Thoracic paracoccidioidomycosis: radiographic and CT findings

Pulmonary Infection

Pneumonia is a significant cause of morbidity and mortality in the community and hospital settings. Bacterial, viral, mycobacterial, and fungal pathogens are all potential causative agents of pulmonary infection. Chest radiographs and computed tomography are frequently utilized in the assessment of pneumonia. Learning the imaging patterns of different potential organisms allows the radiologist to formulate an appropriate differential diagnosis. An organism-based approach is used to discuss the imaging findings of different etiologies of pulmonary infection.

Insights into Magnetic Resonance Imaging Findings in Central Nervous System Paracoccidioidomycosis: A Comprehensive Review

Paracoccidioidomycosis (PCM) is a infection caused by the thermodimorphic fungus Paracoccidioides spp. (P. lutzii and, mainly, P. brasiliensis). This infection predominantly affects rural male workers aged between 30 and 50 years old who deal with soil on daily activities. Clinically, the disease is classified as acute/subacute phase, which evolves rapidly, secondary to dissemination of the fungus through to the phagocytic-mononuclear system, leading to fever, weight loss, and anorexia, associated with hepatosplenomegaly and lymphadenopathy, which can be complicated with suppuration and fistulization; and chronic phase, which corresponds to 74% to 95% of symptomatic cases, with a common pulmonary involvement. Central nervous system involvement is almost always a characteristic of the chronic form. Inhalation is the most common route of primary infection, usually affecting the lungs, forming the primary complex. From the primary complex, hematogenic dissemination can occur to any organ, including the brain and spinal cord. Although PCM of the central nervous system diagnosis is usually based on histopathological analysis and the imaging features are not specific for PCM, computed tomography and magnetic resonance imaging can demonstrate evidences of granuloma, abscess, meningitis, or a combination of these lesions, contributing to a preoperative diagnosis, especially when considered in conjunction with epidemiology. In this article, we review the pathophysiology, clinical manifestations and imaging aspects of neuro-PCM.

Chest Imaging in Systemic Endemic Mycoses

Endemic fungal infections are responsible for high rates of morbidity and mortality in certain regions of the world. The diagnosis and management remain a challenge, and the reason could be explained by the lack of disease awareness, variability of symptoms, and insidious and often overlooked clinical presentation. Imaging findings are nonspecific and frequently misinterpreted as other more common infectious or malignant diseases. Patient demographics and clinical and travel history are important clues that may lead to a proper diagnosis. The purpose of this paper is to review the presentation and differential diagnosis of endemic mycoses based on the most common chest imaging findings.

Disseminated paracoccidioidomycosis in a liver transplant patient

Paracoccidioidomycosis is an endemic systemic mycosis caused by Paracoccidioides brasiliensis complex and P. lutzii. It is a rare disease in non-HIV-induced immunosuppressed individuals. In organ transplant recipients, it is more frequently associated with immunosuppression after kidney transplantation. In a liver transplant patient, only one case has been published in the literature to date. The present report comprises the case of a 47-year-old female patient with disseminated skin lesions associated with signs and symptoms of systemic involvement of paracoccidioidomycosis that manifested one year after liver transplantation and under an immunosuppression regimen with tacrolimus and mycophenolate mofetil.

Thoracic Endemic Fungi in the United States: Importance of Patient Location

The digitization of radiographic studies along with high-speed transmission of images has formed the basis of teleradiology, which has become an integral component in the workflow of a contemporary radiology practice. It is with this advent and growing utilization of teleradiology that the significance of the source location of images has gained importance. Specifically, the importance of where the patient resides and what endemic fungi occur in that location cannot be underestimated. In the United States, histoplasmosis, coccidioidomycosis, blastomycosis, and cryptococcosis are caused by endemic fungi occurring in the Ohio and Mississippi river valleys, the Southwest, the Upper Midwest, and the Pacific Northwest, respectively. All of these organisms enter the body through the respiratory system and have the potential to cause significant morbidity and mortality. Patients infected with these fungi are often asymptomatic but may present with acute flulike symptoms such as fever, cough, or dyspnea. Patients may also present with vague chronic symptoms including cough, fever, malaise, and weight loss. Thoracic manifestations at radiography and CT include consolidation, nodules, cavities, lymphadenopathy, and pleural disease. PET may show fluorine 18-fluorodeoxyglucose uptake with active acute or chronic infections, and it is difficult to distinguish infections from malignancy. Imaging findings may be nonspecific and can be confused with other disease processes, including malignancy. The patient demographics, clinical history, and location are clues that may lead to a proper diagnosis of endemic fungal disease. The radiologist should be cognizant of the patient location to provide a correct and timely radiologic diagnosis that helps guide the clinician to initiate appropriate therapy. ^©RSNA, 2021.

