Diagnostic significance of immunohistochemistry in cases of undifferentiated nasopharyngeal carcinoma

Background: Undifferentiated nasopharyngeal tumors represent a great diagnostic difficulty in pathology laboratories specially in small crushed pathology specimens. Many of such tumors are anaplastic and difficult to distinguish from other neoplasms such as malignant lymphoma or soft tissue sarcoma. Antibodies to cytokeratin (CK) have been shown to be of diagnostic value in assessment of epithelial nature in both primary and metastatic poorly differentiated neoplasms. also common leukocytic antigen (CLA) and desmin help in exclusion of non-hodgkin's lymphoma and soft tissue sarcoma. Material and Methods: Twenty eight nasopharyngeal tumors were collected from surgical specimens received at Pathology Department - Zagazig University, Egypt, during the period from may 2005 to december 2008. All biopsy specimens were subjected to routine histopathological diagnosis and immunohistochemical staining by broad spectum cytokeratin (CK), (CLA), and desmin. Results: All cases of undifferentiated nasopharyngeal carcinoma revealed variable degree of positive immunoreactivity for cytokeratin, regardless of their degree of differentiation with negative staining reaction for desmin and CLA. The three cases of non-hodgkin's lymphoma were positive for CLA and negative for desmin and cytokeratin which stained only dendritic cells. The case of rhabdomyosarcoma revealed strong positive staining for desmin with negative reaction for cytokeratin and CLA. Conclusion: Immunostaining for broad-spectrum cytokeratin, CLA and desmin monoclonal antibodies have a great diagnostic aid in diagnosis of undifferentiated nasopharyngeal tumors with consequent effect on treatment and prognosis. Also the regular positive cytokeratin immunoreactivity in undifferentiated nasopharyngeal carcinomas supports the view that these tumors are homogenous group exhibiting variable degrees of squamous differentiation.