Introduction We evaluated the role of simultaneous use of multiple antibodies in flow cytometry (FCM) to detect metastatic carcinomas in effusion samples. Methods Cytological examination of 75 successive cases of effusion samples was performed. There were 48 peritoneal, 26 pleural and one pericardial fluid. Multi‐coloured FCM examination was undertaken using a cocktail of CD45, CD14 and epithelial cell adhesion molecule (EpCAM), antibodies tagged with different fluorochromes. The percentage of EpCAM positivity was calculated in the CD45 and CD14 dual negative population by selective gating. The EpCAM value was correlated with the cytological findings, follow‐up data and MOC‐31 immunostaining. Results There were 20 benign, 35 malignant and 20 atypical cases diagnosed on cytomorphology. The primary sources of carcinomas were mainly from the ovary, followed by lung, gall bladder, intestine and other areas. Out of 20 cytologically benign cases, there were two malignant cases on the final follow‐up, and EpCAM on FCM picked up all 18 benign cases and one malignant case. Out of 35 cytologically detected malignant cases, EpCAM picked up 32 malignant cases. The EpCAM detected 15/18 malignant and both benign cases out of 20 cytological atypical cases. EpCAM antibody by FCM showed 87% sensitivity, 100% specificity, 100% positive predictive value and 74% negative predictive value. Conclusion This comprehensive study highlights the potential use of multi‐coloured FCM along with cytological examination to diagnose metastatic carcinoma in effusion samples. Multi‐coloured FCM is rapid and quantitative and is helpful in atypical cases.

<b><i>Background:</i></b> The diagnosis of atypical cases in the effusion cytology sample often poses a challenge to the cytologists. <b><i>Aims and Objectives:</i></b> We evaluated the diagnostic role of MOC31 in the metastatic adenocarcinoma in effusion fluid. <b><i>Materials and Methods:</i></b> The cytological examination and MOC31 immunostaining in the cell block sections were carried out in 64 cases of serous effusion. A total of 23 cases showed atypical cytology, out of which suspicious for malignancy (SFM) and atypia of undetermined significance (AUS) were 19 and 4 cases, respectively. In these cases, we also performed calretinin immunostaining. The cytological features, results of MOC31 immunostaining, and follow-up data were correlated to find out the sensitivity and specificity of MOC31 immunostaining in the diagnosis of metastatic adenocarcinoma. <b><i>Result:</i></b> The sensitivity and specificity of MOC31 were 100%. MOC31 detected all the cases of metastatic adenocarcinoma. MOC31 showed strong positivity in 19 cases of SFM. All these cases had a malignant outcome in histopathology or follow-up data. In AUS cases, MOC31 immunostaining was negative with a benign outcome. In all the atypical but malignant cases calretinin stain showed diffuse cytoplasmic and nuclear positivity. In contrast, MOC31 showed strong membranous positivity and occasionally cytoplasmic positivity. <b><i>Conclusion:</i></b> MOC31 is an excellent marker of metastatic adenocarcinoma in the serous effusion. The membranous positivity of MOC31 and negative calretinin immuno­staining are helpful in atypical cytological cases to avoid the diagnostic dilemma. The MOC31 positivity is significantly useful in discrete atypical cells which are more challenging to recognize.

Cytological examination of the effusion fluid provides valuable information regarding the presence of malignancy. At times, it is challenging to diagnose malignant cells in serous effusion. The various ancillary techniques are available to solve the problem including immunocytochemistry, DNA ploidy, and multicolored flow cytometry. At present, the molecular tests on the effusion sample are of growing interest. The effusion sample is rich in cells and cell-free fluid that contains free DNA, cytokines, and extracellular vesicles. Molecular tests in effusion sample not only provide a diagnosis of malignancy but can also give valuable information that may be essential for the individualized therapy, management, and prognostic assessment. In this paper, we reviewed the application of the different molecular tests in the effusion sample.

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Introduction Any type of cutaneous metastasis indicates dismal outcome of the disease. Skin is an unusual location for metastatic deposits from any tumour and has an incidence of about 0.8%‐5%. Fine needle aspiration cytology (FNAC) helps in the rapid diagnosis of metastasis with minimum pain. Aim To study the cytomorphological spectrum of cutaneous metastasis on FNAC. Material and methods A total of 225 patients with diagnosis of cutaneous metastasis on cytology were analysed. May‐Grünwald Giemsa and haematoxylin‐eosin‐stained smears were studied and examined for the cytomorphological spectrum of cutaneous metastasis. Cell block was prepared in a few cases. In a subset of cases, immunohistochemistry was done to pinpoint the primary. Results Amongst the 225 patients studied, the mean age was 53.9 years. There was female preponderance with 125 females and 100 males. The commonest site was abdominal wall (n = 89) followed by chest wall (n = 60). The most common type of metastasising tumour was adenocarcinoma. Conclusion Clinicians and pathologists must be aware of the clinico‐morphological spectrum of cutaneous metastasis for instant diagnosis followed by prompt management.