filaria , a vector - borne disease , is common in tropical countries like india . it is a major health problem in endemic areas , especially along sea coasts where lung manifestations due to filariasis are common . filarial parasites have been isolated from many uncommon sites.[13 ] in our case , it was isolated from pleural fluid . hence , it has been reported for its rarity and need for its suspicion in idiopathic pleural effusions . the rarity of this case is all the more unique due to the association of concomitant lung malignancy . a 70-year - old man presented with cough with expectoration and shortness of breath since 6 months . on further enquiry , he had repeated hospital admissions for cough with expectoration since the past 6 months . he had undergone coronary artery bypass graft ( cabg ) surgery 5 years back . on examination ( o / e ) the patient was moderately built and nourished . erythrocyte sedimentation rate was elevated at 60 mm at the end of the 1 h. his blood chemistry was within normal limits . chest x - ray showed a right - sided pleural effusion [ figure 1 ] . sputum for acid fast bacilli ( afb ) and pyogenic organism culture / sensitivity was negative . biochemically , it was an exudative effusion with lymphocyte pre - dominance ( 75% ) . pleural fluids adenosine deaminase ( ada ) and carcino embryonic antigen ( cea ) levels were within normal limits . pleural fluid gram staining showed only few polymorphs but no organisms were isolated in culture . pleural fluid cytology showed only rbcs admixed with few inflammatory cells and mesothelial cells but no definite malignant cells . right - sided pleural effusion on chest radiograph pleural fluid cytology showing microfilariae multidetector computed tomography ( ct ) of the chest revealed right upper lobe cavitatory mass with thick irregular walls with heterogeneous enhancement and posterior pleural thickening . small sub - pleural cystic foci were seen in the rest of the lung fields . echocardiography showed mild mitral regurgitation ( mr ) with mild left venticular ( lv ) systolic dysfunction , consistent with old myocardial infarction . bronchoscopy was done that revealed purulent secretions in the basal segment of the right lower lobe . lavage fluid analysis revealed polymorphonuclear leucocytes ( pmns ) , but was negative for any growth or malignant cells . a ct - guided fine needle aspiration cytology ( fnac ) done from the wall of the cavitatory mass revealed adenocarcinoma of lung . he was put on diethyl carbamazine for 3 weeks and he promptly responded for the same . filaria is still a major health problem in many endemic areas of india , especially along the sea coasts and along the banks of major rivers . filarial effusions tend to be chylous in nature due to leakage of chyle from the occluded thoracic duct . exudative effusion may be due to lymphangitis resulting from incomplete obstruction of lymphatics . in our case tropical pulmonary eosinophilia ( tpe ) is a form of occult filariasis characterized by pulmonary infiltrates on chest radiograph and peripheral eosinophilia . they present with paroxysmal dry cough , wheezing , dyspnea , anorexia , malaise and weight loss . tpe results from a hypersensitivity response to the microfilariae of the lymphatic - dwelling parasites , usually related to w. bancrofti or b. malayi infection . in our case there have been few case reports where filarial microfilariae have been detected in association with malignancy.[811 ] most of the authors have explained that as microfilaria circulate in the vasculature and lymphatic system , and whenever the neoplastic lesion causes vasculature or lymphatic obstruction , they appear in the tissue fluid or shed off into the surface material . in malignancy , increased blood vasculature also causes the increase in deposition of microfilaria to these sites . gupta , et al . reported six cases where microfilaria were found in body fluids cytology and fnac smears in association with tubercular pleural effusion / lymphadenitis , pregnancy , non - hodgkins lymphoma , malnutrition and young age . although the finding of microfilaria in cytological smears was considered incidental , the association of microfilaria with debilitating condition suggests that it is an opportunistic infection . in the literature hence , a meticulous search for any malignant foci is warranted in all cases of filarial pleural effusions . but , many cases of idiopathic pleural effusions have also been known . in cases where tuberculosis or malignancy is a remote possibility , filarial etiology can be considered , more so in the endemic areas or with recurrent pleural effusions . filariasis is endemic in india and therefore , the co - existence of pleural effusion and filariasis may be coincidental rather than causally related . however , the presence of microfilariae in the pleural fluid and the successful response to treatment with diethylcarbamazine , as in our case , is strong evidence of the filarial etiology of the pleural effusion . it is therefore stressed that in tropical countries , careful search for microfilaria in centrifuged pleural fluid may be rewarding .
filaria has a wide spectrum of presentation . 
 we hereby present a case of filarial pleural effusion that is a rarity in itself . 
 filarial lung involvement is usually in the form of tropical pulmonary eosinophilia with pulmonary infiltrates and peripheral eosinophilia , unlike our case where isolated pleural effusion of filarial etiology was detected . 
 microfilaria has been isolated from pleural fluid in very few cases , and ours was one such . 
 of late , there have been many incidental detections of filarial parasites from varied anatomical sites in association with malignancy . even in our case 
 , we had one such unusual association .