End-stage pulmonary fibrosis in sarcoidosis

Clinical History

A 38-year-old man was admitted to our hospital because of progressive dyspnoea, non-productive cough, fatigue and non-quantified weight loss for the last year. He denied any recent travel or occupational exposure. The lag time between onset of symptoms and medical visit was explained by a history of unemployment and homelessness.

Imaging Findings

Posteroanterior chest radiograph demonstrated bilateral dense fibrosis causing elevation of both hila and deviation of the trachea to the right indicating a greater degree of volume loss on the right. In the mid zones there is widespread nodularity with relative sparing of the bases. Bilateral lymph nodes were also evident (Figure 1).
The Computed Tomography (CT) of the thorax confirmed bilateral architectural distortion and a fibrotic pattern of disease, with multiple micronodules mainly in a peribronchovascular distribution in the upper lobes. Volume loss and coalescent mass-like peribronchovacular opacities were depicted with central traction bronchiectasis. There was mediastinal shift and upper-lobe bronchi were displaced posteriorly. No honeycombing was seen (Figure 2).
Additionally non-enhanced CT showed extensive bilateral eggshell-like calcifications of hilar and mediastinal lymph nodes (Figure 3).
A high suspicion of sarcoidosis was raised and confirmed by bronchoalveolar lavage and transbronchial biopsy of one of the lymph nodes.

Discussion

Sarcoidosis is a systemic disorder of unknown aetiology that is characterized by the presence of noncaseating granulomas, in which lung and/or thoracic lymph nodes are involved in 90% of cases. It typically affects young to middle-aged adults and there is a slight female predominance [1, 2].

Presentation as an incidental radiographic finding is common and symptoms are nonspecific, including fatigue, weight loss, low-grade fever, skin lesions, musculoskeletal or ocular symptoms. The clinical course varies widely and it is commonly staged according to its appearance on the chest radiograph. The staging system ranges from stage 0 (normal) to stage IV (lung fibrosis), with varying degrees of lymph nodes and parenchymal abnormalities in between [1].

Lymph node enlargement is the most common finding and is usually seen as bilateral and symmetric in hilar, right paratracheal and tracheobronchial regions [3]. Calcification is depicted in up to 50% of cases and may have an amorphous, punctuate or eggshell-like appearance. This latter finding is also common in patients with silicosis and coal-worker’s pneumoconiosis warranting their inclusion in the differential diagnosis [4].
Often showing a middle and upper lung predominance, CT reveals sharply defined, small nodules usually in a bilateral distribution, with about 15% showing significant asymmetry. As sarcoid granulomas in the lung are typically distributed along the lymphatic vessels (perilymphatic distribution) they are characteristically found along bronchovascular margins, subpleurally and interlobular septa. The nodules range in size from just 1mm to over 5mm but conglomeration into irregular opacities or masses is not uncommon [1-3].

The presence of lung fibrosis (stage IV) at the time of presentation on a radiograph occurs in 5% of patients and is correlated with a poor prognosis. Such fibrosis has fairly characteristic findings in CT, such as linear opacities radiating from the hilum mainly to the upper and middle regions associated with volume loss, traction bronchiectasis, superior retraction of the hilum and fissural displacement. This fibrosis is commonly linked with conglomerate parahilar masslike lesions that resemble those seen in progressive massive fibrosis of pneumoconiosis [5].

Corticosteroids remain the corner stone in therapy but for those with end-stage fibrosis lung transplantation remains the only effective option.

The role of the radiologist is to recognize the common patterns of sarcoidosis on HRCT in order to suggest the correct diagnosis in the appropriate clinical setting and eventually obviate the need for biopsy.

Differential Diagnosis List

Final Diagnosis

End-stage pulmonary fibrosis in sarcoidosis.

URL:	https://www.eurorad.org/case/11345
DOI:	10.1594/EURORAD/CASE.11345
ISSN:	1563-4086