Updates in Paracoccidioides Biology and Genetic Advances in Fungus Manipulation

The dimorphic fungi of the Paracoccidioides genus are the causative agents of paracoccidioidomycosis (PCM). This disease is endemic in Latin America and primarily affects workers in rural areas. PCM is considered a neglected disease, despite being a disabling disease that has a notable impact on the public health system. Paracoccidioides spp. are thermally dimorphic fungi that present infective mycelia at 25 °C and differentiate into pathogenic yeast forms at 37 °C. This transition involves a series of morphological, structural, and metabolic changes which are essential for their survival inside hosts. As a pathogen, the fungus is subjected to several varieties of stress conditions, including the host immune response, which involves the production of reactive nitrogen and oxygen species, thermal stress due to temperature changes during the transition, pH alterations within phagolysosomes, and hypoxia inside granulomas. Over the years, studies focusing on understanding the establishment and development of PCM have been conducted with several limitations due to the low effectiveness of strategies for the genetic manipulation of Paracoccidioides spp. This review describes the most relevant biological features of Paracoccidioides spp., including aspects of the phylogeny, ecology, stress response, infection, and evasion mechanisms of the fungus. We also discuss the genetic aspects and difficulties of fungal manipulation, and, finally, describe the advances in molecular biology that may be employed in molecular research on this fungus in the future.

Endemic mycoses: epidemiology and diagnostic strategies

INTRODUCTION

The global frequency of endemic mycoses has considerably increased, mainly due to environmental changes, population growth in endemic areas, and the increase in HIV-related immunosuppressed status. Among the most frequent endemic mycoses are coccidioidomycosis in semi-desert climates, and paracoccidioidomycosis, and histoplasmosis in tropical climates. The inoculum can enter the host through the airway or directly through the skin. Lymphatic and hematogenous spread may involve the skin.

AREAS COVERED

In this article, we provide up-to-date epidemiological and diagnostic data on major (histoplasmosis, paracoccidioidomycosis, coccidioidomycosis, blastomycosis) and minor (talaromycosis, adiaspiromycosis, emergomycosis) endemic mycoses.

EXPERT OPINION

Endemic mycoses include diseases with a localized endemic area, and a few of them converge. These mycoses all have in common the airway involvement and can cause pulmonary symptoms following initial asymptomatic infection. Among the risk groups to acquire these mycoses are travelers from endemic areas, archeologists, speleologists, and immigrants. Promising and useful diagnostic tools have been developed in endemic mycoses; however, most of them are not standardized or available in low-income countries.

Infectious Lung Disease

Infectious diseases are one of the main causes of morbidity and mortality worldwide. With new pathogens continuously emerging, known infectious diseases reemerging, increasing microbial resistance to antimicrobial agents, global environmental change, ease of world travel, and an increasing immunosuppressed population, recognition of infectious diseases plays an ever-important role in surgical pathology. This becomes particularly significant in cases where infectious disease is not suspected clinically and the initial diagnostic workup fails to include samples for culture. As such, it is not uncommon that a lung biopsy becomes the only material available in the diagnostic process of an infectious disease. Once the infectious nature of the pathological process is established, careful search for the causative agent is advised. This can often be achieved by examination of the hematoxylin and eosin-stained sections alone as many organisms or their cytopathic effects are visible on routine staining. However, ancillary studies such as histochemical stains, immunohistochemistry, in situ hybridization, or molecular techniques may be needed to identify the organism in tissue sections or for further characterization, such as speciation.

