Correlation f Clinical Diagnosis of Squamous Cell Carcinoma or Lymphoma and Confirmatory Immunohistochemistry Results of Cytokeratin (CK) or Leukocyte Common Antigen (LCA) Among Patients with Undifferentiated Carcinoma of the Nasopharynx

Objective: To determine the correlation between clinical diagnosis (Squamous cell carcinoma or Lymphoma) and immunohistochemical results (Cytokeratin or Leukocyte Common Antigen) among patients with undifferentiated nasopharyngeal malignancy. Study Design: Analytical, cohort study Setting: Tertiary private hospital in Metro Manila Sample population and Methodology: Patients diagnosed of undifferentiated nasopharyngeal malignancy for the recent five (5) years were included in the study. Clinical diagnosis of nasopharyngeal squamous cell carcinoma or lymphoma was correlated with positive immunohistochemistry of cytokeratin (CK) and Leukocyte Common Antigen (LCA) respectively. Results and Conclusion: The results showed that there was a significant association between the clinical diagnosis and immunochemistry results (p value 0.05). Among the 23 patients with clinical diagnosis of squamous cell carcinoma, only 19 patients (82.6%) were confirmed with CK reactivity while 4 cases were reactive with LCA. Among the 7 patients with clinical diagnosis of Lymphoma, only 4 patients (57.1%) were confirmed with LCA reactivity while 3 were positive for cytokeratin. A total of 22 patients were interpreted as cytokeratin positive (73.7%) and 8 patients were LCA positive (26.3%). Hence, there was a relatively fair association between clinical diagnosis of lymphoma and confirmatory LCA immunostain.


Introduction
Diagnosis of nasopharyngeal cancer depends upon a good history, physical examination findings and ancillary procedures.
Nasopharyngeal lesions whether squamous cell carcinoma or lymphoma may manifest with epistaxis, middle ear effusion and neck nodes early in the disease process while cranial nerve deficits such as abducens nerve palsy or diplopia are late manifestations [1]. It has to be emphasized that in order to arrive to an accurate diagnosis, a good history taking is indispensable as well as a discerning clinical eye. This is essential because a correct diagnosis will determine the 480 appropriate course of treatment regimen of a particular case. Nasal endoscopy is usually done to assess and ascertain any abnormalities in the nasal cavity and nasopharyngeal vault. Tissue obtained from nasopharyngeal punch biopsy is done to confirm the diagnosis.
When histopathologic result would reveal undifferentiated carcinoma, this would require immunohistochemical analysis to determine whether it is squamous cell carcinoma or lymphoma.
A local study by Cachuela

Review of Related Literature
Immunohistochemistry (IHC) is the process whereby antibodies are used to detect antigens. Major components in a complete immunohistochemistry are: a) Primary antibody binds to specific antigen. b) Antibody-antigen complex is formed by incubation with a secondary, enzyme-conjugated, antibody.

c)
With presence of substrate and chromogen, the enzyme catalyzes to generate colored deposits at the sites of antibodyantigen binding.
This can be done with simple staining, immunofluorescence, immunoenzymological staining or immunocolloidal gold technique [3]. Immunological methods can now resolve the majority of difficulties arising over the histological diagnosis of "unclassifiable" tumors. In immunohistochemistry, the features evaluated are location of immunoreactivity, identification of immunoreactive cells, and intensity of immunoreactivity [2]. The LCA has membranous tumor immunoreactivity while CK has cytoplasmic tumor immunoreactivity. Immunostaining using LCA and CK to confirm undifferentiated tumors in the head and neck allows definitive diagnosis of either carcinoma or lymphoma by 100% [2]. Validation of immunohistochemical stains for their specificity and sensitivity studied by Kutin [4], Michels [5] and Wick [6] showed that LCA is an excellent cell marker to distinguish hematopoietic neoplasms, particularly of the lymphoid type, from poorly differentiated tumors of epithelial, mesenchymal and neural derivation. The specificity of the LCA immunostaining technique was 100% and its sensitivity was 96%. In a study by Michie [7] to distinguish undifferentiated tumors with a histologic differential diagnosis of carcinoma versus lymphoma using immunostain anti-CK and anti-LCA, the results indicate specificity of 100% and sensitivity of 86%.
Hence, correlating clinical diagnosis of squamous cell carcinoma and lymphoma with CK and LCA respectively would be necessary to determine the accuracy of clinical impression.

