To the best of our knowledge, the seven-year latency period between first exposure and complaints, and 8.5 years (14 months lapsed between symptoms and diagnosis) to diagnosis of mesothelioma is the shortest ever reported in an adult. The case for this conclusion rests on both tissular and independent ascertainment of exposure, notably the contemporary report by occupational health authorities specifically referring to asbestos dust exposures at the patient's workplace. The light microscopy technique, with a 60× objective lens is too low a magnification to detect the vast majority of asbestos fibers retained. The moderately elevated concentration above background -in the patient's resected lung is supportive of her past work exposures causing mesothelioma [6–13], given the absence of any other known source. The finding of asbestosis is a strong confirmation that she had substantial asbestos exposure.
We note that the demonstration of several asbestos bodies in a light micrograph of lung tissue when combined with interstitial fibrosis on histology is sufficient also for a diagnosis of asbestosis using standard NIOSH/College of American Pathology criteria . Her unilateral imaging features are not in agreement with pulmonary fibrosis as set by current criteria. However, histologically proved asbestosis has been recognized elsewhere, despite lack of abnormalities on a CT scan . Our case represents indeed a deviant from common acceptance of an incubation of tens of years to diagnosis of this pneumoconiosis [15, 16], with a minimum latency of 10 years . The occupational history and the discovery of asbestos facts in conjunction with the histopathologic detection of interstitial fibrosis make the hypothesis for a "spontaneous case" for mesothelioma most unlikely.
Davis and Rall published a table, which specified that the latent period for cancer in persons with workplace exposures to high volume carcinogens can range from 4 to 40 years . A study from Poland reported 16 cases of pleural mesothelioma found among a cohort exposed from 1987 to 1997. Four of the patients were employed for periods ranging from 3.5 months to five years. Two of the four had latency periods of 11-12 years from onset of occupational exposure. These four patients had occupational and prior residential exposures associated with massive use of commonly available asbestos-cement wastes as road surface material . Our report along with that from Poland calls into question the general consensus that latencies for mesothelioma under 10 years are improbable.
An absence of calcified pleural plaques in our patient may imply shorter latency since exposure [20, 21]. Animal experiments with implantation of asbestos or other fibers in the pleura or peritoneum show that the latent period shortens as fiber dose is increased and lengthens as the dose of fiber is reduced . The present report indicates that high prior exposures, particularly at younger ages, may result in shortened induction periods, in keeping with classic observations on increased dose and shortened latency [22–24].
Individuals with direct exposures associated with the construction trades are apt to be the most heavily exposed . During pregnancy, the physiological augmentation of minute ventilation leads to a greater dust burden into lung parenchyma. As with ionizing radiation, the earlier the age at exposure, the shorter the latency period for asbestos related cancers . Worker cohort studies indicate that earlier age of exposure predicts incremental lifelong adjusted risks for mesothelioma [27, 28] and persons near asbestos work are at risk of "bystander exposure" [29, 30].
In comparison with mixed and sarcomatoid, the epithelial cell type described in our patient, predicts better prognosis [31, 32].