Pulmonary infections in immunocompromised hosts: the importance of correlating the conventional radiologic appearance with the clinical setting

Imaging Approach to Pulmonary Infections in the Immunocompromised Patient

Pulmonary infections are the major cause of morbidity and mortality in immunocompromised patients and almost one-third of intensive care unit patients with pulmonary infections belong to the immunocompromised category. Multiple organisms may simultaneously infect an immunocompromised patient and the overwhelming burden of mixed infections further predisposes critically ill patients to acute hypoxemic respiratory failure. Notwithstanding that lung ultrasound is coming into vogue, the primary imaging investigation is a chest radiograph, followed by thoracic CT scan. This review based on our experience at tertiary care teaching hospitals provides insights into the spectrum of imaging features of various pulmonary infections occurring in immunocompromised patients. This review is unique as, firstly, the imaging spectrum described by us is categorized on basis of the etiological infective agent, comprehensively and emphatically correlated with the clinical setting of the patient. Secondly, a characteristic imaging pattern is emphasized in the clinical setting-imaging-pattern conglomerate, to highlight the most likely diagnosis possible in such a combination. Thirdly, the simulating conditions for a relevant differential diagnosis are discussed in each section. Fourthly, not only are the specific diagnostic and tissue sampling techniques for confirmation of the suspected etiological agent described, but the recommended pharmaco-therapeutic agents are also enumerated, so as to provide a more robust insight to the radiologist. Last but not the least, we summarize and conclude with a diagnostic algorithm, derived by us from the characteristic illustrative cases. The proposed algorithm, illustrated as a flowchart, emphasizes a diagnostic imaging approach comprising: correlation of the imaging pattern with clinical setting and with associated abnormalities in the thorax and in other organs/systems, which is comprehensively analyzed in arriving at the most likely diagnosis. Since a rapid evaluation and emergent management of such patients is of pressing concern not only to the radiologist, but also for the general physicians, pulmonologists, critical care specialists, oncologists and transplant surgery teams, we believe our review is very informative to a wide spectrum reader audience.

Percutaneous transthoracic needle biopsies in immunocompromised hosts with suspicious pulmonary infection: diagnostic yields and complications

BACKGROUND

Pulmonary infection is a major cause of morbidity and mortality in immunocompromised patients, in whom diagnostic yields of cone-beam computed tomography (CBCT)-guided percutaneous transthoracic needle biopsies (PTNBs) have not been evaluated so far.

PURPOSE

To evaluate diagnostic yields and complications of CBCT-guided PTNBs in immunocompromised patients.

MATERIAL AND METHODS

From January 2015 to January 2018, 43 patients (25 men, 18 women; mean age 54.1 ± 16.4 years) who were suspected of having pulmonary infections were included in this retrospective study. Electronic medical records and radiologic studies were reviewed, including the underlying medical status, information on target lesions, PTNB procedural factors, and pathologic results. Logistic regression was performed to explore factors related with post-PTNB complications.

RESULTS

Among 43 patients, specific causative organisms or family of organisms were identified by PTNBs in 16 patients (37.2%). The most common causative organism was fungus (10/16, 62.5%), while bacterial infection was pathologically proven only in one patient (6.3%). Clinically significant change in management occurred in 12 of 43 patients (27.9%). Post-PTNB complications developed in 12 patients (27.9%; pneumothorax [n = 6] and hemoptysis [n = 6]) without PTNB-related mortality. Lower lobar location (odds ratio [OR] = 0.07, P = 0.006) was related with post-PTNB pneumothorax, while lower platelet counts (≤127 × 10³/µL) were associated with post-PTNB hemoptysis (OR = 9.82, P = 0.025).

CONCLUSION

CBCT-guided PTNBs revealed microbiological pathogens in 37.2% of immunocompromised patients and led to subsequent clinical actions in 27.9% of patients. Post-PTNB complications occurred in 27.9% of patients, and it might be necessary to perform PTNBs more carefully in immunocompromised patients with lower platelet counts.

Isolation and identification of Aspergillus fumigatus from Immunocompromised patients in AL- Najaf Province

The present study was conducted to isolation and identification of Aspergillus fumigatus. Isolated from immunocompromised patients with (Diabetes, Cancer) by different identification methods including direct examination, laboratory culture and electron microscopy. During the period from (July to September 2016), a total of 50 swab were collected from immunocompromised patients with attending to the in AL- Sadder Medical City (the Center for Diabetes and Endocrinology) and (Euphrates middle Center for cancer diseases). In AL-Najaf Governorate, the samples were collected as following: 30 swab from the eyes of cancer patients who were suffering from prostate, leukemia, stomach and intestines cancer, also 20 swabs from the ears of diabetic patients. The percentage of female to male was as following, 29 females (58%) males and 21 (42%). In this study, the results show that the incidence of aspergillosis in women was higher than the male. The results of the present study reveal that the prevalence of aspergillosis from patient with cancer was more than diabetes patients which was 18 (66.66%) and 9 (33.33%), respectively.

