Pulmonary tuberculosis associated with the reversed halo sign on high-resolution CT

Reversed halo sign as a radiological feature of tuberculosis - Report of two cases

Reversed halo sign (RHS) is a radiological feature described as a focal, rounded area of ground-glass opacity surrounded by a ring of consolidation. In this report we describe two unique radiological cases demonstrating diffuse bilateral infiltrates with multiple RHSs in chest CT scans. Both patients were ultimately diagnosed as having tuberculosis (TB) and had been exposed to silica in the past. This report presents for the first time an association between silica exposure and RHS on CT scans among TB patients. It highlights the importance of having a high index of suspicion for TB in similar scenarios.

Ultrasonic humidifier lung with a reversed halo sign: A case report

The reversed halo sign was initially reported as a representative computed tomography scan finding of cryptogenic organizing pneumonia. Since then, however, it has been reported in various diseases and is now considered a nonspecific finding. However, there are no cases of humidifier lung with the reversed halo sign. An 82-year-old Japanese male patient presented with moving difficulties 48 days after starting darolutamide treatment for prostate cancer. He was admitted to the hospital due to acute pneumonia, which presented as bilateral extensive nonsegmental ground-glass opacities in the peripheral regions and extensive areas of ground-glass opacity with a circumferential halo of consolidation, with the reversed halo sign on computed tomography scan. After darolutamide discontinuation with the concomitant administration of antibiotics, the patient's pneumonia improved, and he was discharged from the hospital. However, within a few days, he was again admitted to the hospital due to pneumonia. He was found to have been using an ultrasonic humidifier at home and was then diagnosed with humidifier lung based on the bronchoscopy and provocative testing findings. Hence, ultrasonic humidifier lung should be considered as a differential diagnosis in patients presenting with the reversed halo sign, and a detailed medical history must be taken.

Diffuse reversed halo sign in an immunocompetent patient

The reversed halo sign (RHS) is a specific radiological image observed mostly on computed tomography (CT) scans as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation. It is common to many entities of respiratory diseases and can be found in both infectious, noninfectious inflammatory pathologies and some malignant tumors, including invasive pulmonary fungal infection, tuberculosis (TB), community-acquired pneumonia, granulomatosis, sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation and radiofrequency. We report the case of an immunocompetent 54-year-old North African male patient, initially hospitalized for chronic cough associated with dysphonia and general symptoms such as weight loss, fever, and night sweats. Radiological exploration surprisingly confirmed the presence of RHS, tuberculosis was confirmed by a postbronchoscopy positive sputum Xpert MTB/RIF essay tuberculosis after we started antibacillary treatment, and the evolution was spectacular with regression of the lesions. The objective of this report is to increase knowledge about RHS and its pathological correlation with TB. Since it is not specific to any disorder, it is important to explore its finding in a clinical and epidemiological manner, especially in endemic countries where the prevalence of tuberculosis is still high.

Active pulmonary tuberculosis: something old, something new, something borrowed, something blue

Tuberculosis remains a major global health issue affecting all countries and age groups. Radiology plays a crucial role in the diagnosis and management of pulmonary tuberculosis (PTB). This review aims to improve understanding and diagnostic value of imaging in PTB. We present the old, well-established findings ranging from primary TB to the common appearances of post-primary TB, including dissemination with tree-in-bud nodularity, haematogenous dissemination with miliary nodules and lymphatic dissemination. We discuss new concepts in active PTB with special focus on imaging findings in immunocompromised individuals. We illustrate PTB appearances borrowed from other diseases in which the signs were initially described: the reversed halo sign, the galaxy sign and the cluster sign. There are several radiological signs that have been shown to correlate with positive or negative sputum smears, and radiologists should be aware of these signs as they play an important role in guiding the need for isolation and empirical anti-tuberculous therapy.

Illustration of a number of atypical computed tomography manifestations of active pulmonary tuberculosis

Tuberculosis is a serious public health challenge facing mankind and one of the top ten causes of death. Diagnostic imaging plays an important role, particularly for the diagnosis and treatment planning of tuberculosis patients with negative microbiology results. This article illustrates a number of atypical computed tomography (CT) appearances of pulmonary tuberculosis (PTB), including (I) clustered micronodules (CMNs) sign; (II) reversed halo sign (RHS); (III) tuberculous pneumatocele; (IV) hematogenously disseminated PTB with predominantly diffuse ground glass opacity manifestation; (V) hematogenously disseminated PTB with randomly distributed non-miliary nodules; (VI) PTB changes occur on the background of emphysema or honeycomb changes of interstitial pneumonia; and (VII) PTB manifesting as organizing pneumonia. While the overall incidence of PTB is decreasing globally, the incidence of atypical manifestations of tuberculosis is increasing. A good understanding of the atypical CT imaging changes of active PTB shall help the diagnosis and differential diagnosis of PTB in clinical practice.