Endemic pulmonary fungal diseases in immunocompetent patients: an emphasis on thoracic imaging

INTRODUCTION

Systemic endemic mycoses are prevalent in specific geographical areas of the world and are responsible for high rates of morbidity and mortality in these populations, and in immigrants and travelers returning from endemic regions. The most common fungal infections that can affect the lungs of immunocompetent patients include histoplasmosis, coccidioidomycosis, paracoccidioidomycosis, blastomycosis, sporotrichosis, aspergillosis, and cryptococcosis. Diagnosis and management of these diseases remain challenging, especially in non-endemic areas due to the lack of experience. Therefore, recognition of the various radiologic manifestations of pulmonary fungal infections associated with patients' clinical and epidemiologic history is imperative for narrowing the differential diagnosis. Areas covered: This review discusses the clinical and radiological findings of the main endemic fungal diseases affecting the lungs in immunocompetent patients. Specific topics discussed are their etiology, epidemiology, pathogenesis, clinical manifestations, methods of diagnosis, pathology and main imaging findings, especially in computed tomography. Expert commentary: Imaging plays an important role in the diagnosis and management of pulmonary fungal infection and may reveal useful signs. Although definitive diagnosis cannot be made based on imaging features alone, the use of a combination of epidemiologic, clinical and imaging findings may permit the formulation of an adequate differential diagnosis.

Chronic Cavitary Infections Other than Tuberculosis: Clinical Aspects

Lung cavitation may be due to infectious or noninfectious pathologic processes. The latter category includes nonmalignant conditions, such as granulomatosis with polyangiitis, and malignant conditions, such as squamous cell carcinoma of the lung. Infectious etiologies that produce lung cavitation usually cause chronic illness, although some, particularly pyogenic bacteria, may produce acute cavitary disease. Tuberculosis is the most common cause of chronic pulmonary infection with cavitation. The goal of this review was to highlight a selection of the better-known infectious agents, other than tuberculosis, that can cause chronic lung disease with cavitation. Emphasis is placed on the following organisms: nontuberculous mycobacteria, Histoplasma, Blastomyces, Coccidioides, Paracoccidioides, Aspergillus, Burkholderia pseudomallei, Paragonimus westermani, and Rhodococcus equi. These organisms generally produce clinical features and radiologic findings that overlap or mimic those of tuberculosis. In a companion article, we have further emphasized aspects of the same conditions that are more pertinent to radiologists.

Radiology of Chronic Cavitary Infections

Chronic cavitary lung disease is an uncommon manifestation of pulmonary infection, and is a pattern which worldwide is most commonly caused by reactivation tuberculosis. Other organisms, however, can cause similar radiologic patterns. Endemic fungi have long been recognized as potential causes of this pattern in North and South America, but the frequency with which these diseases present with chronic cavities in North America is relatively small. Nontuberculous mycobacteria and chronic aspergillus infections are recognized with increasing frequency as causes of this pattern. Melioidosis, a bacterial infection that can also cause chronic lung cavities, was previously understood to be relevant primarily in Southeast Asia, but is now understood to have a wider geographic range. While cultures, serologies, and other laboratory methods are key to identifying the infectious causes of chronic lung cavities, radiologic evaluation can contribute to the diagnosis. Differentiating the radiologic patterns of these diseases from reactivation tuberculosis depends on subtle differences in imaging findings and, in some cases, appreciation of underlying lung disease.

Tomographic assessment of thoracic fungal diseases: a pattern and signs approach

Pulmonary fungal infections, which can be opportunistic or endemic, lead to considerable morbidity and mortality. Such infections have multiple clinical presentations and imaging patterns, overlapping with those of various other diseases, complicating the diagnostic approach. Given the immensity of Brazil, knowledge of the epidemiological context of pulmonary fungal infections in the various regions of the country is paramount when considering their differential diagnoses. In addition, defining the patient immunological status will facilitate the identification of opportunistic infections, such as those occurring in patients with AIDS or febrile neutropenia. Histoplasmosis, coccidioidomycosis, and paracoccidioidomycosis usually affect immunocompetent patients, whereas aspergillosis, candidiasis, cryptococcosis, and pneumocystosis tend to affect those who are immunocompromised. Ground-glass opacities, nodules, consolidations, a miliary pattern, cavitary lesions, the halo sign/reversed halo sign, and bronchiectasis are typical imaging patterns in the lungs and will be described individually, as will less common lesions such as pleural effusion, mediastinal lesions, pleural effusion, and chest wall involvement. Interpreting such tomographic patterns/signs on computed tomography scans together with the patient immunological status and epidemiological context can facilitate the differential diagnosis by narrowing the options.