Chest complications in immunocompromised patients without acquired immunodeficiency syndrome (AIDS): differentiation between infectious and non-infectious diseases using high-resolution CT findings

AIM

To differentiate between infectious and non-infectious diseases occurring in immunocompromised patients without acquired immunodeficiency syndrome (AIDS) using high-resolution computed tomography (HRCT).

MATERIALS AND METHODS

HRCT images of 555 patients with chest complications were reviewed retrospectively. Infectious diseases (n=341) included bacterial pneumonia (n=123), fungal infection (n=80), septic emboli (n=11), tuberculosis (n=15), pneumocystis pneumonia (n=101), and cytomegalovirus pneumonia (n=11), while non-infectious diseases (n=214) included drug toxicity (n=84), infiltration of underlying diseases (n=83), idiopathic pneumonia syndrome (n=34), diffuse alveolar haemorrhage (n=8), and pulmonary oedema (n=5). Lung parenchymal abnormalities were compared between the two groups using the χ² test and multiple logistic regression analysis.

RESULTS

The χ2 test results showed significant differences in many HRCT findings between the two groups. Multiple logistic regression analysis results indicated the presence of nodules with a halo and the absence of interlobular septal (ILS) thickening were the significant indicators that could differentiate infectious from non-infectious diseases. ILS thickening was generally less frequent among most infectious diseases and more frequent among most non-infectious diseases, with a good odds ratio (7.887, p<0.001). The sensitivity and accuracy for infectious diseases in the absence of ILS thickening were better (70% and 73%, respectively) than those of nodules with a halo (19% and 48%, respectively), while the specificity in the nodules with a halo was better (93%) than that of ILS thickening (78%).

CONCLUSIONS

The presence of nodules with a halo or the absence of ILS thickening tends to suggest infectious disease. Specifically, ILS thickening seems to be a more reliable indicator.

Chemotherapy-induced pulmonary complications in cancer: Significance of clinicoradiological correlation

Chemotherapy while revolutionizing cancer management by improving survival and quality of life; is also associated with several adverse effects. Lung is the most common organ affected in chemotherapy-related complications, due to either drug toxicity or more commonly due to infections caused by immunosuppression and less commonly due to immune-mediated injury. Radiology, when used in combination with clinical and lab data, can help reach the specific diagnosis or narrow down the differentials. The common radiological patterns of drug toxicity include pulmonary interstitial and airway infiltrates, diffuse alveolar damage, nonspecific interstitial pneumonia, eosinophilic pneumonia, cryptogenic organizing pneumonia, pulmonary hemorrhage, edema and hypertension. Cancer patients are immunosuppressed due to the underlying malignancy itself or due to therapy and are prone to a gamut of opportunistic infections including viral, bacterial, fungal and mycobacterial pathogens. Immune reconstitution inflammatory syndrome (IRIS), a well-known complication in HIV, is now being increasingly recognized in non-HIV patients with immunosuppression. Engraftment syndrome is specifically seen following hematopoietic stem cell transplant during neutrophil recovery phase. Pulmonary involvement is frequent, causing a radiological picture of noncardiogenic pulmonary edema. Thus, radiology in combination with clinical background and lab parameters helps in detecting and differentiating various causes of pulmonary complications. This approach can help alter potentially toxic treatment and initiate early treatment depending on the diagnosis.

Antifungal use in the surgical ICU patient

PURPOSE OF REVIEW

The successful treatment of surgical fungal infections depends of a timely and adequate source control alongside with the use of prompt systemic antifungals. The main challenge of antifungal use in critically ill surgical patients is to find a balance between rational versus indiscriminate use in order to accomplish an antifungal stewardship program.

RECENT FINDINGS

Surgical fungal infections represent an important burden in the daily clinical activity in many ICUs. The efficacy of the available antifungal drugs has not been adequately assessed in randomized controlled trials with surgical fungal infections in ICU patients. Most clinical experience is limited to case reports or uncontrolled case series. Due to the lack of adequate scientific evidence to assess the role of the different antifungals in surgical ICU patients, it is usually suggested to follow the recommendations for invasive candidiasis and candidemia.

