Pulmonary malacoplakia associated with Rhodococcus equi infection in a patient with AIDS

Malakoplakia of urinary bladde: 3 cases reports and review

OBJECTIVE

This study aims to explore the clinical diagnosis and treatment methods of bladder malakoplakia (MUB) to enhance the understanding of the disease.

METHODS

A retrospective analysis of the diagnosis and treatment processes of three cases of MUB treated in our department was conducted. Relevant literature from both domestic and international sources was reviewed to provide a comprehensive analysis.

RESULTS

All three patients underwent transurethral resection of bladder lesions combined with antibiotic therapy, and two of them received transurethral instillation of gemcitabine. There were two cases with two recurrences each, and one case with four recurrences, with the latter also concurrently presenting with unilateral ureteral malakoplakia. Postoperative pathology confirmed MUB in all three cases. Close follow-up revealed no significant recurrence in the patients.

CONCLUSION

The effective diagnosis rate is increased by conducting multiple deep, repetitive, and randomly selected live tissue examinations. The definitive diagnosis of MUB relies on pathological histological examination. Treatment involving a combination of antibiotics and transurethral resection of bladder lesions proves to be effective. Exploring the use of bladder instillation of gemcitabine widens the spectrum of MUB treatment methods.

Malakoplakia of the gastrointestinal tract: clinicopathologic analysis of 23 cases

Background

Malakoplakia is an uncommon, tumor-like inflammatory disease characterized by impaired histiocytes that are unable to completely digest phagocytized bacteria. The genitourinary tract is the most common site of involvement, however, cases have also been described in the gastrointestinal tract, suggesting that it is the second most common site of involvement. This study investigates the clinical and histologic features of malakoplakia in the gastrointestinal tract.

Case presentation

For 23 gastrointestinal specimens (biopsies and resections) from patients with a pathologic diagnosis of malakoplakia, we recorded the gender, age, location, primary diagnosis, endoscopic or surgical indication, endoscopic/gross impression and immune status (immunocompromised vs. immunocompetent).

Conclusion

Malakoplakia occurred throughout the length of the gastrointestinal tract with most of the cases located in the sigmoid colon and rectum (n = 10); other sites included the transverse and descending colon (n = 4), stomach/gastroesophageal junction (n = 4), appendix (n = 2), cecum (n = 1), small bowel (n = 1), and the peri-anal area (n = 1). Endoscopically, these lesions most commonly appeared as polyps (n = 10) or masses (n = 5), other clinical endoscopic impressions varied from a thickened area/fibrosis to mucosal erythema. Most patients were immunocompromised due to a disease state (e.g. organ transplantation, cancer diagnosis, autoimmune condition) and/or medication effect. Eight patients with malakoplakia were on immunosuppressive medications (8/23, 35%). Common immunosuppressed disease states included cancer (n = 9), autoimmune disease (n = 5), status post organ transplantation (n = 4), diabetes (n = 5), infection/sepsis (n = 3), and HIV/AIDS (n = 1). Some patients had multiple co-morbidities (i.e. diabetes and organ transplant). Twenty-one patients with malakoplakia were in an immunosuppressive state (21/23, 91%).

Pulmonary Malakoplakia by Rhodococcus equi in an HIV-Infected Patient in Mexico: A Case Report

Background

Rhodococcus equi-related pulmonary malakoplakia is a rare condition with few reported cases; hereby, we present a case associated with advanced human immunodeficiency virus (HIV) infection, and thus far to our knowledge, the first report in Mexico. It is estimated that approximately 10% of the infections occur in immunocompetent patients, whereas the rest are immune deficient, targeting virtually any organ. Histologically, malakoplakia is characterized by the buildup of infiltrated inflammatory tissue as a consequence of the gathering of histiocytes embedded with concentric inclusions. The diagnosis relies on the cultures and the susceptibility testing as well as the pathologic findings compatible with the disease. Case Presentation. We present a 25-year-old male patient with persistent nonproductive cough for over a year and with weight loss, who comes to the emergency department with recent fever, swollen and tender lymph nodes, and hemoptysis. The patient gets diagnosed and treated for Rhodococcus equi-related pulmonary malakoplakia.

Conclusion

Knowing the involvement of Rhodococcus in HIV is fundamental for the diagnosis and optimal treatment, which although unknown, a combination of antibiotics with intracellular penetration, on-time resection, and a proper immune reconstitution represents the best approach. Prognosis varies with mortality rates from 34% to 54%.

