Diagnostic Utility of AgNORs Staining of Serous Effusion among Sudanese Patients

Serous effusion is a condition of excess accumulation of fluids in serous cavities i.e. (Pleural, Peritoneum, Pericardium) due to different underlying pathological conditions, which vary from inflammatory conditions to primary or secondary malignancies. Some reports suggest that as many as 50% of the patients with lung cancers or breast cancers will develop pleural effusion [1]. The commonest primary malignant tumors causing metastases to the serous cavities are adenocarcinoma of the breast, lung, ovary, stomach, large intestine, pancreas, thyroid, kidney, sarcoma and malignant thymomas [2]. In Sudan the most common aetiology of accumulation of benign serous effusions are inflammatory conditions while metastatic malignancies are the major cause of malignant effusions, while primary malignant mesothelioma is very rare condition, few cases are reported in areas with endemic exposure to asbestos. After aspiration of effusion a set of laboratory investigations should be conducted to identify the nature of the effusion constituents, and it is chemical composition. Effusion sample must be submitted to cytopathology lab to identify its cellular component, which contributes to the identification of malignant cells involving the serous cavities, and is usually made by conventional Papnicolaou (Pap) staining technique. Ancillary techniques such as image analysis and flow cytometry have proved useful in the distribution of benign and malignant fluids but, they are not readily available in most laboratories in the Sudan. Immunocytochemistry (ICC) is probably the most frequently used ancillary technique applied to effusion diagnosis; it can provide reliable insights into various diagnostic dilemmas in effusion cytology. So far many antibodies have been used in serous effusions to enhance the diagnosis with varying degree of efficacy [3]. The serous effusions represent a common and challenging diagnostic problem with diverse and non-similar aetiology. Current methods which applied in this task are either insufficient or invasive. Immunocytochemistry plays an important role in diagnosis and patients management through its ability in determining the nature of the cells that encountered in the effusions and the discrimination between reactive and neoplastic cells that underlying the disease. In certain conditions benign serous effusions, produce reactive mesothelial cells, mimicking the morphology of the neoplastic cells, which increase the difficulties of diagnosing of metastatic carcinomas which is often associated with the reactive mesothelial hyperplasia, and the morphological variations of the mesothelial cells offer great potential for negative diagnosis, and false positive diagnosis which can have a real disastrous consequences for patients [4]. A comparatively simpler technique used for this purpose is the silver staining of nucleolar organizer regions (NORs). Which attempts to add useful diagnostic criteria especially in the differentiation between benign and malignant effusions [5]. A comparatively simpler technique Interphase AgNORs are the structural and functional units of the nucleolus which contain all the essential components for the synthesis of ribosomal RNA. In the human karyotype, NORs are located in each of the short arms of the acrocentric chromosomes 13, 14, 15, 21 and 22. [6] The two argyrophilic proteins which are associated with rRNA transcription and processing are nucleolin and nucleophosmin. [7] These proteins are argyrophilic and are easily stained by silver stains. After silver -staining, the NORs can be identified as black dots present throughout the nucleolar area. The number and size of NORs reflect cell activity, proli feration and transformation and help to distinguish benign from malignant cells. [8] Evaluation of the quantitative distribution of AgNORs has been applied in tumour pathology both for diagnostic and prognostic purposes. A number of studies carried out in different tumour types demonstrated that malignant cells frequently present a greater AgNOR count than corresponding non-malignant cells. [9,10] In the present study, this technique has been applied to differentiate malignant cells from reactive mesothelial cells in pleural and peritoneal effusions.