SUMMARY

Antifungal use in the surgical patients admitted to an ICU is a complex matter and there are several elements to consider like the presence of septic shock and multiorgan failure, local epidemiology and antifungal resistance, among others. The proper use of antifungals alongside early recognition and prompt source control, are critical factors for improved outcomes.

Infection in Immunocompromised Hosts: Imaging

Immunocompromised patients are encountered with increasing frequency in clinical practice. In addition to the acquired immunodeficiency syndrome (AIDS), therapy for malignant disease, and immune suppression for solid organ transplants, patients are now rendered immunosuppressed by advances in treatment for a wide variety of autoimmune diseases. The number of possible infecting organisms can be bewildering. Recognition of the type of immune defect and the duration and depth of immunosuppression (particularly in hematopoietic and solid organ transplants) can help generate a differential diagnosis. Radiologic imaging plays an important role in the detection and diagnosis of chest complications occurring in immunocompromised patients; however, chest radiography alone seldom provides adequate sensitivity and specificity. High-resolution computed tomography (CT) can provide better sensitivity and specificity, but even CT findings may be nonspecific findings unless considered in conjunction with the clinical context. Combination of CT pattern, clinical setting, and immunologic status provides the best chance for an accurate diagnosis. In this article, CT findings have been divided into 4 patterns: focal consolidation, nodules/masses, small/micronodules, and diffuse ground-glass attenuation/consolidation. Differential diagnoses are suggested for each pattern, adjusted for both AIDS and non-AIDS immunosuppressed patients.

Imaging of Pulmonary Infections

Pulmonary infections have always been a cause of high morbidity and mortality, particularly in the pediatric and geriatric population and in immunocompromised hosts [1]. Pulmonary infections have various etiologies and have variegated patterns on radiographs and computed tomography (CT). Imaging plays an important role in the initial diagnosis and follow-up of various lung infections. Radiographs can be normal or non-specific during the initial evaluation, and CT findings may be more definitive. CT not only helps with the diagnosis but can also aid in management by guiding the diagnostic and therapeutic procedure. The pulmonary infections spread by direct or indirect contact with the infected host, droplet transmission, or an airborne spread. In rare cases, some infections can also be transmitted by vectors, namely, insect or animal hosts, and rarely by direct invasion from nearby infected organs. Pulmonary infections may have typical imaging patterns and distribution based on the mode of spread. There are a number of well-described imaging patterns of alveolar infections. The localization and morphological features on imaging may help in the diagnosis of infection and identification of mode of infection and, in certain cases, the microorganism responsible for the infection.

Radiologic evaluation of pulmonary injury following carmustine- and cyclophosphamide-based preparative regimen for autologous peripheral blood stem cell transplantation in children

BACKGROUND

Toxicity of carmustine and cyclophosphamide can cause pulmonary injury after hematopoietic stem cell transplantation.

OBJECTIVE

To evaluate the radiologic findings of pulmonary injuries following carmustine- and cyclophosphamide-based preparative regimens in children.

MATERIALS AND METHODS

From 2010 to 2014, 35 children received carmustine- and cyclophosphamide-based preparative regimens. Fourteen of 35 children presented with symptoms and radiologic abnormalities. Eight of 14 children had no evidence of infection, cardiogenic edema, or other explainable causes. We retrospectively analyzed their chest radiographs and CT scans for ground-glass opacity, consolidation, septal thickening and pleural effusion.

RESULTS

Major chest radiographic findings were bilateral diffuse ground-glass opacity (n=8) and septal thickening (n=7). CT findings were multifocal patchy (n=4) or inhomogeneously diffuse (n=4) ground-glass opacity, multifocal consolidations (n=7) and septal thickening (n=7). All of these lesions at CT were bilateral, but showed lower lobe predominance in 88, 100, and 63%, respectively. There was no central/peripheral or anterior/posterior predilection. Six children had small pleural effusions, which were bilateral in five children.

CONCLUSION

Bilateral ground-glass opacity with or without consolidation, septal thickening and pleural effusion were common radiologic findings in pulmonary injury following carmustine- and cyclophosphamide-based preparative regimens.

The Diagnostic Yield, Safety, and Impact of Flexible Bronchoscopy in Non-HIV Immunocompromised Critically Ill Patients in the Intensive Care Unit

Background

Flexible bronchoscopy (FB) and bronchoalveolar lavage (BAL) have major roles in the evaluation of parenchymal lung diseases in immunocompromised patients. Given the limited evidence, lack of standardized practice, and variable perception of procedural safety, uncertainty still exists on what constitutes the best approach in critically ill patients with immunocompromised state who present with pulmonary infiltrates in the era of prophylactic antimicrobials and the presence of new diagnostic tests.

