CASE 13946 Published on 04.10.2016

Atypical manifestation of pulmonary sarcoidosis simulating metastatic disease

Section

Chest imaging

Case Type

Clinical Cases

Authors

Fahad Mewazy Al-Hamidi, Mark Owen

Withybush General Hospital,
Hywel Dda Health Board, Radiology;
email: Fahad.Mewazy@wales.nhs.uk
Patient

20 years, male

Categories
Area of Interest Lung ; Imaging Technique Conventional radiography, CT
Clinical History
A 20-year-old gentleman complaining of cough and fever for many weeks. No weight loss.
Imaging Findings
Chest radiography revealed bilateral lung nodules and hilar lymphadenopathy. Subsequent CT scan was arranged to rule out malignancy. CT images demonstrated marked bilateral hilar and mediastinal lymphadenopathy, multiple bilateral large nodules and ground glass opacities distributed mainly along the peribronchovascular bundles. No evidence of cavitation, pleural disease or fibrosis. The images showed sarcoid galaxy sign which represented conglomerates of small nodules forming larger nodules and surrounded by tiny satellite nodules.

Bronchoscopic biopsy was performed and revealed non-caseating granulomas. Special stains for fungi and acid-fast bacilli were negative. No evidence of tumour cells. Morphologically the overall appearances would be in keeping with the clinical diagnosis of sarcoid.
Discussion
Sarcoidosis is an immune-mediated multiorgan disorder of unknown aetiology involving mainly the lung and lymphatic organs. 50% of patients are asymptomatic. The most common clinical symptoms of sarcoidosis are fatigability and respiratory symptoms [1, 4, 14].

The most common imaging feature is bilateral symmetrical hilar and paratracheal lymphadenopathy. Mediastinal lymphadenopathy with no hilar nodes is rare. Lymph node calcification suggests chronic disease and is present in up to 50% of cases [2-4, 7, 9].
Other common imaging findings include multiple small nodules along the peribronchovascular bundles, interstitial lung thickening. Fibrosis occurs in 15-20%. Sarcoidosis has a strong predilection for the upper lung parts [11].

Atypical imaging features are present in up to 30% and are relatively more common in patients older than 50 years. Features include unilateral or asymmetric lymphadenopathy, necrosis, cavitation, large nodules, ground glass opacities, bronchial wall nodular thickening, pleural disease, honeycombing, miliary shadowing, mosaic attenuation and aspergillomas. However, atypical features are usually associated with the presence of typical imaging findings such as bilateral hilar lymphadenopathy or perilymphatic nodules. On CT, sarcoid galaxy sign is useful in the diagnosis of pulmonary sarcoidosis. This sign describes coalescence of small nodules to form larger nodules, which are surrounded by tiny satellite nodules [8]. It is a non-specific sign and can be seen in pulmonary tuberculosis, lung cancer and progressive massive fibrosis. However, the presence of extensive hilar and mediastinal lymphadenopathies especially when there is calcification, is more suggestive of sarcoidosis [3, 5, 7, 9-12].

Chest X-ray is useful as initial investigation for the diagnosis, staging, and follow-up of sarcoidosis [1-2, 6]. HRCT is more sensitive than X-ray in the detection of lymphadenopathy and lung parenchymal disease [6, 10]. Radionuclide imaging such as gallium-67 and (18)F-fluorodeoxyglucose are useful in detecting extrathoracic involvement, active disease and assessing treatment response [1]. MRI is useful for the diagnosis of cardiac and neurosarcoidosis [6]. The diagnosis is made after clinical radiological evaluation, histologic evidence of non-caseating granulomas and exclusion of other conditions that can have a similar appearance [2, 13-14].

Treatment of sarcoidosis is based on symptoms and functional or imaging evidence of disease progression. Spontaneous resolution is seen in 50%. In symptomatic patients, corticosteroids is the first-line drug followed by methotrexate. TNFα-antagonists are used in refractory sarcoidosis [15-16].

The prognosis of sarcoidosis depends on the organ involved. The disease outcome ranges from a self-limited subclinical process to chronic debilitation and death, with the major complications being fibrosis, mycetoma formation, and corpulmonale [1, 14]. Others can be secondary to cardiac or neural disease.
Differential Diagnosis List
Sarcoidosis proven by biopsy.
Lymphoma
Metastases
Tuberclosis
Final Diagnosis
Sarcoidosis proven by biopsy.
Case information
URL: https://www.eurorad.org/case/13946
DOI: 10.1594/EURORAD/CASE.13946
ISSN: 1563-4086
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