El “cúmulo sarcoideo”. Un nuevo signo en tomografía computarizada de tórax de alta resolución

Pulmonary tuberculosis presenting with cluster sign and galaxy sign

In a routine medical check-up, a healthy man in his 20s was found to have an upper left lung abnormality. Subsequent chest CT revealed the cluster sign (CS) and galaxy sign (GS). Although tests such as sputum analysis and interferon-gamma assays reduced the likelihood of tuberculosis, these abnormalities remained unchanged. A lung biopsy indicated non-caseating granuloma unrelated to tuberculosis. Initially suspected of sarcoidosis, the patient later developed fever and malaise. Follow-up CT showed CS progressing to a cavitatory shadow and GS intensification. The detection of Mycobacterium tuberculosis (M. tuberculosis) in a subsequent sputum analysis prompted treatment with antitubercular drugs, leading to symptom relief.CS and GS are usually associated with sarcoidosis but can also occur in tuberculosis, connected to slower pathogen growth and lower isolation rates. Furthermore, pulmonary tuberculosis may ultimately be present even when biopsies show non-caseating granulomas that are not typical of M. tuberculosis and sputum culture results are negative for M. tuberculosis Tuberculosis should not be ruled out lightly, and patients should be carefully followed-up.

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.

Dilemma of diagnosing thoracic sarcoidosis in tuberculosis endemic regions: An imaging-based approach. Part 1

Sarcoidosis is a multi-systemic disorder of unknown etiology, although commonly believed to be immune-mediated. Histologically, it is characterized by noncaseating granuloma which contrasts against the caseating granuloma seen in tuberculosis (TB), an infectious disease that closely mimics sarcoidosis, both clinically as well as radiologically. In TB-endemic regions, the overlapping clinico-radiological manifestations create significant diagnostic dilemma, especially since the management options are markedly different in the two entities. Part 1 of this review aims to summarize the clinical, laboratory, and imaging features of sarcoidosis, encompassing both typical and atypical manifestations, in an attempt to distinguish between the two disease entities.

Unilateral Nonconfluent Cluster of Micronodules: Atypical Radiologic Appearance of Pulmonary Tuberculosis in an Immunocompetent Patient

Active pulmonary tuberculosis involving the lung parenchyma is typically seen on CT as consolidation, centrilobular nodules with tree-in-bud branching, cavitating lesions, and miliary nodules. However, some atypical CT patterns of granulomatous disease including tuberculosis have been recently described, namely, clusters of nodules without confluence or with confluence. We present a case of a patient who was found to have nonconfluent clusters of micronodules in the right lung with negative sputum culture for tuberculosis. There were also incidental findings of the partial duplex system of the left kidney with mild-to-moderate hydronephrosis in the lower moiety with proximal hydroureter. The urine culture was then positive for mycobacterium tuberculosis; hence, he was commenced on antituberculous medications. A repeated CT scan revealed significant improvement of the aforementioned clusters of micronodules and left hydronephrosis. In the present case, we would like to highlight the atypical appearances of pulmonary tuberculosis in the form of nonconfluent micronodules on HRCT despite negative sputum workup, with the concurrent active genitourinary tuberculosis.

Nodular reverse halo sign in active pulmonary tuberculosis: A rare CT feature?

PURPOSE

The purpose of this study was to investigate the prevalence of the nodular reverse halo sign (NRHS) in chest computed tomography (CT) in patients with active pulmonary tuberculosis.

MATERIALS AND METHODS

From March 2018 to March 2019, 29 consecutive patients with a culture-confirmed active pulmonary tuberculosis and who underwent chest CT examination during hospital-admission were retrospectively included in the study. There were 24 men and 5 women with a mean age of 40.9±16.7 (SD) years (range: 18-80years). Chest CT examinations of included patients were evaluated for the presence of NRHS and other tuberculosis-related CT signs.

RESULTS

CT revealed the NRHS in 5 patients (5/29; 17%). The other CT signs of tuberculosis included consolidations in 18 patients (18/29; 62%), tree-in-bud pattern in 14 patients (14/29; 48%), cavitation in 12 patients (12/29; 41%), sparse nodules in 10 patients (10/29; 34%), and pleural effusion in 8 patients (8/29; 28%).

