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Pulmonary Malacoplakia Associated With Rhodococcus equi Infection in a Patient With AIDS* FREE TO VIEW

Myung Soo Shin, MD, FCCP; J. Allen D. Cooper, Jr., MD, FCCP; Kang-Jey Ho, MD, PhD
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*From the Departments of Radiology (Dr. Shin), Pulmonary Medicine (Dr. Cooper), and Pathology (Dr. Ho), University of Alabama School of Medicine, Birmingham, AL.



Chest. 1999;115(3):889-892. doi:10.1378/chest.115.3.889
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An AIDS patient with a cavitary lung lesion was found to have pulmonary malacoplakia associated with Rhodococcus equi infection. The diagnosis was based on the typical histologic features of transbronchial biopsy and a positive bacterial culture. All 13 reported cases of AIDS patients with pulmonary malacoplakia were associated with R equi. The recognition of this unique entity is important because of its responsiveness to therapy.

Figures in this Article

Rhodococcus equi has long been recognized as a causal agent of bronchopneumonia, primarily in foals, pigs, and a wide range of other animals.1The first reported human infection involved a patient suffering from R equi pneumonia who had been given corticosteroid therapy for chronic hepatitis in 1967.2 Since then, the great majority of human infections have occurred in patients with defects in cell-medicated immunity and who often had a history of contact with farm animals.3,,4 Since the first report of R equi infection in an AIDS patient in 1986,,5>100 cases have been recorded. R equi pulmonary infections most commonly present as a cavitary lung mass. Some of these lesions have been found to be associated with pulmonary malacoplakia.6,,7,,8,,9,,10,,11,,12

We present a 39-year-old man initially diagnosed as suffering from dermatomyositis. He was treated with immunosuppressive therapy, but subsequently tested positive for HIV. Cavitary pulmonary lesions then developed, which were proven histologically and microbiologically to be malacoplakia associated with R equi infection. Recognition of malacoplakia associated with R equi in AIDS patients is important because R equi strains are generally sensitive to antibiotic therapy.

A 39-year-old white man with a history of 50 pack-years of tobacco smoking beginning at the age of 5 years presented initially with a photosensitivity skin rash. Based on a skin biopsy done elsewhere, this was diagnosed as dermatomyositis in May 1994. The patient had no history of muscle weakness. There was no record of repeated muscle biopsy or serum creatinine phosphokinase level, but serum aspartate transaminase levels had been normal throughout his course. Due to the concern about a possible underlying malignancy, the patient was evaluated extensively with numerous screening tests for cancer with negative results. He was treated with various immunosuppressive agents (prednisone, methotrexate, and hydroxychloroquine) with moderate improvement of his rash.

Five months later, the patient started to suffer from intermittent epistaxis. In February 1995, he developed worsening shortness of breath with a dry cough, pleuritic pain over the right mid-chest, and bilateral maxillary sinusitis. He was treated with oral antibiotics, but he subsequently developed a temperature of 40°C. Chest radiography revealed a large, ill-defined round opacity with cavitations and air-fluid level in the middle lobe of the right lung (Fig 1). The patient was readmitted to another hospital. Bronchoscopy showed erythematous bronchial mucosa; bronchial brushing revealed atypical endobronchial epithelial hyperplasia, but no malignancy. Smears and culture of bronchial brushing specimens were all negative for mycobacteria. A CT scan showed a large, dense air-space opacity in the right middle lobe, multiple cavities with fluid levels, and several smaller nodular densities in both lungs (Fig 2). The patient was given IV antibiotics, but the symptoms worsened. He was then referred to the university hospital.