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.

Reversed Halo Sign: Presents in Different Pulmonary Diseases

OBJECTIVE

To observe the incidence of reversed halo sign in different pulmonary diseases and the pathological correspondence of reversed halo sign.

METHODS

Retrospectively studied the high resolution computer tomography scans of all the patients who were admitted in our department with abnormal pulmonary imaging, from 1st of January 2011 to 31st of December 2013, and all the cases with reversed halo sign on the high resolution computer tomography were collected. Clinical data such as pathological findings and confirmed diagnosis of the patients with reversed halo sign on the high resolution computer tomography scan were collected and summarized.

RESULTS

Of 1546 abnormal High resolution computer tomography scans 108 had a reverse halo sign present, including 108 cases were observed with reversed halo sign in the high resolution computer tomography, including 40 cases of pulmonary tuberculosis, 43 cases of cryptogenic organizing pneumonia, 16 cases of lung cancer, 7 cases of sarcoidosis, and 1 case of pulmonary cryptococcosis, 1 case of granulomatosis with polyangiitis. Reversed halo sign had a higher incidence in granulomatous diseases (16.28%) compared with non-granulomatous diseases (9.97%).

CONCLUSIONS

Reversed halo sign is relatively non specific; it can be observed in different lung diseases, and different phases of diseases; reversed halo sign is more commonly found in granulomatous diseases compared with non-granulomatous diseases, and is most commonly observed in pulmonary tuberculosis among the granulomatous diseases, and in cryptogenic organizing pneumonia among the non-granulomatous diseases.

Clinicoradiologic evidence of pulmonary lymphatic spread in adult patients with tuberculosis

OBJECTIVE

The purpose of this study is to evaluate the prevalence and clinicoradiologic characteristics of pulmonary tuberculosis with lymphatic involvement.

MATERIALS AND METHODS

A total of 126 adults with active tuberculosis who underwent CT were enrolled. A retrospective investigation of CT images focused on the presence of perilymphatic micronodules, as well as other CT features of active tuberculosis. We selected two groups of patients with micronodules according to distribution (perilymphatic vs centrilobular). We compared clinical and CT findings between the two groups.

RESULTS

Fifteen patients were excluded because of coexisting pulmonary disease. Among 111 patients, the prevalence of perilymphatic micronodules, galaxy or cluster signs, and interlobular septal thickening was 64 (58%), 18 (16%), and 30 (27%), respectively. Of 106 patients with micronodules, 37 and 40 were classified into the perilymphatic and centrilobular groups, respectively. Compared with the centrilobular group, the perilymphatic group had statistically significantly lower frequencies of positive acid-fast bacilli smears (32% vs 70%), consolidation (70% vs 98%), and cavitation (30% vs 60%). However, frequencies of interlobular septal thickening (41% vs 18%), galaxy or cluster signs (30% vs 0%), and pleural effusion (43% vs 20%) were statistically significantly higher in the perilymphatic group.

CONCLUSION

CT findings representing pulmonary perilymphatic involvement are relatively common in adults with tuberculosis. These findings may represent lymphatic spread of tuberculosis and provide an explanation for the unusual CT features of pulmonary tuberculosis mimicking sarcoidosis and the low detection of Mycobacterium tuberculosis in patients with micronodules.

Unusual presentation of chronic eosinophilic pneumonia with "reversed halo sign": a case report

The reversed halo sign (RHS) may sometimes be seen in patients with cryptogenic organizing pneumonia (COP), but is rarely associated with other diseases. Herein, we present a case of a 21-year-old woman with chronic eosinophilic pneumonia, with high resolution computed tomography (HRCT) finding of RHS. This is an unusual and rare presentation of chronic eosinophilic pneumonia.

High-resolution CT findings of pulmonary infections after orthotopic liver transplantation in 453 patients

OBJECTIVES

The objective of this study was to review the high-resolution CT (HRCT) findings in patients with pulmonary infection after orthotopic liver transplantation (OLT) and to determine distinguishing findings among the various types of infection.

METHODS

This study included 453 consecutive liver transplant recipients with pulmonary infection, on whom HRCT of the chest was performed within 24 h of the beginning of symptoms and for whom proven diagnosis had taken place within 1 week of the onset of symptoms. Two radiologists analysed the CT images; final decisions regarding the findings were reached by consensus.

