor diagnosis. These cases included biopsy and operative samples from tumors with many localizations: peripheral and retro-
Table
peritoneal lymph nodes, retroperitoneal tumors, bone, lung and stomach biopsy samples. We studied in detail the results of IHC used in 23 cases of retroperitoneal lymphadenopathies and retroperitoneal tumors.
Results and discussion
The studied cases presented 11 retroperitoneal lymphadenopathies with unknown primary and 12 cases of retroperitoneal tumors of uncertain origin. The results of monoclonal antibodies tests that were used are presented in (table 1).
NHL Seminoma Melanoma Myosarcoma NET GIST
CD20 + — n/a n/a n/a n/a
CD45 + — n/a n/a n/a n/a
CD34 n/a n/a n/a n/a n/a +
CD117 n/a + n/a n/a n/a +
ChgA n/a n/a n/a n/a + n/a
S-100 n/a n/a n/a n/a n/a +
CK20 n/a n/a n/a n/a n/a n/a
NNE n/a + n/a n/a n/a n/a
Melan-A n/a n/a + n/a n/a n/a
PDPN n/a + n/a n/a n/a n/a
Desmin n/a n/a n/a + n/a n/a
Vimentin n/a n/a n/a + n/a +
In all 11 cases of retroperitoneal lymphadenopathies, IHC allowed to determine the origin of the primary tumor. In six cases, NHLB-lymphoma was confirmed by positive CD20 and CD45 and negative cytokeratin-20. In three cases, positive Melan A and negative cytokeratin-20 and CD45 allowed to establish the diagnosis of metastatic melanoma. In two cases podoplanin and CD117 antibodies positivity and CD45, CD20, desmin and NNE negativity were of great importance for determining metastatic seminoma.
From 12 cases of primary retroperitoneal tumors that were analyzed by IHC, five cases were sarcomas (negative to CD117, CD34 and positive to desmin and cytokeratin). Four cases of biopsy samples from massive tumors were positive to CD34, CD117 and S-100 so the diagnosis of GIST with retroperitoneal involvement was established.
In three cases only a test for chromogranin-A managed to confirm the neuroendocrine origin of the tumor, one of these
cases being determined retrospectively, in a sample from a tumor excised in another hospital a year earlier.
The results obtained by IHC in tumor samples of uncertain origin gave us the possibility to establish an exact diagnosis in primary, as well as in metastatic retroperitoneal tumors with unknown primary.
Our data led us to the following conclusions:
1. IHC is a modern diagnostic method for identifying the tissue origin in primary tumors and metastatic tumors with unknown primary.
2. Hematological malignancies like B-cell NHL demonstrated positive results only for CD20 and CD45 antibodies.
3. Positive results for CD34, CD117, vimentin and S-100 antibodies are characteristic for GIST.
4. Chromogranin A test is of great importance in neuroendocrine tumor diagnosis.
References:
1. Matos L., Trufelli D. C., de Matos D. G., da Silva Pinhal M. A. IHC as an Important Tool in Biomarkers Detection and Clinical Practice. Biomark Insights. 2010; 5: 9-20.
2. Swanson P. E. Immunohistochemistry as a surrogate for molecular testing: a review. Appl Immunohistochem Mol Morphol. 2015; 23(2):81-96.
3. Diagnosis and Management of Metastatic Malignant Disease of Unknown Primary Origin. NICE Clinical Guidelines, -No. 104. 2010.
4. Winson W. Tan et al. Metastatic Cancer with Unknown Primary Site. Medscape. 2016.
5. Greco F. A. Molecular diagnosis of the tissue of origin in cancer of unknown primary site: useful in patient management. Curr Treat Options Oncol. 2013; 14 (4): 634-42.