Cutaneous malakoplakia presenting as a groin swelling and graft failure

Malakoplakia (from the Greek malakos, 'soft' and plakos 'plaque') is a granulomatous inflammatory condition, commonly presenting as a plaque in the genitourinary system, but has been shown to affect a wide variety of structures including the skin. Presentation is varied and a high degree of clinical suspicion is needed to make a diagnosis. We report a case of cutaneous malakoplakia presenting as an inguinal swelling in a 48-year-old kidney transplant patient with temporally associated graft dysfunction. New groin swelling in an immunosuppressed patient often prompts investigation centred on a malignant cause. While this is often appropriate, less common infectious and inflammatory causes should be considered. This case highlights the importance of thorough workup and investigation, including histopathology, in immunosuppressed cohorts and acts as a reminder that less common and more complex diagnoses warrant consideration in this group.

Malakoplakia of the thyroid gland: a case report and review of literature

Malakoplakia is a rare granulomatous disease that most commonly occurs in the urinary tract. It is characterized by sheets of histiocytes with granular basophilic inclusions and Michaelis-Gutmann bodies. We present an exceedingly rare case of malakoplakia of the thyroid in a 54-year-old Caucasian woman on immunosuppressive therapy for renal transplant performed in 1994.

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.

Infectious pseudotumors: red herrings in head and neck pathology

Infectious pseudotumors are tumor-like growths caused by specific microbial organisms. Proliferating histiocytes in these lesions may show atypical cytology with nuclear pleomorphism and increased mitotic activity, erroneously suggestive of malignancies including carcinoma, sarcoma, and lymphoma. Specific and nonspecific immunohistochemical staining profiles may lead to the consideration of a wide range of benign and malignant neoplastic processes. Two such cases are reported. The first is an obstructive endotracheal mass in an AIDS patient caused by Rhodococcus equi infection. The proliferating histiocyes were cytologically atypical with deeply eosinophlic granular cytoplasm leading to the consideration of oncocytic carcinoma, Hurthle cell carcinoma, and pleomorphic rhabdomyosarcoma. The second case is a nasal mass with a microscopic and immunohistochemical profile suggestive of chordoma and paraganglioma. Special microbial stains revealed intracellular bacilli consistent with Klebsiella rhinoscleromatis. In both cases, microbial virulence factors affecting phagocytosis prolonged their intracellular survival and resulted in active histiocytic proliferation. It is of importance that the surgical pathologist be conscious that some infectious processes can clinically and microscopically mimic malignant neoplasms. Accurately identifying these lesions and the specific causative agent is of particular significance since they can be successfully treated with antibiotics.

Pseudotumor of the tracheal-laryngeal junction with unusual morphologic features caused by Rhodococcus equi infection

Infectious pseudotumors are unusual proliferations of histiocytes in response to certain microbial organisms. Occasionally this process may involve large airways, producing a mass lesion that may cause respiratory obstruction. Infectious pseudotumors can be confused with malignancy in their radiologic appearance and clinical presentation. We present a case of an aggressive endotracheal pseudotumor associated with Rhodococcus equi infection in a patient with advanced HIV disease. Microscopically, the lesion was composed of sheets of epithelioid histiocytes with large, strongly eosinophilic intra-cytoplasmic granules and features of malakoplakia. In this report, we review the literature of these unusual lesions and compare them to cases of conventional malakoplakia involving the large airways. We also explore the pathogenetic mechanisms that may contribute to the distinctive histologic appearance of Rhodococcus-associated pseudotumors.

Rhodococcus equi infection in HIV-infected individuals: case reports and review of the literature

Rhodococcus equi is a gram-positive, coryneform bacterium that causes zoonotic infection mainly in horses and foals. It sometimes affects humans presenting as cavitary pneumonia. Immunocompromised patients, including HIV-infected patients, are more susceptible to R. equi infection. We present 10 cases of R. equi infection in HIV-positive patients admitted to our institute from 1991 to June 2008. Moreover, we have reviewed 272 cases of R. equi infection in HIV-infected persons, published from 1986 through 2008. With respect to the literature data, the R. equi strains isolated in our case series showed lower sensitivity to ceftriaxone, amoxicillin/clavulanic acid, and cotrimoxazole. Prompt diagnosis, early initiation of antiretroviral treatment and combined antimicrobial treatment seem to be effective to eradicate the infection and to improve the outcome.

Histiocytic lesions and proliferations in the lung

Pulmonary lesions encountered by the pathologist in which histiocytes are the dominant finding histologically are reviewed. Lesions discussed include neoplasms of histiocytes and nonneoplastic processes. The nonneoplastic processes are divided into those that present as nodular histiocytic proliferations in the lung, those that present as diffuse proliferations of histiocytes in the lung, and those with a mixed pattern. Entities discussed include pulmonary Langerhans' cell histiocytosis, pneumonoconioses, infections, diffuse panbronchiolitis, crystal storing histiocytosis, respiratory bronchiolitis, alveolar hemorrhage, eosinophilic pneumonia, obstructive pneumonia, exogenous lipoid pneumonia, some drug reactions, and some metabolic/storage diseases. Entities of uncertain histogenesis, including Rosai-Dorfman disease and Erdheim-Chester disease, are also discussed. Qualitative features of the histiocytes are addressed, including the presence of foreign dust, hemosiderin, foamy change, and histiocytes showing features of Langerhans' cells.