RESULTS

Bacterial and viral pneumonia made up the bulk of infections (63.4% and 29.4%, respectively), followed by fungal infiltrates (24.5%). Large nodules were most common in patients with fungal pneumonia, having been seen in 38 (54%) of the 70 patients with fungal pneumonia, 22 (10%) of 220 with bacterial pneumonia (p=0.0059) and 6 (8%) of 78 with viral pneumonia (p=0.0011). The halo sign was also more frequent in patients with fungal pneumonia, having been seen in 38 (54%) of the 70 patients with fungal pneumonia, 17 (8%) of 220 with bacterial pneumonia (p=0.0026) and 7 (9%) of 78 with viral pneumonia (p=0.0015). There was no statistically significant difference in the prevalence of the other HRCT patterns including air-space consolidation, ground-glass attenuation and small nodules among bacterial, viral and fungal infections (all p>0.05).

CONCLUSION

The presence of large nodules with the halo sign is most suggestive of fungal infection after OLT. Other HRCT patterns are not helpful in distinguishing among the various types of infection seen in liver transplant recipients.

Thoracic paracoccidioidomycosis: radiographic and CT findings

Paracoccidioidomycosis (PCM) is the most common systemic mycosis in Latin America. Although most cases occur in developing countries, recent immigration patterns and an increase in travel have led to a growing number of PCM cases in the United States and Europe. PCM is caused by the dimorphic fungus Paracoccidioides brasiliensis, and the chronic form may progress to severe pulmonary involvement. Several radiologic patterns have been described for pulmonary PCM, including linear and reticular opacities, variable-sized nodules, patchy ill-defined opacities, airspace consolidation, and cavitary lesions. Fibrosis and paracicatricial emphysema are common associated findings. Chest computed tomography (CT) is the method of choice for evaluating pulmonary PCM, with the most common CT findings being ground-glass attenuation, consolidation, small or large nodules, masses, cavitations, interlobular septal thickening, emphysema, and fibrotic lesions. PCM is also an important cause of the "reversed halo" sign at high-resolution CT and should be considered in the differential diagnosis. Awareness of the multiple radiologic manifestations of PCM as well as its epidemiologic and clinical characteristics may permit early diagnosis and initiation of specific treatment, thereby reducing associated morbidity and mortality.

Reversed halo sign on computed tomography: state-of-the-art review

The reversed halo sign (RHS) is a chest computed tomography (CT) pattern defined as a focal round area of ground-glass attenuation surrounded by a crescent or ring of consolidation. The RHS was first described as being relatively specific for cryptogenic organizing pneumonia but was later observed in several other infectious and noninfectious diseases. Although the presence of the RHS on CT may help narrow the range of diseases considered in differential diagnoses, final diagnoses should be based on correlation with the clinical scenario and the presence of additional disease-specific CT findings. However, frequently a biopsy may be needed to establish the diagnosis. Organizing pneumonia is the most frequent cause of the RHS. This is a distinct clinical and pathologic entity that can be cryptogenic or secondary to other known causes. Morphologic aspects of the halo, particularly the presence of small nodules in the wall or inside the lesion, usually indicate an active granulomatous disease (tuberculosis or sarcoidosis) rather than organizing pneumonia. Immunocompromised patients presenting with the RHS on CT examination should be considered to have an infection until further analyses prove otherwise. Pulmonary zygomycosis and invasive pulmonary aspergillosis are typically seen in patients with severe immunosuppression, most commonly secondary to hematological malignancies. Other causes of the RHS include noninvasive fungal infections such as paracoccidioidomycosis, histoplasmosis, and Pneumocystis jiroveci pneumonia. Furthermore, Wegener's granulomatosis, radiofrequency ablation, and lymphomatoid granulomatosis may also lead to this finding. Based on a search of the PubMed and Scopus databases, we review the different diseases that can manifest with the RHS on CT.

The reversed halo sign: update and differential diagnosis

The reversed halo sign is characterised by a central ground-glass opacity surrounded by denser air-space consolidation in the shape of a crescent or a ring. It was first described on high-resolution CT as being specific for cryptogenic organising pneumonia. Since then, the reversed halo sign has been reported in association with a wide range of pulmonary diseases, including invasive pulmonary fungal infections, paracoccidioidomycosis, pneumocystis pneumonia, tuberculosis, community-acquired pneumonia, lymphomatoid granulomatosis, Wegener granulomatosis, lipoid pneumonia and sarcoidosis. It is also seen in pulmonary neoplasms and infarction, and following radiation therapy and radiofrequency ablation of pulmonary malignancies. In this article, we present the spectrum of neoplastic and non-neoplastic diseases that may show the reversed halo sign and offer helpful clues for assisting in the differential diagnosis. By integrating the patient's clinical history with the presence of the reversed halo sign and other accompanying radiological findings, the radiologist should be able to narrow the differential diagnosis substantially, and may be able to provide a presumptive final diagnosis, which may obviate the need for biopsy in selected cases, especially in the immunosuppressed population.

