Context: Serous effusion cytology is an important investigation for diagnosis of neoplastic and non-neoplastic diseases. Malignant cells in serous uid cytology indicates advanced stage. To evaluate the utility of serous ui Aims: d cytology in differential diagnosis of malignant and nonmalignant serous effusions and to emphasize the cytomorphology of rare metastatic malignancies. The importance of cell block with immunocytochemistry for diagnostically challenging cases was also highlighted. T Settings and Design: his was a one year retrospective study in which cases were classied into malignant and non-malignant. Immunohistochemistry was performed on cell blocks of difcult to diagnose cases. Methods and Material: Total 356 serous uids (pleural, peritoneal and pericardial uids) were centrifuged, cytocentrifuged and stained with Papanicolaou and Giemsa. Clinical history, radiological ndings and other relevant parameters were noted. 184 cases were of pleural Results: uid, 168 of peritoneal uid and four were of pericardial uid. Lung malignancies and ovarian malignancies were the most common primary sites in pleural and peritoneal uids respectively. Out of 40 positive for malignancy cases, 22 were rst conrmed on cytology. Clinical diagnosis of Boerhaave's syndrome was conrmed on cytology. Rare presentations of metastasis of squamous cell carcinoma, pleomorphic lobular carcinoma and clear cell type renal cell carcinoma were diagnosed on cytology. Rare m Conclusions: etastatic malignancies to serous cavity pose diagnostic challenges on cytology. Both, cytopathologists and clinicians should be aware of these rare malignancies. A vigilant cytopathologist can identify malignant cells based on cytomorphological features and give accurate diagnosis with the help of ancillary tests and lead clinicians for further work up, evaluation and treatment of the patients

Occurrence of  multiple primary malignant tumors is very uncommon .Co occuring tumors can be synchronous or non synchronous.Tumors presenting within  a period less than or equal to 6 months are called synchronous   and  if they occur after 6 months they are termed as metachronous. Synchronous malignancies are rarer than metachronous.  For  defining  tumors as synchronous  both   the tumors should show criteria of malignancy, possibility of metastasis  must have been ruled out and both the tumors should be pathologically distinct. Breast cancer is the commonest tumor to be associated with other malignancies such as colorectal, endometrial, ovarian carcinoma, yet occurrence of invasive ductal carcinoma with clear cell renal carcinoma is rare. We present a 70 year old female with   synchronous Breast carcinoma and Renal clear cell carcinoma .