Imaging paracoccidioidomycosis: A pictorial review from head to toe

Paracoccidioidomycosis is an infectious disease characterized primarily by pulmonary involvement and potential dissemination to other organs, mainly mucosa and skin; however, it can affect any organ in the body. Although difficult to diagnose purely based on imaging, imaging is important for diagnosis, follow-up, and assessment of disease-related complications. We provide a comprehensive review of the most notable imaging findings of paracoccidioidomycosis.

Diffuse cystic lung diseases: differential diagnosis

Diffuse cystic lung diseases are characterized by cysts in more than one lung lobe, the cysts originating from various mechanisms, including the expansion of the distal airspaces due to airway obstruction, necrosis of the airway walls, and parenchymal destruction. The progression of these diseases is variable. One essential tool in the evaluation of these diseases is HRCT, because it improves the characterization of pulmonary cysts (including their distribution, size, and length) and the evaluation of the regularity of the cyst wall, as well as the identification of associated pulmonary and extrapulmonary lesions. When combined with clinical and laboratory findings, HRCT is often sufficient for the etiological definition of diffuse lung cysts, avoiding the need for lung biopsy. The differential diagnoses of diffuse cystic lung diseases are myriad, including neoplastic, inflammatory, and infectious etiologies. Pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, lymphocytic interstitial pneumonia, and follicular bronchiolitis are the most common diseases that produce this CT pattern. However, new diseases have been included as potential determinants of this pattern.

Performance of magnetic resonance imaging in pulmonary fungal disease compared to high-resolution computed tomography

To evaluate the performance of magnetic resonance imaging (MRI) compared to computed tomography (CT) in patients diagnosed with pulmonary mycosis. We prospectively included 21 patients diagnosed with pulmonary mycosis between January 2013 and October 2014. Inclusion criteria were presence of respiratory symptoms, histopathological diagnosis of mycosis and absence of mycosis treatment. Reviewers identified one predominant imaging pattern per patient: nodular, reticular or airspace pattern. Afterwards, all CT findings were analysed separately per lobe and compared to MRI. Nodular pattern was the most common found (CT: 76.20%; MRI: 80.96%), followed by airspace pattern (CT and MRI: 9.52%) and reticular (CT: 9.52%; MRI: 4.76%). Compared to CT, MRI performance varied according to radiological finding and pulmonary region. For nodules, MRI presented high sensitivity (100% [95% CI: 93.52-100]) and specificity (100% [95% CI: 92.00-100]). For bronchiectasis and septal thickening, there were poorer positive predictive values (33.33% [95% CI: 1.77-87.47]; and 83.33% [95% CI: 50.88-97.06] respectively). As specificity and negative predictive value had superior results than sensitivity and positive predictive value, rather than for diagnosis of this condition, MRI might be more considered for the follow-up of patients with pulmonary mycosis, an alternative to multiple radiation exposures with CT follow-up.

A 54-Year-Old Man With Lingual Granuloma and Multiple Pulmonary Excavated Nodules

A 54-year-old French man was admitted for evaluation of a chronic nodular lesion of the tongue and mandibular lymphadenopathy. He reported active tobacco and cannabis smoking as well as excessive alcohol use. He also reported frequent use of cocaine for several months and a past addiction to IV heroin. He had traveled abroad as a journalist and lived for several months in Columbia and Venezuela 12 years ago. His medical history included chronic hepatitis C infection successfully treated with interferon and ribavirin 6 years ago and high BP.

Paracoccidioides-host Interaction: An Overview on Recent Advances in the Paracoccidioidomycosis