On admission, physical examination revealed a chronically ill-appearing, emaciated (25-kg weight loss over the past year) man with oral thrush and scaling erythematous plaques on hands, arms, elbows, knee, pretibial area, lower back, and abdomen; he had a full muscle strength of 5 throughout. Laboratory data showed a white cell count of 5,000/μL with 86% neutrophils, 11% lymphocytes, 2% monocytes, and 1% eosinophils; tests were negative for antineutrophil cytoplasmic autoantibodies, antinuclear antibodies, rheumatoid factor, and anergic purified protein derivative skin test. The HIV test was positive. His CD4 T-cell count was 40 μL. BAL fluid was negative for acid-fast bacilli, fungi, and malignancy. Bacterial culture, however, grew out R equi. Transbronchial biopsy obtained four fragments of small pale-tan soft tissue. Microscopically, the lesions were composed of sheets of plump epithelioid histiocytes with abundant eosinophilic, homogenous, or granular cytoplasm, characteristic of von Hansemann’s histiocytes. Some intra- and extracellular round, target-like calcific Michaelis-Gutmann bodies were easily identified (Fig 3). No definite organisms were detected by special stains. The histologic features are typical for malacoplakia. The patient was treated with a course of IV vancomycin for 12 days with much improvement and was followed up in an AIDS clinic. Subsequent chest radiography revealed complete resolution of the lung lesions.

Rhodococci are aerobic, Gram-positive, nonmotile, catalase-positive actinomycetes1 that form rods to extensively branched vegetative mycelium. Rhodococci are opportunistic pathogens that infect primarily immunocompromised patients.13 AIDS, organ transplant, chemotherapy, steroid therapy, and hematologic malignancy are the most common predisposing factors.13 In a great majority of cases, the primary infection site is the lung, as it was in this patient.13 Since rhodococci are frequently cultured from blood in infected patients, hematogenous spread to extrapulmonary sites seems likely, resulting in cutaneous abscess, brain abscess, and osteomyelitis.13 Other strains of rhodococci, such as R erythropolis, R rhodnii, and R rhodochrous, have also been implicated in pathogenic processes.,1

Malacoplakia is an uncommon inflammatory disorder most commonly found in the female urinary tract associated with Escherichia coli as well as other bacterial (including mycobacteria) and fungal infection.14 In 13 previously reported cases of pulmonary malacoplakia in AIDS patients, as well as in this patient, R equi was the only organism isolated.,6,,7,,8,,9,,10,,11,,12 Such a unique association between AIDS and rhodococci is worthwhile noticing.

The pathogenesis of malacoplakia is unknown, but it is thought to be an acquired disease secondary to immunosuppression.12,,15,,16,,17 The defect in the macrophage is not in the oxygen-dependent microbicidal system,15but a deficiency of 3′, 5′-guanidine monophosphate dehydrogenase, causing diminished lysosomal breakdown of the ingested organism,16,,17 has been proposed. Another possibility is that certain special constituents of R equi are undigestible by lyosomal enzymes in HIV-infected macrophages.

Malacoplakia associated with R equi infection is also found in immunocompromised patients other than AIDS patients.18,,19 For those AIDS or non-AIDS patients with R equi pneumonia, but no diagnosis of malacoplakia, the biopsied or aspirated materials should be carefully reviewed for the evidence of malacoplakia. It is possible that malacoplakia is underdiagnosed in such patients.

The initial diagnosis of dermatomyositis in this patient was questionable because the histopathology of dermatomyositis is not specific, the patient had full strength of muscles, and the serum muscle enzymes (aspartate transaminase) were never elevated. The skin rash could have been the initial manifestation of AIDS in this patient.

Since R equi-associated malacoplakia is treatable, as demonstrated in this case and other cases, the importance of its early recognition in AIDS patients should be emphasized.

Correspondence to: MS Shin, MD, Department of Radiology, 619 South 19th Street, Birmingham, AL 35233

Figure Jump LinkFigure 1.  Chest radiograph revealing a large, poorly defined, round opacity (7 × 7 × 6 cm) in the right middle lobe with cavitations and fluid levels.Grahic Jump Location
Figure Jump LinkFigure 2.  CT scan revealing a large, dense air-space opacity in the right middle lobe with multiple cavities with fluid levels and multiple smaller nodules in both lungs.Grahic Jump Location
Figure Jump LinkFigure 3.  Histology of the transbronchial biopsy specimen of the lung lesion showing sheets of plump epithelioid von Hansemann’s histiocytes and three target-like Michaelis-Gutmann bodies (arrowheads).Grahic Jump Location
Goodfellow M. Nocardia and related genera. In: Balows A, Duerden BI, eds. Topley and Wilson’s microbiology and microbial infection. Vol. 2. Systemic bacteriology. 9th ed. London: Arnold, 1998; 463–489.
 