H1N1 pneumonia: our experience in 50 patients with a severe clinical course of novel swine-origin influenza A (H1N1) virus (S-OIV)

PURPOSE

The authors reviewed chest radiographs (CXR) and thin-section computed tomography (CT) findings of pulmonary complications in a selected population of 50 consecutive patients with severe novel swine-origin influenza A (H1N1) virus (S-OIV) pneumonia who were seen at the Subintensive Respiratory Unit (UTSIR) and at the Intensive Care Unit (ICU) at Monaldi Hospital, Naples, Italy.

MATERIALS AND METHODS

CXR and CT findings of 50 patients who fulfilled the World Health Organisation (WHO) criteria for S-OIV infection were reviewed by four radiologists. The final study group of 50 patients was divided into two subgroups on the basis of clinical course: group 1 consisted of 42 patients requiring noninvasive mechanical ventilation and admitted to the UTSIR; group 2 consisted of eight patients who required ICU admission and extracorporeal membrane oxygenation or advanced mechanical ventilation from October 2009 to December 2009. All patients underwent CXR and thin-section multidetector CT (MDCT) scan; the initial and follow-up radiographs and CT scans were evaluated for the presentation and follow-up pattern (consolidation, ground-glass opacities, nodules, reticulation), distribution and extent of abnormality.

RESULTS

All patients had radiological signs of pulmonary involvement. Ground-glass opacity and consolidation, which was mainly peripheral, was the most frequent finding. In three patients, we report for the first time in viral pneumonia the reversed halo sign. Lesion extent was related to aggressiveness of the illness. More often, both lungs were involved (82%). Thoracic comorbidity was present in 18% of patients; 22% of patients was obese, and in this group, the clinical course was more aggressive than in the others with the same lesion extent at imaging. Furthermore, superinfection led to worsening of the clinical conditions.

CONCLUSIONS

The most common CXR and CT findings in patients with S-OIV infection were unilateral or bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. On MDCT, ground-glass opacities and areas of consolidation had a predominant peribronchovascular and subpleural distribution, resembling organising pneumonia; they progressed to bilateral extensive airspace disease in severely ill patients.

Reversed halo sign in active pulmonary tuberculosis: criteria for differentiation from cryptogenic organizing pneumonia

OBJECTIVE

The purpose of this study was to compare the morphologic characteristics of the "reversed halo" sign caused by tuberculosis with those caused by cryptogenic organizing pneumonia (COP) and to determine whether high-resolution CT (HRCT) can differentiate between these two conditions.

MATERIALS AND METHODS

We retrospectively reviewed the HRCT scans of patients with the reversed halo sign caused by active tuberculosis and HRCT scans of patients with the reversed halo sign caused by COP. The study included 12 patients with active pulmonary tuberculosis (10 women and two men) and 10 patients with biopsy-proven COP (five women and five men). Tuberculosis was diagnosed by culture of sputum, bronchoalveolar lavage, or biopsy specimen. All patients underwent HRCT, and the images were reviewed by two chest radiologists who reached decisions by consensus.

RESULTS

HRCT scans of all patients with active tuberculosis showed reversed halos with nodular walls; in most cases (10/12), we also observed nodules inside the halos. None of the HRCT scans of the COP cases reviewed had halos with nodular walls or nodules inside them. We also observed parenchymal abnormalities, such as consolidation, ground-glass, and linear opacities, associated with the reversed halo sign. Neither the number of reversed halo sign lesions nor the associated parenchymal lesions discriminated between tuberculosis and COP. Nevertheless, the association of the reversed halo sign with nodular walls or nodules inside the halo was seen only in tuberculosis patients.

CONCLUSION

Although COP is considered the most frequent cause of the reversed halo sign, the presence of nodular walls or nodules inside the reversed halo strongly favors a diagnosis of active pulmonary tuberculosis rather than COP.

