Pneumonia due to Mycoplasma pneumoniae in granulocytopenic children with cancer

To the Editor: Mycoplasma pneumoniae causes communityacquired pneumonias in children and adults [1]. Diagnosis is based on clinical symptoms, radiological signs, and detection of IgM and IgG by enzyme-linked immunosorbent assay, but polymerase chain reaction (PCR) on a throat swab specimen represents a specific and rapid diagnostic method [1]. Oddly, M. pneumoniae is not included among the possible causes of pneumonia in immunocompromised hosts [2] and a comprehensive MEDLINE search yielded only a total of 11 cases [3–5]. After the observation of a severe pneumonia with diffuse bilateral lung infiltrates and hemolytic anemia due to M. pneumoniae in a splenectomized patient previously treated for Hodgkin disease, we checked for M. pneumoniae infection in pneumonias observed in children with cancer or receiving hemopoietic stem cell transplant (HSCT) at G.Gaslini Children Hospital, Genoa, Italy. From 2006 to 2008, 463 children were treated for a malignancy or received a HSCT for a non-neoplastic disease. The Table reports on the 30 cases of pneumonia observed. In the 3 (10%) cases due to M. pneumoniae, two in patients with non-Hodgkin lymphoma and one with acute myelogenous leukemia, the pathogen was detected by PCR on throat swabs. In all cases the onset of the disease was represented by febrile granulocytopenia with symptoms of pneumonia (14% of pneumonias in granulocytopenic patients), with lung infiltrates (Fig. 1), in two cases bilateral (Fig. 1, panels B,C) at CT scan. All patients were receiving co-trimoxazole for P. jiroveci prophylaxis. Empirical antibacterial (piperacillin-tazobactam) and antifungal (liposomal amphotericin B) therapy were administered, associated with clarithromycin, according to our protocol for patients with severe pneumonia, until the availability of specific diagnosis [6]. In all cases galactomannan antigen resulted negative and antifungals were discontinued at documentation of M. pneumoniae infection. Antimycoplasma therapy was administered for 21 days and all patients survived without sequelae. In granulocytopenic cancer patients, fungal pneumonia represents a serious complication because of its high mortality. CT imaging may be not specific, since a halo sign is present very early and for a short period of time and in the subsequent days radiological features of IFD may be aspecific [7]. According to the most recent classification [8], a possible pulmonary IFD is defined by the presence of appropriate host factors in a patient with fever, respiratory symptoms, chest CT scan with dense, well-circumscribed lesions with or without a halo sign, in absence of mycological support. Even if the definitions of IFD should be used for research purposes only [8], actually they are adopted in the everyday clinical practice. The three cases we described would have fulfilled the criteria for a possible IFD, if we had not checked for M. pneumoniae infection, and it must be stressed that they represented 1/3 of cases of pneumonias that we could have classified as possible IFD. In these cases also the possibility of a polymicrobial infection, including Aspergillus, should be considered [9,10]. Our report indicates that M. pneumoniae should be included in the differential diagnosis of pneumonia in granulocytopenic children since it requires specific therapy.