We read with interest the scientific letter from Espinosa Muñoz et al., describing the case of a young woman with malignant mesothelioma.1 The main message of the letter was to alert readers to the possibility of mesothelioma developing without known exposure to asbestos. Indeed, in all published series, this exposure cannot be confirmed in around 20% of patients.2 In these cases, exposure to erionite in some areas of Turkey, the effect of the SV-40 virus, or previous radiation have been cited, as mentioned by the authors.

However, the possibility of inadvertent exposure to asbestos must also be taken into consideration. On the basis of this hypothesis, some data that would definitively rule out asbestos exposure in the case under discussion are missing. In the first place, the absence of environmental or domestic exposure should be confirmed, since mesotheliomas have been reported in association with proximity to several industries, such as fiber cement factories,3 or in association with certain domestic appliances or installations. As there is no safe threshold for asbestos exposure in the development of mesothelioma, environmental or domestic exposure in the patient's early years of life could have caused the tumor 20 years later. We would also like to point out that, in an exceptional case such as this, an analysis of the asbestos content in the surgical resection piece would have been very illustrative. Our group is very familiar with this technique, which is used to determine the presence of asbestos bodies in the lung, expressed as number of bodies per gram of dry lung tissue. The number of asbestos bodies correlates well with the number of fibers and is an indication of the asbestos retained in the lung after inhalation, particularly in the case of the amphybole variety. Since this test is performed on lung tissue left over after the histological study, it is of great interest in cases such as the one discussed here, if sufficient sample material is available.

Indeed, study of the lung quite often provides evidence of exposure to asbestos that has gone unnoticed by patients themselves.4 In asbestos-related diseases, diagnosis is based mainly on a history of patient-reported exposure, along with a suggestive clinical and radiological picture. However, in doubtful cases, like this one, in which radiological or histological findings conflict with the data obtained from the case history, it is interesting to obtain objective evidence of such exposure, which can have clear diagnostic and medicolegal repercussions.5