Paracoccidioides brasiliensis and P. lutzii are etiologic agents of paracoccidioidomycosis (PCM), an important endemic mycosis in Latin America. During its evolution, these fungi have developed characteristics and mechanisms that allow their growth in adverse conditions within their host through which they efficiently cause disease. This process is multi-factorial and involves host-pathogen interactions (adaptation, adhesion, and invasion), as well as fungal virulence and host immune response. In this review, we demonstrated the glycoproteins and polysaccharides network, which composes the cell wall of Paracoccidioides spp. These are important for the change of conidia or mycelial (26°C) to parasitic yeast (37°C). The morphological switch, a mechanism for the pathogen to adapt and thrive inside the host, is obligatory for the establishment of the infection and seems to be related to pathogenicity. For these fungi, one of the most important steps during the interaction with the host is the adhesion. Cell surface proteins called adhesins, responsible for the first contact with host cells, contribute to host colonization and invasion by mediating this process. These fungi also present the capacity to form biofilm and through which they may evade the host's immune system. During infection, Paracoccidioides spp. can interact with different host cell types and has the ability to modulate the host's adaptive and/or innate immune response. In addition, it participates and interferes in the coagulation system and phenomena like cytoskeletal rearrangement and apoptosis. In recent years, Paracoccidioides spp. have had their endemic areas expanding in correlation with the expansion of agriculture. In response, several studies were developed to understand the infection using in vitro and in vivo systems, including alternative non-mammal models. Moreover, new advances were made in treating these infections using both well-established and new antifungal agents. These included natural and/or derivate synthetic substances as well as vaccines, peptides, and anti-adhesins sera. Because of all the advances in the PCM study, this review has the objective to summarize all of the recent discoveries on Paracoccidioides-host interaction, with particular emphasis on fungi surface proteins (molecules that play a fundamental role in the adhesion and/or dissemination of the fungi to host-cells), as well as advances in the treatment of PCM with new and well-established antifungal agents and approaches.

CT morphological features of the reversed halo sign in pulmonary paracoccidioidomycosis

OBJECTIVE

The purpose of this study was to identify morphological characteristics of the reversed halo sign (RHS) on chest CT in patients with pulmonary paracoccidioidomycosis (PCM) that may aid the diagnosis of this fungal disease.

METHODS

We retrospectively reviewed chest CT images from 23 patients with proven pulmonary PCM who demonstrated the RHS. Two chest radiologists analysed the morphological characteristics of the lesions and reached decisions by consensus.

RESULTS

We identified 64 RHSs on CT images from the 23 patients. Multiple lesions were observed in all cases, with middle and lower lung zone predominance occurring in 17 patients (73.9% of cases). 34 (53.1%) RHSs were round and 30 (46.9%) were oval. Outer borders of the RHSs were smooth in 32 (50%) lesions, nodular in 16 (25%) lesions and irregular/spiculated in 16 (25%) lesions. Ground-glass opacity was observed inside 63 (98.4%) lesions.

CONCLUSION

Our data suggest that morphological characteristics of the RHS on chest CT, such as the presence of multiple lesions, middle and lower lung zone predominance and a spiculated RHS ring, as well as the association with other parenchymal patterns, should lead radiologists to include PCM in the differential diagnosis of PCM in endemic areas.

ADVANCES IN KNOWLEDGE

This is the largest series of patients with RHS due to PCM and is also the first study to report RHS lesions with spiculated or irregular walls. The study adds information regarding morphological characteristics of the RHS that may raise suspicion of PCM on chest CT, particularly in endemic areas of the disease.

Computed tomography findings of paracoccidiodomycosis in musculoskeletal system

Objective

To evaluate musculoskeletal involvement in paracoccidioidomycosis at computed tomography.

Materials and Methods

Development of a retrospective study based on a review of radiologic and pathologic reports in the institution database. Patients with histopathologically confirmed musculoskeletal paracoccidioidomycosis and submitted to computed tomography were included in the present study. The imaging findings were consensually described by two radiologists. In order to avoid bias in the analysis, one patient with uncountable bone lesions was excluded from the study.

Results

A total of seven patients were included in the present study. A total of 18 bone lesions were counted. The study group consisted of 7 patients. A total number of 18 bone lesions were counted. Osteoarticular lesions were the first manifestation of the disease in four patients (57.14%). Bone lesions were multiple in 42.85% of patients. Appendicular and axial skeleton were affected in 85.71% and 42.85% of cases, respectively. Bone involvement was characterized by well-demarcated osteolytic lesions. Marginal osteosclerosis was identified in 72.22% of the lesions, while lamellar periosteal reaction and soft tissue component were present in 5.55% of them. One patient showed multiple small lesions with bone sequestra.

