Pulmonary malacoplakia at early stage: use of polymerase chain reaction for detection of Rhodococcus equi.
Malacoplakia is a rare inflammatory condition characterized by the accumulation of benign macrophages associated with pathognomonic Michaelis-Gutmann bodies (MGBs). It is usually found in the genito-urinary tract, and has been associated with immunocompromised states. In this short report, we present 5 patients with pulmonary nodules clinically suspicious for primary or metastatic lung cancer. The histologic examination of the surgical specimens revealed a nonspecific granulomatous chronic disease, and despite the paucity of classical MGBs, a pulmonary malacoplakia was suspected. In all cases the opportunistic pathogen Rhodococcus equi (R. equi) was identified by 16S rRNA gene sequence analysis, leading to the final pathological diagnosis of malacoplakia. We conclude that pulmonary malacoplakia associated with R. equi is a rare disease affecting also immunocompetent patients. The pathogenesis and the diagnostic problems are discussed. Since infection by R. equi is treatable, the importance of its early recognition should be emphasized.
Department of Pathology, Haematology, Microbiology and Molecular Diagnosis, Catholic University of Sacred Heart, Rome, Italy. amule@rm.unicatt.it
A
A
Mulè
G
G
Petrone
A
A
Santoro
M
M
Sanguinetti
E
E
Meacci
A
A
Coli
S
S
Margaritora
D000193:Actinomycetales Infections / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology / Q000601:surgery; D000368:Aged; D044963:Biopsy, Fine-Needle; D004269:DNA, Bacterial / Q000032:analysis*; D004275:DNA, Ribosomal / Q000032:analysis*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008287:Malacoplakia / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D016133:Polymerase Chain Reaction; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012141:Respiratory Tract Infections / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology / Q000601:surgery; D016929:Rhodococcus equi / Q000145:classification / Q000235:genetics*; D021521:Ribotyping / Q000379:methods*; D014057:Tomography, X-Ray Computed
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S