Golub, B, Falk, G, Sprink, WW Lung abscess due toCorynebacterium equi: report of first human infection.Ann Intern Med1967;66,1174-1177. [PubMed]
 
Prescott, JF Rhodococcus equi: an animal and human pathogen.Clin Microbiol Rev1991;4,20-34. [PubMed]
 
McNeil, MM, Brown, JM The medically important aerobic actinomycetes: epidemiology and microbiology.Clin Microbiol Rev1994;7,357-417. [PubMed]
 
Samies, JH, Hathaway, BN, Echols, RM, et al Lung abscess due toCorynebacterium equi: report of the first case in a patient with acquired immunodeficiency syndrome.Am J Med1986;80,685-688. [PubMed] [CrossRef]
 
Schwartz, DA, Ogden, PO, Blumberg, HM, et al Pulmonary malakoplakia in a patient with the acquired immunodeficiency syndrome: differential diagnostic considerations.Arch Pathol Lab Med1990;114,1267-1272. [PubMed]
 
Scannell, KA, Portoni, EJ, Finkle, HI, et al Pulmonary malacoplakia andRhodococcus equiinfection in a patient with AIDS.Chest1990;97,1000-1001. [PubMed]
 
Russell, GM, Mills, AE Pulmonary malakoplakia related toRhodococcus equioccurring in the acquired immunodeficiency syndrome [letter].Med J Aust1994;160,308-309
 
Kwon, KY, Colby, TV Rhodococcus equipneumonia and pulmonary malakoplakia in acquired immunodeficiency syndrome: pathologic features.Arch Pathol Lab Med1994;118,744-748. [PubMed]
 
Calore, EE, Vazquez, CR, Perez, NM, et al Empyema with malakoplakic-like lesions byRhodococcus equias a presentation of HIV infection.Pathologica1995;87,525-527. [PubMed]
 
Sughayer, M, Ali, SZ, Erozan, YS, et al Pulmonary malacoplakia associated withRhodococcus equiinfection in an AIDS patient: report of a case with diagnosis by fine needle aspiration.Acta Cytol1997;41,507-512. [PubMed]
 
Yuoh, G, Hove, MG, Wen, J, et al Pulmonary malakoplakia in acquired immunodeficiency syndrome: an ultrastructural study of morphogenesis of Michaelis-Gutmann bodies.Mod Pathol1996;9,476-483. [PubMed]
 
Lasky, JA, Pulkingham, N, Powers, MA, et al Rhodococcus equicausing human pulmonary infection: review of 29 cases.South Med J1991;84,1217-1220. [PubMed]
 
Damjanov, I, Katz, SM Malakoplakia.Pathol Annu1981;16,103-126. [PubMed]
 
Schreiber, AG, Maderazo, EG Leukocytic function in malakoplakia.Arch Pathol Lab Med1978;102,534-537. [PubMed]
 
Biggar, WD, Keating, A, Brear, RA Malakoplakia: evidence for an acquired disease secondary to immunosuppression.Transplantation1981;31,109-112. [PubMed]
 
Shabtai, M, Anaise, D, Frei, L, et al Malakoplakia in renal transplantation: an expression of altered tissue reactivity under immunosuppression.Transplant Proc1989;21,3725-3727. [PubMed]
 
van Hoeven, KH, Dookhan, DB, Petersen, RO Cytologic features of pulmonary malakoplakia related toRhodococcus equiin an immunocompromised host.Diagn Cytopathol1996;15,325-328. [PubMed]
 
Lambert, C, Gansler, T, Mansour, KA, et al Pulmonary malakoplakia diagnosed by fine needle aspiration: a case report.Acta Cytol1997;41,1833-1838. [PubMed]
 

Figures

Figure Jump LinkFigure 1.  Chest radiograph revealing a large, poorly defined, round opacity (7 × 7 × 6 cm) in the right middle lobe with cavitations and fluid levels.Grahic Jump Location
Figure Jump LinkFigure 2.  CT scan revealing a large, dense air-space opacity in the right middle lobe with multiple cavities with fluid levels and multiple smaller nodules in both lungs.Grahic Jump Location
Figure Jump LinkFigure 3.  Histology of the transbronchial biopsy specimen of the lung lesion showing sheets of plump epithelioid von Hansemann’s histiocytes and three target-like Michaelis-Gutmann bodies (arrowheads).Grahic Jump Location

Tables

References

Goodfellow M. Nocardia and related genera. In: Balows A, Duerden BI, eds. Topley and Wilson’s microbiology and microbial infection. Vol. 2. Systemic bacteriology. 9th ed. London: Arnold, 1998; 463–489.
 