General objective
To determine the correlation between clinical diagnosis

Research Design
This is an misperceive, cohort study with prospective and retrospective enrolment. The sample population included review of old and new cases of patients with undifferentiated carcinoma of the nasopharynx.

Sample Population
Patients who consulted or were admitted at the MCU- for those patients seen / admitted in the past.

481
The patients' clinical history with emphasis on ENT complaints such as nasal obstruction and / or epistaxis, aural fullness and effusion, smoking history were recorded. If nasopharyngeal mass was seen on endoscopy, punch biopsy was done, and the specimen was sent for histopathology. If the result was undifferentiated carcinoma, the patient would be included in the study and the specimen was sent for immunohistochemistry (CK and LCA) for confirmation of the diagnosis. The patient was informed about the study and informed consent was secured.

Sample Size
Using the 95% confidence level, the ideal sample size was computed to be n=73. However, due to the limited number of cases, the sample size is smaller and would only be limited to the number of cases seen during the period covered. It has to be stated that this is a limitation of this study. (Zα)2pq where Zα =1.96 at 95% confidence interval 95% = 0.95

Results
Out of 84 patients with endoscopic findings of nasopharyngeal     Table 4 shows the association of clinical signs/ symptoms with immunohistochemical results. The results showed that there was no significant association (p values >0.05) except for cervical mass (p=0.03) which was present among patients who were LCA positive than those with Cytokeratin (Table 5).    There are different types of malignancy which may develop in the nasopharynx which include squamous cell carcinoma, lymphoma, salivary gland malignancy, and sarcomas [8]. The most common are squamous cell carcinomas, which can be divided into 3 types of cell differentiation (well, moderately or poorly differentiated), and are collectively called nasopharyngeal carcinoma. The nasopharynx is lined by either stratified squamous epithelium or pseudostratified columnar epithelium where squamous cell carcinoma commonly originates. The nasopharyngeal mucosa also contains salivary and lymphoid tissues, so that salivary tumor and lymphoma may develop although less frequently [9]. The gross appearance of the mass is usually descriptive of the type of malignancy that is involved; a smooth bulging nasopharyngeal mass is noted in lymphoma while a friable corrugated appearance of the mass, infiltrative or exophytic, is commonly seen in squamous cell carcinoma [1,9]. Undifferentiated carcinoma (previously WHO III) is composed of cells with indistinct margins and round to oval nuclei with prominent, round nucleoli. The cells tend to grow in a syncytium rather than having a stratified or pavemented appearance. The tumor can grow in well-defined epithelial aggregates (Regaud pattern) descriptive of a carcinoma. It grows as ill-defined sheets, small clusters, or individual cells admixed with lymphocytes (Schmincke pattern). It is most often found in children, has a strong correlation with EBV, tends to disseminate, and has a good response to irradiation [12]. In this study, out of the 30 patients diagnosed  cytokeratin who presented with multiple neck nodes with smooth lobulated or only slightly elevated nasopharyngeal mass, hence, the initial impression was lymphoma. Patients with clinical impression of squamous cell carcinoma, on the other hand, who were reactive to LCA, had history of chronic nasal obstruction or decreased hearing / aural fullness, which are frequently seen in patients with squamous cell carcinoma. Both LCA and CK immunostain are specific (100%) and sensitive (86-95%) to lymphoid and epithelialderived tissues respectively [2]. Squamous cell carcinoma in general is responsive to radiation therapy in contrast to lymphoma which is treated with chemotherapy.8 Arriving at the appropriate histologic diagnosis is important to guide medical practitioners in choosing the appropriate treatment.

Conclusion
The results showed that there was a significant association between the clinical diagnosis and immunochemistry results Immunostaining is necessary to confirm the diagnosis.