Conclusion

Paracoccidioidomycosis can be included in the differential diagnosis of either single or multiple osteolytic lesions in young patients even in the absence of a previous diagnosis of pulmonary or visceral paracoccidioidomycosis

Lung cysts in chronic paracoccidioidomycosis

On HRCT scans, lung cysts are characterized by rounded areas of low attenuation in the lung parenchyma and a well-defined interface with the normal adjacent lung. The most common cystic lung diseases are lymphangioleiomyomatosis, Langerhans cell histiocytosis, and lymphocytic interstitial pneumonia. In a retrospective analysis of the HRCT findings in 50 patients diagnosed with chronic paracoccidioidomycosis, we found lung cysts in 5 cases (10%), indicating that patients with paracoccidioidomycosis can present with lung cysts on HRCT scans. Therefore, paracoccidioidomycosis should be included in the differential diagnosis of cystic lung diseases.

Surgery for other pulmonary fungal infections, Actinomyces, and Nocardia

Surgical participation in the management of fungal infections has changed since the advent of effective antimicrobials. Even so, a surgeon may be called on for a variety of reasons, depending on the specific fungal infection and the evolution of thoracic disease. Specific fungal infections are enumerated. Each organism, its clinical picture, and method of diagnosis are briefly described and the medical and surgical management of thoracic disease are discussed.

The lung in paracoccidioidomycosis: new insights into old problems

OBJECTIVES

Chronic paracoccidioidomycosis can diffusely affect the lungs. Even after antifungal therapy, patients may present with residual respiratory abnormalities due to fungus-induced lung fibrosis.

METHODS

A cross-sectional analysis of 50 consecutive inactive, chronic paracoccidioidomycosis patients was performed using high resolution computed tomography, pulmonary function tests, ergospirometry, the six-minute walk test and health-related quality of life questionnaires.

RESULTS

Radiological abnormalities were present in 98% of cases, the most frequent of which were architectural distortion (90%), reticulate and septal thickening (88%), centrilobular and paraseptal emphysema (84%) and parenchymal bands (74%). Patients typically presented with a mild obstructive disorder and a mild reduction in diffusion capacity with preserved exercise capacity, including VO2max and six-minute walking distance. Patient evaluation with the Saint-George Respiratory Questionnaire showed low impairment in the health-related quality of life, and the Medical Research Council questionnaire indicated a low dyspnea index. There were, however, patients with significant oxygen desaturation upon exercise that was associated with respiratory distress compared with the non-desaturated patients. The initial counterimmunoelectrophoresis of these patients was higher and lung emphysema was more prominent; however, there were no differences in the interstitial fibrotic tomographic abnormalities, tobacco exposure, functional responses, exercise capacity or quality of life.

CONCLUSIONS

Inactive, chronic paracoccidioidomycosis patients show persistent and disseminated radiological abnormalities by high resolution computed tomography, short impairments in pulmonary function and low impacts on aerobic capacity and quality of life. However, there was a subset of individuals whose functional impairment was more severe. These patients present with higher initial serology and more severe emphysema, stressing the importance of adequate treatment associated with tobacco exposure cessation.

Pleural effusion an unusual feature of paracoccidioidomycosis: report of two new cases with a systematic review of the literature

Paracoccidioidomycosis (PCM) is an endemic disease restricted geographically to Latin America. Brazil accounts for about 80 % of the reported cases, and lungs are most frequently affected. A suggestive radiograph of PCM may only be seen late in the course of the disease. At the beginning, it mimics tuberculosis. On the other hand, pleural effusion on rare occasions has been reported in PCM. For this reason, we report two cases with such uncommon manifestation. Our first patient presented pleural effusion probably caused by PCM (a previously unreported cause of lung mass accompanied by effusion); the second with proved pleural effusion due to PCM. A systematic review of the literature was done.

Important aspects of oral paracoccidioidomycosis--a literature review

Paracoccidioidomycosis is a deep mycosis endemic to Latin America, with considerable morbidity and mortality. It is caused by the dimorphic fungus Paracoccidioides brasiliensis, which affects, among other organs in the human body, the oral cavity. Fungus virulence and immunocompetence of the host determine the establishment of infection or active disease, whose severity and clinical behaviour depend mostly on the cellular immune response of the host. Often, oral lesions constitute the first sign and site of confirmation of diagnosis, which in most cases is delayed. The success of the treatment depends on early and correct diagnosis, as well as on the patient's adherence to the drug therapy.