Objective

To evaluate the diagnostic yield, safety and impact of FB and BAL on management decisions in immunocompromised critically ill patients admitted to the intensive care unit (ICU).

Methods

A prospective, observational study of 106 non-HIV immunocompromised patients admitted to the intensive care unit with pulmonary infiltrates who underwent FB with BAL.

Results

FB and BAL established the diagnosis in 38 (33%) of cases, and had a positive impact on management in 44 (38.3%) of cases. Escalation of ventilator support was not required in 94 (81.7%) of cases, while 18 (15.7%) required invasive and 3 (2.6%) required non-invasive positive pressure ventilation after the procedure. Three patients (2.6%) died within 24 h of bronchoscopy, and 46 patients (40%) died in ICU. Significant hypoxemia developed in 5% of cases.

Conclusion

FB can be safely performed in immunocompromised critically ill patients in the ICU. The yield can be improved when FB is done prior to initiation of empiric antimicrobials, within 24 h of admission to the ICU, and in patients with focal disease.

[Pneumonia in immunosuppressed patients]

CLINICAL/METHODICAL ISSUE

Pulmonary infections are a common complication in immunosuppressed patients with a frequently fatal prognosis despite modern prophylactic therapy. An early and correct diagnosis is important for initiation of the appropriate therapy.

STANDARD RADIOLOGICAL METHODS

Chest radiography is the preferred initial imaging examination but is not accurate enough for the detection of pulmonary infections in immunosuppressed patients.

METHODICAL INNOVATIONS

Pneumonia is caused by a broad spectrum of pathogens in immunocompromised patients. In addition to imaging, the clinical history and epidemiology also play an important role in the diagnostics.

PERFORMANCE

Using epidemiological and anamnestic information, computed tomography (CT) shows a significantly better sensitivity and specificity particularly for the diagnosis of atypical forms of pneumonia. Due to the exact imaging of the different infiltration patterns CT provides an increased sensitivity with respect to the etiological classification of pulmonary infections.

PRACTICAL RECOMMENDATIONS

This article reviews in particular the radiological findings of commonly occurring pulmonary infections in immunosuppressed patients.

Atypical Presentation of Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder characterized by the presence of the Philadelphia chromosome, t(9;22), which is a constitutively active tyrosine kinase that causes excessive proliferation and differentiation of myeloid cells in the bone marrow. Most patients are either asymptomatic or present with fatigue, abdominal fullness, and splenomegaly. This is a case in which a 72-year-old Caucasian male’s initial presentation of CML was new-onset atrial fibrillation, chronic obstructive pulmonary disease (COPD) exacerbation, and pneumonia. The severity of his symptoms of atrial fibrillation and dyspnea complicated his stabilization, which delayed his diagnosis of CML and initiation of tyrosine kinase inhibitor for treatment. Unregulated proliferation of leukemic cells increases blood viscosity and results in aberrations in blood circulation that may result in atypical presenting symptoms in myeloproliferative disease. Thus, it is important to have a high clinical index of suspicion for CML in patients with leukocytosis and concurrent symptomatology that is unusual for leukemia.

Infectious Disease Report: Bordetella pertussis Infection in Patients With Cancer

We illustrate 2 cases of pneumonia associated with Bordetella pertussis infection in 72-year-old and 61-year-old patients with cancer receiving myelosuppressive therapy after hematopoietic stem cell transplantation. Bacterial infections are a significant cause of morbidity and mortality in patients with cancer, and those receiving hematopoietic stem cell transplant, solid organ transplant, or myelosuppressive therapy are at increased risk. The infection was detected and the 2 patients had good outcomes following azithromycin treatment. Pertussis, also known as whooping cough, is a contagious respiratory illness that has become a public health challenge due to decreased immunity of the pertussis vaccine. Therefore, it is critical to recognize pertussis early in the course of the disease.

Respiratory infections in immunocompromised patients: Lung findings using chest computed tomography

Respiratory infections and subsequent complications are one of the leading causes of high mortality in immunocompromised patients. Although chest radiograph and computed tomography are the commonly used diagnostic tools for the early diagnosis of lung manifestations of infections, they lack the specificity for the wide range of chest infections which can occur in immunocompromised patients. Systematic analysis of the imaging findings in correlation with the clinical settings along with comparison with the old images can expedite early and accurate diagnosis for subsequent appropriate management. Computer tomography findings in immunocompromised patients with respiratory infections, with regards to various clinical settings, will be discussed here.

