Body fluid cytology is a globally used diagnostic method with origins dating back to the 19th century. Lucke and Klebs were credited as the initial researchers to identify cancerous cells in ascitic fluid in 1867 [3]. Cytology is the examination of either exfoliated cells or cells obtained by aspiration using a needle. The often analysed specimens consist of pleural fluid, ascitic fluid, pericardial fluid, synovial fluid, and cerebrospinal fluid (CSF) [4]. Cytological examination of these fluids helps in diagnosing both non neoplastic and neoplastic conditions. Most important is the recognition of a malignant pathology. But many other conditions such as inflammatory diseases, parasitic infestations, bacteria, fungi and viruses can also be identified. [5] Cytological study of body fluid is a complete diagnostic modality. Firstly, it assists the clinician in formulating and pointing out the aetiology of effusion and list of differential diagnoses. Secondly it allows one to follow the results of therapy and prognosis. [6]

The present study was conducted on body fluids received in the Cytopathology section of Department of Pathology, PDU Medical College and Hospital; Rajkot, Gujarat, India  for duration of 18 months from September 2022 to February 2024. A total of 783 cases were studied. Data was collected using pre-structured proforma. Clinical details such as age, sex, history, sociodemographic details and accompanying clinical presentation/ diagnosis were documented from the requisition. Volume, colour and clarity of the received fluid were documented. Direct smears and cytospin smears were prepared. Cerebrospinal fluid and urine samples were processed by cytospin method (at 2500 rpm for 5 minutes) and all other body fluids were centrifuged (2000 rpm for 10 minutes). The smears were stained with May Grunwald Giemsa stain and Haematoxylin & Eosin Stain. Papanicolaou’s stain was used in case of presence of atypical cells. Cytomorphology of the cells was studied by microscopy and documented paying attention to cellular arrangement, cytoplasmic features and nuclear characteristics.

In our study, a total of 783 cases were studied out of which 67.9% of patients were males while 32.1% of patients were females. (CHART 1)

                  Table 1: Distribution of patients according to Residence

                 Table 1 shows the distribution of patients according to residence in the present study.

Chart 2 shows age wise distribution of patients and Chart 3 shows the distribution of patients according to socioeconomic status. 72.7% of patients belonged to lower socioeconomic status followed by 17.9% of patients from middle socioeconomic status. Only 9.4% of patients were in the high socioeconomic status.

Chart 4 shows the distribution of patients according to type of specimen. Pleural fluid specimen was the most common specimen and was obtained in 493 patients followed by 135 patients whose peritoneal fluid was obtained.

Chart 5 shows the distribution of patients according to diagnosis based on fluids cytology. 63% of patients were diagnosed with infective/inflammatory etiology while 32.3% of patients were diagnosed with other conditions (like dispersed atypical cells, degenerated cells, reactive mesothelial cells, etc.), 3.4% of patients were diagnosed with neoplastic condition (including highly suspicious and malignant aspirates) while 1.3% of patients had unsatisfactory sample.

Table 2: Distribution of fluids in neoplastic category

Table 2 shows distribution of fluids according to microscopic findings. Malignancy type which was most commonly identified was Adenocarcinoma found in 5 patients from whom 3 samples were from pleural cavity, 1 from ovarian cyst and 1 from peritoneal cavity.

Table 3: Distribution of type of diagnosis according to gender

Table 3 shows the gender wise distribution based on diagnosis

Cytological examination of body fluids remains a cornerstone of diagnostic pathology in clinical practice. However, the diagnostic accuracy of cytology is limited by several factors, including sample quality, cellularity, and interobserver variability. False negatives can occur due to inadequate sampling, poor preservation, or prior treatment. The integration of advanced techniques, such as immunocytochemistry, molecular diagnostics, and digital cytology, can help overcome these limitations by improving sensitivity and specificity. The following is a comparison of our present study findings with those in existing literature to see for generalizability of results- In present study it is observed that the incidence of effusions is higher in males (532 cases or 67.9%) compared to females (251 cases or 32.1%) with male: female ratio as 2.12:1 which are consistent with other studies.

Table 4: Distribution of patients according to gender in various studies

219 patients were aged 60 years and above followed by 138 patients in the age group of 50 to 59 years. These results are in concordance with what is reported by Patel M et al. [7], Samar A.EL Sheikh [13] and Dagli A.F et al. [14]. The highest cases of neoplastic etiology lie under age group of 60 and above as the chance of malignancy increases with increasing age due to accumulation of mutations or decline of immunity. 85.2% of patients were from rural background as compared to only 14.8% of patients from urban areas. Patients were categorized according to their employment into various socioeconomic classes. 72.7% of patients belonged to lower socioeconomic status. More number of cases came from rural background and lower socio economic status as chances of infection are more in them due to less hygienic conditions, overcrowding, etc. In all age groups, the majority of fluid specimens were obtained from specimens of pleural fluid followed by specimens of peritoneal fluid. These results are similar to Saxena P et al [16], Saba H. [15] and Lekha NB et al [11].

3.4% of patients (27 cases) were diagnosed with neoplastic condition out of total 783 cases whereas other 96.55% of patients (756 cases) were reported non-malignant.

Table 5: Distribution of patients according to diagnosis of malignant versus non-malignant in various studies

Non-malignant cases include infective/ inflammatory cases like Koch’s effusion, empyema, neutrophilic effusion, etc and other cases like degenerated cells, dispersed cyst macrophages. Also unsatisfactory smears like smears with low cellularity are counted in it. In present study out of 783 cases, 4 are suspicious of malignancy, 5 cases are highly suspicious of malignancy and malignant cells are seen in 18 cases. Total malignant cases totals up to 27, in which malignant cells are seen. Malignancies like Non-small cell carcinoma, High grade carcinoma, Papillary adenocarcinoma are reported. Malignancy type which was most commonly identified was Adenocarcinoma found in 5 patients. Similar findings are seen by other studies.

Table 6: Various studies showing predominance of adenocarcinoma among malignant cases

According to Wong JW et al., pleural fluid showed the highest rate of positivity for malignant cells among all body fluids examined [25]; while no malignant lesions were diagnosed in CSF and synovial fluid samples. These findings are in agreement with the study of Saba H. [15], Sharma M. et al [26] and Kol PC et al [26]. Inflammatory lesions are seen in 25% of CSF and 80% of synovial fluids. 13.53% of samples are purulent/ turbid. Majority of the fluids (47.25%) have neutrophils as a predominant cell type followed by lymphocytes (32.56%). These turbid samples suggest infective/ inflammatory etiology. It is important to note that haemorrhagic fluid often raises suspicion of malignancy. Majority of malignant cases presented as haemorrhagic fluids (17 out of 27 malignant fluids in our study), which is significant because the detection of malignant cells in any effusion generally indicates a poor prognosis.

The cytological study of body fluids is an essential diagnostic tool in the clinical evaluation of various diseases, particularly in a tertiary care setting. Our study also emphasized the role of cytology in the early detection of metastatic disease, which is crucial for timely intervention and improved patient outcomes. In conclusion, the cytological examination of body fluids remains a cost-effective, minimally invasive, and highly informative diagnostic procedure in a tertiary care setting. It continues to be invaluable in the rapid assessment and management of patients, guiding clinical decision-making, and contributing to better health outcomes. Future advancements in cytological techniques and integration with molecular diagnostics may further enhance its diagnostic accuracy and clinical utility.

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