CONCLUSION

CT shows NRHS in 17% of patients with active pulmonary tuberculosis, indicating that the sign is not as rare as previously thought in patients with this condition.

Sarcoidosis: A Diagnosis of Exclusion

OBJECTIVE. This article will review the typical and atypical imaging features of sarcoidosis, identify entities that may be mistaken for sarcoidosis, and discuss patterns and clinical scenarios that suggest an alternative diagnosis. CONCLUSION. Radiologists must be familiar with the characteristic findings in sarcoidosis and be attentive to situations that suggest alternative diagnoses. The radiologist plays a major role in prompt diagnosis and one that may help reduce patient morbidity and mortality.

Multiple huge "cluster" and "galaxy" signs on chest radiography in a patient with pulmonary tuberculosis

A 62-year-old healthy man presented to our hospital due to a persistent fever of up to 38°C for one week. Thoracic computed tomography showed right pleural effusion with multiple large nodules up to 7 cm in diameter composed of numerous discrete small nodules like fireworks, the so-called "cluster" signs. Some of the large nodules had a hyper-dense portion centrally surrounded by partially discrete small nodules, not as densely assembled, suggestive of the "galaxy" sign. The repeated acid-fast sputum smears and both bronchial washings were all negative for Mycobacterium tuberculosis, but the acid-fast culture of sputum taken soon after the first bronchoscopy, and pleural fluid, turned out to be positive for M. tuberculosis at six weeks after admission. The present case clearly demonstrates that the "galaxy" and "cluster" signs are red herring signs of the low rates of isolating M. tuberculosis, which should be differentiated from pulmonary sarcoidosis.

Multi-drug-resistant tuberculosis with galaxy and cluster signs on high-resolution computed tomography

The galaxy sign and cluster sign were first reported in pulmonary sarcoidosis. From those reports, these two signs became known as one of the characteristic computed tomography (CT) findings of sarcoidosis. We report a patient with pulmonary tuberculosis who had these two signs. A 44-year-old man was referred to our hospital for general fatigue, cough, and low-grade fever lasting about two months. Thoracic CT showed a large parenchymal nodule arising from coalescent small nodules (galaxy sign) and clusters composed of numerous small nodules (cluster sign) in the bilateral lungs. Three specimens of sputum acid-fast smear were negative. However, we performed a bronchoscopy, and Mycobacterium tuberculosis was proven to be positive by the acid-fast culture test of the obtained bronchoalveolar lavage fluid. Moreover, drug sensitivity testing revealed this to be a case of multi-drug-resistant tuberculosis. Patients with these signs must be examined carefully to differentiate tuberculosis from pulmonary sarcoidosis.

Approach to Pulmonary Hypertension: From CT to Clinical Diagnosis

Pulmonary hypertension (PH) is a condition characterized by increased pressure in the pulmonary circulation. It may be idiopathic or arise in the setting of other clinical conditions. Patients with PH tend to present with nonspecific cardiovascular or respiratory symptoms. The clinical classification of PH was recently revised at the World Health Organization symposium in Nice, France, in 2013. That consensus statement provided an updated classification based on the shared hemodynamic characteristics and management of the different categories of PH. Some features seen at computed tomography (CT) can suggest a subtype or probable cause of PH that may facilitate placing the patient in the correct category. These features include findings in the pulmonary arteries (peripheral calcification, peripheral dilatation, eccentric filling defects, intra-arterial soft tissue), lung parenchyma (centrilobular nodules, mosaic attenuation, interlobular septal thickening, bronchiectasis, subpleural peripheral opacities, ground-glass opacities, diffuse nodules), heart (congenital lesions, left heart disease, valvular disease), and mediastinum (hypertrophied bronchial arteries). An approach based on identification of these CT features in patients with PH will allow the radiologist to play an important role in diagnosis and help guide the clinician in management of PH. ^©RSNA, 2018.

