There are several variations of the mesothelioma cancer known to us. For example, papillary mesothelioma, benign mesothelioma, malignant mesothelioma, etc., without going to deep into the other scientifically relevant forms. Typically, we mostly hear only about the common malignant mesothelioma, which is known for developing very slowly and the onset of symptoms might not occur before twenty or thirty years after a patient has actually started to develop the disease. And we also know that mesothelioma can be effectively treated, however, the general prognosis is still rather poor.

But there is also a variant of mesothelioma diagnosis that is not really heard about, it is called desmoplastic mesothelioma.
Desmoplastic mesothelioma is a very rare form of this kind of cancer. There is barely any literature available, let alone information on the internet. I actually only found one excerpt of a study that was conducted over twenty five years back ago. It was rather small study. Unfortunately, I couldn't find any specific on the study design. As a matter of fact, I wasn't able to find who actually conducted it.

Between 1982 and 1989, two hundred and fifty five patients diagnosed with malignant mesothelioma were observed and examined in order to the desmoplastic version of this disease.
From what I understand, samples of the tumors were taken and further tested in a laboratory. The goal was to identify the counts of asbestos fibre.

Out of the two hundred and fifty five cases, seventeen where concluded as desmoplastic mesothelioma, which equals a percentage of 6.6%. Out of the seventeen cases, six were noted as biphasic cell type and eleven as sarcomatous.
For the sarcomatous variant the mean survival time after the first symptoms manifested and death was 5.8 months and for the biphasic variant it was 6.8 months.
 I wish they would have provided more details on the duration of how long the patients were exposed to asbestos. The only mention I found: twelve out of sixteen were in fact in contact with the material. However, it only says that the actual time of exposure ranged between five months and forty-three years.

Unfortunately I was not able to gather more information about this particular and very rare mesothelioma variant. But as I said before, I only found this one article which had at least a little bit of substance to it.