Golub, B, Falk, G, Sprink, WW Lung abscess due toCorynebacterium equi: report of first human infection.Ann Intern Med1967;66,1174-1177. [PubMed]
 
Prescott, JF Rhodococcus equi: an animal and human pathogen.Clin Microbiol Rev1991;4,20-34. [PubMed]
 
McNeil, MM, Brown, JM The medically important aerobic actinomycetes: epidemiology and microbiology.Clin Microbiol Rev1994;7,357-417. [PubMed]
 
Samies, JH, Hathaway, BN, Echols, RM, et al Lung abscess due toCorynebacterium equi: report of the first case in a patient with acquired immunodeficiency syndrome.Am J Med1986;80,685-688. [PubMed] [CrossRef]
 
Schwartz, DA, Ogden, PO, Blumberg, HM, et al Pulmonary malakoplakia in a patient with the acquired immunodeficiency syndrome: differential diagnostic considerations.Arch Pathol Lab Med1990;114,1267-1272. [PubMed]
 
Scannell, KA, Portoni, EJ, Finkle, HI, et al Pulmonary malacoplakia andRhodococcus equiinfection in a patient with AIDS.Chest1990;97,1000-1001. [PubMed]
 
Russell, GM, Mills, AE Pulmonary malakoplakia related toRhodococcus equioccurring in the acquired immunodeficiency syndrome [letter].Med J Aust1994;160,308-309
 
Kwon, KY, Colby, TV Rhodococcus equipneumonia and pulmonary malakoplakia in acquired immunodeficiency syndrome: pathologic features.Arch Pathol Lab Med1994;118,744-748. [PubMed]
 
Calore, EE, Vazquez, CR, Perez, NM, et al Empyema with malakoplakic-like lesions byRhodococcus equias a presentation of HIV infection.Pathologica1995;87,525-527. [PubMed]
 
Sughayer, M, Ali, SZ, Erozan, YS, et al Pulmonary malacoplakia associated withRhodococcus equiinfection in an AIDS patient: report of a case with diagnosis by fine needle aspiration.Acta Cytol1997;41,507-512. [PubMed]
 
Yuoh, G, Hove, MG, Wen, J, et al Pulmonary malakoplakia in acquired immunodeficiency syndrome: an ultrastructural study of morphogenesis of Michaelis-Gutmann bodies.Mod Pathol1996;9,476-483. [PubMed]
 
Lasky, JA, Pulkingham, N, Powers, MA, et al Rhodococcus equicausing human pulmonary infection: review of 29 cases.South Med J1991;84,1217-1220. [PubMed]
 
Damjanov, I, Katz, SM Malakoplakia.Pathol Annu1981;16,103-126. [PubMed]
 
Schreiber, AG, Maderazo, EG Leukocytic function in malakoplakia.Arch Pathol Lab Med1978;102,534-537. [PubMed]
 
Biggar, WD, Keating, A, Brear, RA Malakoplakia: evidence for an acquired disease secondary to immunosuppression.Transplantation1981;31,109-112. [PubMed]
 
Shabtai, M, Anaise, D, Frei, L, et al Malakoplakia in renal transplantation: an expression of altered tissue reactivity under immunosuppression.Transplant Proc1989;21,3725-3727. [PubMed]
 
van Hoeven, KH, Dookhan, DB, Petersen, RO Cytologic features of pulmonary malakoplakia related toRhodococcus equiin an immunocompromised host.Diagn Cytopathol1996;15,325-328. [PubMed]
 
Lambert, C, Gansler, T, Mansour, KA, et al Pulmonary malakoplakia diagnosed by fine needle aspiration: a case report.Acta Cytol1997;41,1833-1838. [PubMed]
 
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