Diagnostic Approach to Life-Threatening Pulmonary Infiltrates

Diagnosis of pulmonary disease is typically based upon consideration of presenting symptoms, physical examination, and pulmonary function testing in combination with classification of radiographic features, to guide diagnostic tests and initiate empiric treatment. When diagnostic efforts and/or empiric treatment fails, thoracic surgeons have traditionally been called upon to perform surgical biopsy of the lung to aid in the diagnosis of indeterminate, life-threatening pulmonary disease. Such biopsy has been requested specifically in the case of diffuse lung disease among patients receiving treatment for solid-organ or hematologic cancers, particularly when symptoms of respiratory failure progress and when noninvasive diagnostic tests and empiric treatments fail to halt progression. In such circumstances, radiologists, pulmonologists, and thoracic surgeons may be consulted and asked to provide tissue specimens that will allow rapid, accurate diagnosis leading to specific treatment. It is imperative that biopsy take place before respiratory failure supervenes [1], and that the specimens provided to clinical laboratories, pathologists, and microbiologists are comprehensive and properly preserved.

Pulmonary Infections: Imaging with CT

Computed tomography (CT) plays a key role in various kinds of pulmonary infections especially in immunocompromised patients, owing to its much higher sensitivity and specificity than the traditionally performed chest X-ray. CT permits the detection of the main infectious pattern and associated findings with high confidence and allows for the precise assessment of all involved structures, to potentially guide a bronchoalveolar lavage or another diagnostic procedure, and to ensure a reliable follow-up. It may be performed at a carefully chosen dose, which may nearly reach that of a chest X-ray in specific situations. The importance of post-processing tools is undeniable in some conditions, in particular for the evaluation of micronodules in the immunocompromised population. The wide spectrum of features of specific organisms according to the immune status, such as in aspergillosis or tuberculosis, must be known, as well as the potential of atypical presentations in case of Pneumocystis jirovecii (PCP) pneumonia when occurring in non-HIV immunocompromised patients. In all cases, underlying disorders must be considered as well as all the differential diagnoses. Overall, CT definitely helps clinicians to diagnose pulmonary infections and to make treatment decisions, especially in vulnerable patients.

Neisseria lactamica Causing a Lung Cavity and Skin Rash in a Renal Transplant Patient: First Report from India

Neisseria lactamica, a commensal, has been very rarely reported to cause diseases in immunocompromised hosts. In medical literature, there is only one report of a cavitatory lung lesion caused by it. The patient was a kidney transplant recipient. Neisseria lactamica was found to be the cause of his pulmonary cavity and a desquamating rash on feet. With the rapidly spreading medical advance, more and more patients are getting organ transplants, so the population of immunocompromised people is on the rise. We expect more sinister and less expected organisms to cause diseases in patients who have organ transplants.

Parainfluenza virus type 3 pneumonia in bone marrow transplant recipients: multiple small nodules in high- resolution lung computed tomography scans provide a radiological clue to diagnosis

We report the findings of high-resolution chest computed tomography of 6 hematopoietic stem cell transplant recipients with parainfluenza virus type 3 pneumonia who were not infected with any other pathogens. All patients had multiple small nodules (diameter, !5 mm) without cavitation ina peribronchial distribution. Changes preceded microbiological diagnosis in 4 of 6 cases.

Cancer survivorship, a unique and growing cohort in medical practice: radiology perspective

The unique medical and psychologic burdens of cancer survivorship have only recently been recognized. This rapidly expanding cohort of patients will be seen increasingly by non-oncology physicians who must consider medical issues related to their cancer or its therapy for any presenting symptoms. Appropriate use of clinical imaging is essential for diagnosing treatment-related complications, recurrent tumor, or emergence of second primaries. This article will review clinical imaging in common medical problems uniquely found in cancer survivors.

CT-guided biopsies in lung infections in patients with haematological malignancies

CT-guided transparietal lung biopsy in imaging makes it possible to find the pathogenic agent in half of all fungal infections and most bacterial infections (sensitivity=55%, specificity=100%). Performance is decreased in consolidations (50% of infections) compared to masses. Complications, pneumothorax, alveolar bleeding and hemoptysis are generally benign and rarely (<5%) require specific treatment. On the other hand, the diagnostic performance increases significantly with the calibre of 18G co-axial systems compared to 20G. The risk is not related to the number of samples or platelet levels.