Serum ACE Level in Sarcoidosis Patients with Typical and Atypical HRCT Manifestation

BACKGROUND

Sarcoidosis is an inflammatory disease that affects multiple organs. Before widespread use of computed tomography (CT), the severity of sarcoidosis was assessed based on chest X-ray abnormalities. HRCT can distinguish between active inflammatory changes and irreversible fibrosis. In this study, we analyzed different ACE levels in 148 patients diagnosed with sarcoidosis.

MATERIAL/METHODS

We categorized these patients based on their HRCT results into four groups: 1) patients diagnosed with chronic disease; 2) patients diagnosed with non-chronic disease; 3) patients who exhibited typical HRCT changes; and 4) patients who exhibited atypical HRCT changes. Afterward the mean ACE level of each group was calculated and compared.

RESULT

The HRCT scans of chronic sarcoidosis patients tended to show more atypical sarcoidosis patterns. Moreover, there was a reverse correlation between chronicity and ACE level (P-value <0.05).

CONCLUSIONS

HRCT is another modality which would be useful when the diagnosis of sarcoidosis is not definite.

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.

[Thoracic sarcoidosis]

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. It mainly affects the thoracic lymph nodes and the lungs. The staging of sarcoidosis, which classifies patients according to their probability of spontaneous remission, is based on the plain chest film findings. Plain chest films are not as sensitive as high resolution computed tomography (HRCT) at detecting involvement of the lymph nodes, lungs, or bronchi. The high resolution CT findings can be typical, practically pathognomic, or atypical. High resolution CT provides information about the activity of the disease and detects incipient signs of fibrosis and other complications. To reach the diagnosis, it is necessary to correlate the clinical and radiological findings (and often the histological findings). Cardiac involvement can cause sudden death. The diagnosis of cardiac involvement is difficult; it is based on various imaging tests, like magnetic resonance imaging, which is more specific, and positron emission tomography. Diagnostic confirmation by endomyocardial biopsy is obtained in few patients.

Pulmonary sarcoidosis: typical and atypical manifestations at high-resolution CT with pathologic correlation

Sarcoidosis is a multisystem disorder that is characterized by noncaseous epithelioid cell granulomas, which may affect almost any organ. Thoracic involvement is common and accounts for most of the morbidity and mortality associated with the disease. Thoracic radiologic abnormalities are seen at some stage in approximately 90% of patients with sarcoidosis, and an estimated 20% develop chronic lung disease leading to pulmonary fibrosis. Although chest radiography is often the first diagnostic imaging study in patients with pulmonary involvement, computed tomography (CT) is more sensitive for the detection of adenopathy and subtle parenchymal disease. Pulmonary sarcoidosis may manifest with various radiologic patterns: Bilateral hilar lymph node enlargement is the most common finding, followed by interstitial lung disease. At high-resolution CT, the most typical findings of pulmonary involvement are micronodules with a perilymphatic distribution, fibrotic changes, and bilateral perihilar opacities. Atypical manifestations, such as masslike or alveolar opacities, honeycomb-like cysts, miliary opacities, mosaic attenuation, tracheobronchial involvement, and pleural disease, and complications such as aspergillomas, also may be seen. To achieve a timely diagnosis and help reduce associated morbidity and mortality, it is essential to recognize both the typical and the atypical radiologic manifestations of the disease, take note of features that may be suggestive of diseases other than sarcoidosis, and correlate imaging features with pathologic findings to help narrow the differential diagnosis.

Atypical distribution of small nodules on high resolution CT studies: patterns and differentials

Accurate diagnosis of lung disease with high resolution CT is challenging and relies on a pattern-based approach coupled with knowledge of the distribution of the abnormalities in the lung parenchyma. Some findings and distributions of small nodules are specific for certain diseases, but atypical patterns have been described, especially for granulomatous diseases such as sarcoidosis and tuberculosis. Unusual HRCT aspects that involve the coalescence of small nodules have been termed the "sarcoid galaxy sign" and the "sarcoid cluster sign". Other imaging findings such as the "reversed halo sign" and the "fairy ring sign" can also be composed of small nodules. The aim of this review was to describe and illustrate a range of conditions that manifest with atypical distribution of small nodules on HRCT. We discuss the various aspects, associated findings, and differential diagnosis particularly in sarcoidosis and tuberculosis.