Cunninghamella bertholletiae pneumonia showing a reversed halo sign on chest computed tomography scan following cord blood transplantation

This is the first reported case of a patient who developed fungal pneumonia caused by Cunninghamella bertholletiae (= C. elegans) following cord blood transplantation and who showed a reversed halo sign on a chest computed tomography scan (CT). In addition, the pathological findings related to the reversed halo sign are described in detail for the first time. The patient died due to respiratory failure and at autopsy, a consolidation corresponding to the reversed halo sign noted on CT was found histologically to be composed of a central infarct with some retained air spaces surrounded by a peripheral ring-like hemorrhagic band. Pulmonary vasculatures were occluded by thrombi containing numerous Zygomycetes hyphae within the central infarct and less frequently along the surrounding hemorrhagic band. A reversed halo sign may be an early marker to initiate preemptive therapy against Zygomycetes including C. bertholletiae.

Reversed halo sign: high-resolution CT scan findings in 79 patients

BACKGROUND

The purpose of this study was to evaluate the high-resolution CT (HRCT) scan findings of patients with the reversed halo sign (RHS) and to identify distinguishing features among the various causes.

METHODS

Two chest radiologists reviewed the HRCT scans of 79 patients with RHS and determined the CT scan findings by consensus. We studied the morphologic characteristics, number of lesions, and presence of features associated with RHS.

RESULTS

Forty-one patients presented with infectious diseases (paracoccidioidomycosis, TB, zygomycosis, invasive pulmonary aspergillosis, Pneumocystis jiroveci pneumonia, histoplasmosis, cryptococcosis), and 38 presented with noninfectious diseases (cryptogenic organizing pneumonia, pulmonary embolism, sarcoidosis, edema, lepidic predominant adenocarcinoma [formerly bronchiolo-alveolar carcinoma], granulomatosis with polyangiitis [Wegener]). The RHS walls were smooth in 58 patients (73.4%) and nodular in 21 patients (26.6%). Lesions were multiple in 40 patients (50.6%) and single in 39 patients (49.4%).

CONCLUSION

The presence of nodular walls or nodules inside the halo of the RHS is highly suggestive of granulomatous diseases.

The reversed halo sign on high-resolution CT in infectious and noninfectious pulmonary diseases

OBJECTIVE

The purpose of this article is to describe diseases that may present with the reversed halo sign on high-resolution CT. We emphasize the tomographic features most frequently associated with this sign and correlate them with histologic findings.

CONCLUSION

A wide spectrum of infectious and noninfectious diseases may present with the reversed halo sign on chest CT. The nonspecific nature of this sign should not cloud an otherwise fairly straightforward diagnosis, especially when associated background findings are typical. Although a rigorous analysis of associated CT findings may help with the differential diagnosis, histologic assessment is often needed for a definitive determination of the cause.

The diagnostic value of halo and reversed halo signs for invasive mold infections in compromised hosts

The halo sign is a CT finding of ground-glass opacity surrounding a pulmonary nodule or mass. The reversed halo sign is a focal rounded area of ground-glass opacity surrounded by a crescent or complete ring of consolidation. In severely immunocompromised patients, these signs are highly suggestive of early infection by an angioinvasive fungus. The halo sign and reversed halo sign are most commonly associated with invasive pulmonary aspergillosis and pulmonary mucormycosis, respectively. Many other infections and noninfectious conditions, such as neoplastic and inflammatory processes, may also manifest with pulmonary nodules associated with either sign. Although nonspecific, both signs can be useful for preemptive initiation of antifungal therapy in the appropriate clinical setting. This review aims to evaluate the diagnostic value of the halo sign and reversed halo sign in immunocompromised hosts and describes the wide spectrum of diseases associated with them.

Reversed halo sign in pneumocystis pneumonia: a case report

Background

The reversed halo sign may sometimes be seen in patients with cryptogenic organizing pneumonia, but is rarely associated with other diseases.

Case presentation

We present a case study of a 32-year-old male patient with acquired immunodeficiency syndrome, who had previously been treated with chemotherapy for non-Hodgkin's lymphoma. A chest X-ray showed bilateral patchy infiltrates. High-resolution computed tomography revealed the reversed halo sign in both upper lobes. The patient was diagnosed with pneumocystis pneumonia, which was successfully treated with sulfamethoxazole trimethoprim; the reversed halo sign disappeared, leaving cystic lesions. Cases such as this one are rare, but show that the reversed halo sign may occur in patients who do not have cryptogenic organizing pneumonia.

Conclusion

Physicians can avoid making an incorrect diagnosis and prescribing the wrong treatment by carefully evaluating all clinical criteria rather than assuming that the reversed halo sign only occurs with cryptogenic organizing pneumonia.