Radiological spectrum of pulmonary infections in patients post solid organ transplantation

Pneumonia remains an important source of morbidity and mortality in transplant recipients. Since clinical findings are nonspecific and cultures may be time-consuming, imaging plays an important role in establishing the probable etiology of pneumonia. Plain films are used as an initial study. However, they have a limited capacity in differentiating the causative factors. HRCT is used as a problem-solving tool in patients with unclear plain film findings and/or no response to treatment. The main advantage of HRCT is a very detailed depiction of the lung parenchyma. Even though HRCT findings are not always specific, there are several sings that are more common in certain types of pneumonia. The aim of the article is to present radiological findings suggestive of a particular causative microorganism and show how they can narrow the differential diagnosis when coupled with clinical data.

ACR appropriateness criteria(®)acute respiratory illness in immunocompromised patients

The respiratory system is often affected by complications of immunodeficiency, typically manifesting clinically as acute respiratory illness. Ongoing literature reviews regarding the appropriateness of imaging in these patients are critical, as advanced medical therapies such as stem cell transplantation, chemotherapy, and immunosuppressive therapies for autoimmune disease continue to keep high the population of immunosuppressed patients in our health care system today. This ACR Appropriateness Criteria(®) topic describes clinical scenarios of acute respiratory illness in immunocompromised patients with cough, dyspnea, chest pain, and fever; in those with negative, equivocal, or nonspecific findings on chest radiography; in those with diffuse or confluent opacities on chest radiography; and in those in whom noninfectious disease is suspected. The use of chest radiography, chest CT, transthoracic needle biopsy, and nuclear medicine imaging are all discussed in the contexts of these clinical scenarios. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Lung infections: the radiologist's perspective

Imaging plays a key role in lung infections. A CT scan must be carried out when there is a strong clinical suspicion of pneumonia that is accompanied by normal, ambiguous, or nonspecific radiography, a scenario that occurs most commonly in immunocompromised patients. CT allows clinicians to detect associated abnormalities or an underlying condition and it can guide bronchoalveolar lavage or a percutaneous or transbronchial lung biopsy. An organism can vary in how it is expressed depending on the extent to which the patient is immunocompromised. This is seen in tuberculosis in patients with AIDS. The infective agents vary with the type of immune deficiency and some infections can quickly become life-threatening. Clinicians should be aware of the complex radiological spectrum of pulmonary aspergillosis, given that this diagnosis must be considered in specific settings.

Pulmonary complications in the non-HIV immunocompromised patient

The incidence of non-HIV immunocompromised patients is increasing. This is primarily due to improved immunosuppressive regimes for autoimmune diseases and also increases in stem cell transplantation. Pulmonary complications are a major cause of morbidity and mortality in these patients. Imaging is frequently used to assess these complications and to streamline therapies, as microbiological and/or pathological diagnosis can often be difficult, invasive, or protracted. This review provides the reader with a structured approach to interpret the imaging findings and differentiate between different infective and non-infective complications in these patients.

Multiple pulmonary nodules in ectopic adrenocorticotropic hormone syndrome: cause or result?

OBJECTIVE

To report a case of invasive pulmonary aspergillosis mimicking lung cancer with lung to lung metastases in ectopic adrenocorticotropic hormone syndrome (EAS).

CLINICAL PRESENTATION AND INTERVENTION

A 60-year-old man suffering from hypokalemic alkalosis, hypertension and limbs paralysis was referred to our hospital. EAS caused by malignancy of lung was highly suspected due to multiple pulmonary nodules presenting on chest film and positron emission tomography (PET) images. Video-assisted thoracic surgical biopsy tissue was used to confirm invasive aspergillosis instead of malignancy. Finally, the patient died of opportunistic infection.

CONCLUSION

This case showed that although EAS is usually associated with solid tumors, multiple pulmonary nodules secondary to opportunistic infections such as invasive aspergillosis must be kept in mind.

Pseudomonas bronchopulmonary infections in a palliative care setting

Blood stream infections and pneumonia caused by Pseudomonas aeruginosa is associated with high mortality, especially in an immunocompromised host. A large section of the palliative care patient population has varied forms of compromised immunity due to advanced cancer or cancer treatment, organ failures, chronic autoimmune disorders, degenerative conditions, and acquired immunodeficiency syndrome. The lung is one of the most frequently involved organs in a variety of complications in an immunocompromised host and infection is the most common complication. P. aeruginosa is one of the most common pathogens associated with bronchopulmonary infections in an immunocompromised host. Routine radiological tests like chest X-ray may often be unyielding and an early and a prompt initiation of treatment reduces mortality and morbidity risk.

