MM presents infrequently periodical diseases such as
recurrent laryngeal nerve paralysis, recurrent pneumothorax
or recurrent pleurisy as in our patient [
12,
13]. This periodicity
indicates a dynamic competition between host and
tumor for the appearance/disappearance of the disease.
Current concepts of MM biology suggest that the tumor
is, to some extent, immunogenic and in patients with MM,
clinical trials utilising immunomodulatory agents have
shown evidence of response in a proportion of patients
[
14]. The presence of lymphoplasmocytary infiltrates in
tumor stroma suggests that an immunologic mechanism
may be responsible for spontaneous regressions in our
patient. The accumulation of exudative effusions is probably
due to this inflammatory response. When tumor-associated
antigens are eliminated by inflammatory response, the
effusion may regress spontaneously. However, the expression
of a new antigen can cause another exacerbation of
pleurisy. Effusions due to MM tend to disappear in the later
stages but this process is associated with the obliteration of pleural space by tumor tissue [
15]. In our patient, we
did not see any residual lesions in multiple chest CT
investigations.
Dietary or hormonal factors may have a role on the
progression of MM but the patient did not make any changes
in his nutritional habits and we did not observe a specific
finding suggestive for hormonal disturbances [16,17].
The procedure of chemotherapy can alter anti-tumor
immune response but it is important to note that spontaneous
regression of a cancer is rare and transient [18]. On the
other side, miliary dissemination can occur in the absence
of clinically identifiable pleural-based tumor in MM [19].
CONCLUSIONS
Unexplained recurrent pleurisy may be a rare feature
of MM. Despite the aggressiveness of tumor, MM-associated
pleural effusions can spontaneously regress without any
identifiable lesion and the radiological appearance may
change markedly within a short time.
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