Malakoplakia of the prostate on needle core biopsy: a case report and review of the literature

Malakoplakia is a rare inflammatory disorder that results from an infectious process and that may be associated with immunosuppression. It most often occurs in the genitourinary tract; however, isolated cases have been reported in many other organs, including colon, stomach, lung, liver, bone, uterus, and skin. In the bladder, which is the most common site of involvement, it may be mistaken for malignancy on cystoscopic examination or computerized topography scan. Gram-negative bacteria such as Escherichia coli and Klebsiella pneumonia are often isolated from malakoplakia lesions, although other less common bacteria such as Rhodococcus equi may also be found. This is a case report of prostatic malakoplakia diagnosed on needle core biopsy from a patient suspected to harbor a malignancy.

Malakoplakia Outside the Urinary Tract

Context.—Malakoplakia is a rare granulomatous disease that occurs commonly in the urinary tract. Histologically, it is defined by sheets of histiocytes (Hansemann cells) with accumulation of granular basophilic periodic acid-Schiff– positive, diastase-resistant inclusions and calcified Michaelis-Gutmann bodies, which are pathognomonic but not necessary for diagnosis. In addition to the urinary tract, malakoplakia has been reported in other organs, including the gastrointestinal tract, central nervous system, female genital tract, and the tongue.

Objectives.—To review the literature of reported sites of malakoplakia outside the urinary tract and their variable clinical presentations, and to discuss the main diagnostic features and differential diagnoses of malakoplakia. The pathogenesis and possible etiologic factors are also presented.

Data Sources.—Data for this work were collected from the published literature, textbooks, and the Internet.

Conclusions.—It is important to be aware of the existence of this entity in abnormal locations. In many situations, malignancy can be mimicked, especially when the lesion is ulcerated and is accompanied by lymph node involvement. Misinterpreting large, rapidly growing nodules of malakoplakia as tumor might lead to overstaging. Pathologists should be also aware of the possibility of malakoplakia coexisting with other lesions, such as tuberculosis and carcinoma, in the same specimen.

Malacoplakia of the cranium and cerebrum in a human immunodeficiency virus-infected man. Case report

Malacoplakia is a rare chronic inflammatory disease associated with infection and immunosuppression, and very few occurrences have been reported in the cerebrum. The authors describe the case of a 41-year-old man with advanced human immunodeficiency virus (HIV) infection who presented with a very aggressive malacoplakia lesion that had extended through the scalp, temporalis muscle, skull bone, and deep through the dura mater into the superior sagittal sinus and adjacent brain. Pathological examination revealed sheets of histiocytes invading these structures, and macrophages containing numerous round bodies known as Michaelis-Guttmann bodies, pathognomic for malacoplakia. Because of the rarity of this phenomenon, appropriate treatment and management of malacoplakia are speculative. A complete resection of the lesion, antibiotic therapy, and treatment of his underlying HIV infection had a salutary effect, with the patient faring well more than 9 months postoperatively.

Pulmonary Malakoplakia Coexistent with Tuberculosis of the Hilar Lymph Node Mimicking Malignancy

Pulmonary malakoplakia is a disease that is difficult to diagnose because its symptoms vary from those mimicking bronchogenic carcinoma to pneumonitis-like tuberculous infections. Malakoplakia is an unusual inflammatory condition characterized by the accumulation of macrophages with diagnostic Michaelis-Gutmann bodies. In this study, an immunocompromised patient with a tumor mass in the upper lobe of the right lung coexisting with hilar node enlargement is presented. A thoracoscopic biopsy revealed pulmonary malakoplakia with tuberculosis of the hilar lymph node. Microbiologic cultures were positive for acid-fast positive bacilli from the hilar node specimen, and negative for any other microorganisms such as Rhodococcus equi, but positive for Escherichia coli from the lung specimen. The significance of these findings and the coincidental association between malakoplakia and tuberculosis are discussed.