Incipient and subclinical tuberculosis: defining early disease states in the context of host immune response

Latent Mycobacterium tuberculosis infection (LTBI) and active tuberculosis (TB) are 2 ends of a spectrum of states ranging from asymptomatic infection to overt disease. While progressing from LTBI to TB, patients often undergo asymptomatic states with detectable manifestations indicative of disease. Such asymptomatic disease states frequently remain undiagnosed, and their manifestations and duration are mostly dependent on host immune response. Various terms referring to such states are used in the literature, often interchangeably and without explicit definitions. Defining these intermediate states in concrete terms is important for pragmatic reasons, as they might impact upon the diagnostic performance of TB biomarkers and could also present targets for therapeutic interventions. We here propose definitions for 2 commonly used terms, "incipient" and "subclinical" TB, to describe asymptomatic disease states occurring at opposite ends of the host response spectrum. We propose using the term "incipient TB" when referring to early, contained disease in asymptomatic, relatively immunocompetent persons. In contrast, we propose using the term "subclinical TB" to refer to disease in asymptomatic, immunocompromised individuals in whom it is largely associated with loss of effective containment. The rationale for this article is to facilitate the discussion of such early disease states, especially in relation to their impact on TB biomarker discovery and assessment of new diagnostics, and with regard to treatment decisions and ultimately outcome.

Impact of clinical data on chest radiography sensitivity in detecting pulmonary abnormalities in immunocompromised patients with suspected pneumonia

PURPOSE

Chest radiography (CXR) of immunocompromised patients has low sensitivity in the early evaluation of pulmonary abnormalities suspected to be infectious. The purpose of the study was to evaluate whether the knowledge of clinical data improves the diagnostic sensitivity of CXR in the particular setting of immunocompromised patients after hematopoietic stem cell transplantation (HSCT).

MATERIALS AND METHODS

Sixty-four CXRs of immunocompromised patients with clinically suspected pneumonia were retrospectively and independently evaluated by two radiologists to assess the presence of radiological signs of pneumonia, before (first reading) and after (second reading) the knowledge of clinical data. A chest computed tomography (CT) performed within 3 days was assumed as the standard of reference. For each reading, sensitivity of both radiologists was calculated.

RESULTS

Readers showed a sensitivity of 39% and 58.5% for the first reading, and 43.9% and 41.5% for the second reading, respectively. For both readers, these values were not significantly different from those obtained at first reading (McNemar's test, p>0.05). Interobserver agreement at second reading was fair (Cohen test, k=0.33).

CONCLUSIONS

The sensitivity of CXR is too low to consider it a stand-alone technique for the evaluation of immunocompromised patients after HSCT with suspected pneumonia, even if the radiologist knows detailed clinical data. For these patients, an early chest CT evaluation is therefore recommended.

Pulmonary infections in HIV-positive children

Infection of the lungs and airways by viral, bacterial, fungal and protozoal agents, often producing atypical radiographic features, is common in children with human immunodeficiency virus (HIV) infection. Conventional chest radiography and chest CT remain the most useful imaging modalities for evaluation of the immunocompromised patient presenting with a suspected pulmonary infection. In this review the radiological features of acute lung infections in this population are discussed.

Candidiasis in pediatric patients with cancer interned in a university hospital

Fungi are common causes of infection in immunocompromised patients. Candida species are frequently involved in these cases. In order to investigate candidiasis in pediatric patients with cancer, clinical samples were collected from one hundred and twenty two patients interned in the Oswaldo Cruz University Hospital in Recife, Brazil. Yeasts were isolated from thirty-four clinical samples. The species isolated were: Candida albicans (fourteen isolates), C. parapsilosis (nine isolates), C. guilliermondii (two isolates) and C. tropicalis (two isolates). We found that candidemia was most frequent in patients with malignant hematology and that C. parapsilosis infections caused the highest mortality.

Comparison of CT features of Aspergillus and bacterial pneumonia in severely neutropenic patients

PURPOSE

To establish whether a relationship exists between computed tomography features of lung opacities in severely neutropenic patients and their Aspergillus or bacterial etiology.

METHODS

Computed tomography scans of 124 patients with lung opacities larger than 5 mm occurring during severe (neutrophils <500/mm) and prolonged (>7 d) neutropenia-induced by bone marrow transplantation and/or high-dose chemotherapy for hematologic malignancies-were reviewed. Invasive pulmonary aspergillosis or bacterial pneumonia were assessed by means of bronchoalveolar lavage, bronchial washing, trans-bronchial biopsy or (for bacteria only) blood cultures. Pulmonary opacities were classified as nodules or as consolidations. The presence of a perinodular ground-glass halo, the similarity of consolidations to a pulmonary infarction and the presence of cavitation (crescent-shaped or not) were recorded.

