Depending on the type of mesothelioma and clinical presentation, there are several samples that may independantly and collectively be examined to diagnose mesothelioma. Optimisation of sampling is crucial as it can greatly affect and inhance the pathpologist’s ability to offer a correct diagnosis.
Although wedge biopsies – and even open biopsy via thoractomy – are sometimes required to establish a diagnosis for mesothelioma, there are several less invasive forms of sampling which may be diagnostic in some settings.
These latter samples are discussed as below:
When a serous effusion is present an adequate sample (preferably over 50ml of fluid) should be collected and sent to the cytology laboratory; this will enable smears and a cell block to be prepared. In addition, som of the cell deposit can be set aside for ultrastructural examination. A definate diagnosis of malignant mesothelioma can be made on cytology of effusions in the majority of cases.
Closed Needle Biopsy
Although taking a close needle biopsy (of the Abrahams’ type) at the time of tapping the effusion was the standard practice in the past, there has been a reduction in this form of sampling related to a significant proportion of inadequate or inconclusive biopsies. The high diagnostic yield from effusion cytology has probably also influenced this decline.
Fine Needle Aspiration (FNA)
Over the past years – there has been an increase in thin core sampling for plueral-based lesions, especially where there is no accompanying serous effusion. This procedure is well tolerated by patients who require only a simple local anaesthetic.