In situ hybridization for detection of nocardial 16S rRNA: reactivity within intracellular inclusions in experimentally infected cynomolgus monkeys--and in Lewy body-containing human brain specimens

Our previous studies found that experimental infection of BALB/c mice with the Gram-positive bacterium Nocardia asteroides induced a parkinsonian-type syndrome with levodopa-responsive movement abnormalities, loss of nigrostriatal dopaminergic neurons, depletion of striatal dopamine, and intraneuronal inclusions in the substantia nigra (SN) with an appearance similar to Lewy bodies. In the present study, an in situ hybridization technique was developed to detect nocardial 16S ribosomal RNA (rRNA), using a Nocardia-specific probe (B77). Cerebral cortical specimens from cynomolgus monkeys were examined for the presence of nocardial RNA 48 h, 3.5 months, and 1 year after experimental infection with N. asteroides. Hybridization reactions were detected within Nocardia-like structures 48 h after infection and within intracellular inclusion bodies (immunoreactive for alpha-synuclein and ubiquitin) in one of two 3.5-month-infected monkeys. The in situ hybridization procedure was then applied in a blinded fashion to 24 human SN specimens with Lewy bodies and 11 human SN specimens without Lewy bodies (including five normal controls). Hybridization reactions were detected in nine Lewy body-containing specimens and none of the others. Reactivity was limited to inclusions with the appearance of Lewy bodies, with the exception of one specimen in which intracellular reactivity was also observed in Nocardia-like structures. These results suggest a possible association between Nocardia and neurodegenerative disorders in which Lewy bodies are present.

Malakoplakia in association with colorectal carcinoma: a series of four cases

AIMS

Malakoplakia is a characteristic inflammatory condition which is usually seen in the urogenital tract. Gastrointestinal malakoplakia is seen in association with a variety of conditions such as ulcerative colitis, diverticular disease, adenomatous polyps and carcinoma. The purpose of this paper is to report four additional cases of colorectal cancer associated with malakoplakia and review the literature on this association.

METHODS

All specimens were colectomies for cancer. Routine handling of the specimen with lymph node harvesting was performed. In addition to H&E stains, PAS, Perls' Prussian Blue and von Kossa stains were performed.

RESULTS

Three of the cases were encountered in males and the patients ranged in age from 55 to 64 years. One case each occurred in the caecum/ascending colon and descending colon, while the remaining two were located in the rectum. All four cases were Dukes' stage B tumours. Furthermore, all four cases had spread to pericolic fat and two had perforated. Microscopic examination showed the malakoplakia to be present at the infiltrating edge of the tumours. The draining lymph nodes were involved by malakoplakia to varying degrees in all cases.

CONCLUSIONS

From this series and the literature review, malakoplakia associated with colorectal cancer tends to occur in elderly males in the rectum. The malakoplakia is found at the infiltrating front of the tumour and is not admixed with the neoplastic glands. Although lymph node involvement by malakoplakia has been reported only once previously, all four cases in this series showed evidence of involvement. The association does not appear to have any prognostic significance.

Rhodococcus equi pneumonia in a patient with human immunodeficiency virus: case report and review

Rhodococcus equi is a facultative, intracellular, gram-positive coccobacillus increasingly reported as an opportunistic pathogen in patients positive for human immunodeficiency virus (HIV). An HIV-positive man developed R. equi pneumonia and sepsis. He failed to improve despite surgical drainage of localized infection and many empiric antibiotics. Time-kill studies of R. equi isolated from the patient were performed against various antimicrobial agents to optimize therapy. Levofloxacin seemed to offer excellent in vitro bactericidal activity. Antagonism was observed with certain antibiotic combinations. Our anecdotal case report suggests that fluoroquinolones such as levofloxacin may offer superior efficacy to standard therapy in rhodococcal infections; their clinical utility deserves further investigation. In view of potential antagonism, prospective susceptibility testing for various drugs and drug combinations should be considered when clinically indicated.

Rhodococcus equi and cytomegalovirus pneumonia in a renal transplant patient: diagnosis by fine-needle aspiration biopsy

Rhodococcus equi is a common cause of pneumonia in animals. Human infection is rare. Increasing number of cases are being reported in immunosuppressed individuals mostly associated with HIV infection, but also in solid organ transplant recipients and leukemia/lymphoma patients. We report on an adult male who developed pneumonia and gastroenteritis 4 mo after receiving a renal transplant. CT scan of the lungs showed a dominant 2.5-cm upper lobe lung mass and smaller bilateral nodules. He underwent a diagnostic bronchoscopy with fine-needle aspiration biopsy of the largest lung nodule. Smears showed histiocytic granulomatous inflammation, foamy macrophages, and acute inflammatory exudate. Scattered foamy macrophages displayed intracellular coccobacilli identifiable on Diff-Quik stain. A few cells with changes suggestive of viral inclusions were identified. Cytomegalovirus (CMV) immunostain was positive in the cell block sections. Lung cultures grew R. equi. To the best of our knowledge, this is the first report of coinfection with R. equi and CMV.