Comparison of computed tomography and histopathological findings among patients with nasopharyngeal tumors at Moi Teaching and Referral Hospital, Kenya.

Abstract

Background: Nasopharyngeal tumors are lesions arising from the tissues of the nasopharynx. They can either be benign or malignant, with the latter being the most common. Clinically, they often present late and they tend to be locally advanced by the time of diagnosis. This causes serious morbidity and mortality to the patients and subsequently a burden to the health care system. Early detection is imperative via Computed tomography (CT) scan which is currently widely available and is essential in assessment of extent of the disease as well as guiding further evaluation including biopsy. Biopsy and histopathology are the gold standard for confirmation of nature of lesion. However, histopathology services are limited to referral hospitals, private laboratories and institutions. This study will increase awareness among radiologists and clinicians on the high index of suspicion for nasopharyngeal malignancies especially where histopathology services are limited. Objective: To describe the accuracy of CT scan in the diagnosis of nasopharyngeal masses using histopathology as the gold standard among patients at Moi Teaching and Referral Hospital (MTRH). Methods: This was a descriptive cross-sectional study carried out from September 2021 to August 2022 at MTRH, Eldoret, Kenya. Census study method was used to enroll a total of 87 consecutive patients. CT scan images were acquired from MTRH CT centres. Histopathology results were obtained from the histopathology laboratory. Data was collected using structured interviewer administered questionnaire with a checklist of demographics, CT neck and histopathological findings. Continuous variables were analyzed using means, standard deviation and categorical variables were summarized in frequency tables, percentages and bar graphs. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were determined using a 2x2 table. An exact McNemar's test and Kappa test were used to determine any statistically significant difference between CT and histopathology. Results: The age of the participants ranged between 6 to 77 years with a mean age of 36 years. Males were more affected at 56.3%. On CT evaluation, 84(96.6%) were suspected malignant lesions while 3(3.4%) were benign. Primary involvement was seen in 65(74.7%) patients while 22(25.3%) were of secondary involvement. Most lesions were of soft tissue density 49(56.3%) and heterogenous enhancement pattern 73(83.9%). Histopathologically, 77(88.5%) of the lesions were malignant while 10 (11.5%) were benign. The sensitivity of CT in the diagnosis of nasopharyngeal tumours was 97.4%, specificity of 10%, positive predictive value of 89.3% and negative predictive value of 33.3%. Conclusion: Malignant tumors were the most common in both radiological and histopathological findings, with nasopharyngeal carcinoma being the most prevalent histological type. Suspicious CT features that correlated with histopathological diagnosis of nasopharyngeal carcinoma were; soft tissue density, heterogenous enhancement, neck spaces and nodal involvement, central skull base, intracranial and vertebral invasion. CT had a high sensitivity but a low specificity in diagnosis of nasopharyngeal lesions. The high sensitivity means that CT can be used for preliminary investigation and screening while a low specificity denotes that it is not a good tool on its own in the diagnosis of nasopharyngeal tumors. Recommendation: Generally, CT scan can be used for accurate diagnosis of nasopharyngeal tumors as it provides high diagnostic yield. To radiologists, subtle features like asymmetric nasopharyngeal mucosal thickening and enhancement on CT imaging should be considered suspicious to enable early detection in combination with histopathology and prompt management. To clinicians, any patient with persistent rhinological & related symptoms should be advised to have neck imaging.