RESULTS

Invasive pulmonary aspergillosis was diagnosed in 68 patients; bacterial pneumonia in 56. Nodules (85) were more common than consolidations (39); their distribution among the patients with aspergillosis (52 nodules and 16 consolidations) and those with bacterial pneumonia (33 nodules and 23 consolidations) was even. Out of the 19 nodules surrounded by a halo 17 were due to aspergillosis. Nine consolidations (3 due to aspergillosis) were infarctionlike shaped. Cavitation appeared during 22/68 aspergillosis and 31/56 bacterial pneumonias; an air-crescent in 6 patients with aspergillosis and in 24 with bacterial pneumonia.

CONCLUSIONS

Although rare enough, the perinodular halo is highly specific for invasive aspergillosis. The nodular pattern of lung opacities, their similarity to a pulmonary infarction, the occurrence of cavitation and the air-crescent are not related to aspergillosis.

Acute lung infections in normal and immunocompromised hosts

Pulmonary infections are among the most common causes of morbidity and mortality worldwide, and contribute substantially to annual medical expenditures in the United States. Despite the availability of antimicrobial agents, pneumonia constitutes the sixth most common cause of death and the number one cause of death from infection. Pneumonia can be particularly life-threatening in the elderly, in individuals who have pre-existing heart and lung conditions, in patients who have suppressed or weakened immunity, and in pregnant women. This article discusses some of the important causes of acute lung infections in normal and immunocompromised hosts. Because there often is considerable overlap, infections are categorized by the host immune status that is most likely to be associated with a particular pathogen.

Pulmonary infections after bone marrow transplantation: high-resolution CT findings in 111 patients

OBJECTIVE

The purpose of this study was to review the high-resolution CT findings in patients with pulmonary infection after bone marrow transplantation and to determine distinguishing features among the various types of infection.

MATERIALS AND METHODS

This study included 111 consecutive bone marrow transplant recipients who had documented pulmonary infection, high-resolution CT of the chest performed within 24 hr of the beginning of symptoms, and proven diagnosis within 1 week of the onset of symptoms. Two radiologists analyzed the CT scans and reached final decisions regarding the findings by consensus. Statistical analysis was performed using the Fisher's exact test and multivariate analysis; a p value of less than 0.05 was considered statistically significant.

RESULTS

The pulmonary infections were due to viruses (n = 57), bacteria (n = 26), fungi (n = 21), and protozoa (n = 1). Six patients had more than one organism responsible for the infection. Nodules that were 1 cm or more in diameter were seen in 13 (62%) of 21 patients with fungal pneumonia, five (19%) of 26 patients with bacterial pneumonia (p = 0.0059), three (10%) of 30 with respiratory syncytial virus (RSV) pneumonia (p = 0.0001), and three (14%) of 22 with cytomegalovirus pneumonia (p = 0.0016). The halo sign was present in 10 of 21 patients with fungal pneumonia, two of 26 with bacterial pneumonia (p = 0.0026), three of 30 with RSV pneumonia (p = 0.0036), and one of 22 with cytomegalovirus pneumonia (p = 0.0015). There was no statistically significant difference in the prevalence of the other CT patterns including small nodules, ground-glass attenuation, and air-space consolidation among viral, bacterial, and fungal infections (all p > 0.05).

CONCLUSION

The presence of large nodules and visualization of the halo sign are most suggestive of fungal infection. Other high-resolution CT patterns are not helpful in distinguishing among the various types of infection seen in bone marrow transplant recipients.

High-resolution computed tomography (HRCT) of lung infections in non-AIDS immunocompromised patients

Non-AIDS immunocompromised patients are susceptible to infections by a wide range of organisms. In the past several decades, advances in the treatment of cancer, organ transplantation, and immunosuppressive therapy have resulted in large numbers of patients who develop abnormalities in their immune system. Moreover, mildly impaired host immunity as it occurs in chronic debilitating illness, diabetes mellitus, malnutrition, alcoholism, advanced age, prolonged corticosteroid administration, and chronic obstructive lung disease have also been regarded as predisposing factors of pulmonary infections. Imaging plays a crucial role in the detection and management of patients with pulmonary infectious diseases. When pulmonary infection is suspected, knowledge of the varied radiographic manifestations will narrow the differential diagnosis, helping to direct additional diagnostic measures and serving as an ideal tool for follow-up examinations. Combination of pattern recognition with knowledge of the clinical setting is the best approach to pulmonary infection occurring in the immunocompromised patients.