Clinical History
A 52-year-old female patient presented with breathlessness on exertion for 3 months. She also complained of dry cough for a month which did not respond to antibiotics. There was no history of haemoptysis, cough with expectoration or chest pain.
Imaging Findings
Radiograph of chest (Fig. 1) revealed reticulo-nodular pattern with infiltrates in right perihilar region and left mid zone. Few nodular opacities are also seen in left upper zone and adjacent to left costo-phrenic angle. Further evaluation with plain and post-contrast enhanced HRCT scan of the chest was performed.
The findings included:
- Multiple enlarged, homogeneous mildly enhancing nodes in the mediastinum in pretracheal, right paratracheal, prevascular, bilateral hilar and subcarinal locations (Fig. 2).
- Non-enhancing, ill-defined soft tissue masses in bilateral perihilar areas extending to the peripheral lung (Fig. 3).
- Diffuse thickening of peribronchovascular interstitium along with sharp well-defined nodules (Fig. 5, 7).
- Multiple well-defined nodules in subpleural, fissural location and along the interlobar interstitium (Fig. 5, 6, 7).
- Sarcoid cluster - consisting of cluster of multiple micro nodules was also seen in the right lower lobe. (Fig. 8)
- Multiple hypoenhancing lesions in both lobes of the liver (Fig. 4).
Discussion
- Sarcoidosis is a chronic, immune-mediated multi-system inflammatory disorder of unknown aetiology characterized by non-caseous epitheloid granulomas most commonly involving the lung and mediastinal/hilar lymph nodes which thus accounts for most of the mortality and morbidity associated with this condition [1].
- The patient may be asymptomatic and sarcoidosis may be suspected incidentally on routine chest radiography when bilateral hilar and right paratracheal fullness due to nodal enlargement is noted.
Patients may present with respiratory complaints such as cough, dyspnoea, chest pain, haemoptysis or non-specific symptoms like fever, fatigue, weight loss.
- The most common finding in sarcoidosis is that of enlarged intrathoracic lymphadenopathy and it typically manifests as bilateral symmetric hilar adenopathy with right paratracheal adenopathy; occurring in almost 85% of patients [2]. The nodes show homogeneous enhancement without necrosis differentiating it from tuberculosis/malignancy. Occasionally calcification may be seen in these nodes which may be amorphous, punctate or egg-shell type [2].
- High-resolution CT (HRCT) is the imaging modality of choice for detecting minute parenchymal details in pulmonary sarcoidosis. It helps in distinguishing active inflammatory changes of nodules, ground glass and alveolar opacities from honeycomb-like cysts, bullae, broad and coarse septal bands, architectural distortion, volume loss, and traction bronchiectasis which indicate irreversible fibrosis in patients with sarcoidosis [1].
- CT features of pulmonary sarcoidosis include interlobular septal thickening, reticulonodular infiltrates and mass-like consolidations. The non-caseating granulomas seen in pulmonary sarcoidosis have a propensity for forming along lymphatics of interstitial tissues in peribronchial, perivascular, subpleural spaces and along fissures. The nodules are sharply defined, small and show upper and middle lobe predominance. Nodular irregular thickening of peribronchovascular interstitium is also seen. Sarcoid cluster is a cluster of multiple micronodules seen along lymphatics in peripheral lung.
Fibrotic changes are characterised by architectural distortion, volume loss, tractional bronchiectasis, coalescent fibrotic perihilar or parenchymal masses.
Fibrocystic changes of bullae, honeycomb cysts indicate advanced stage of sarcoidosis.
- The Siltzbach classification system (Radiological classification of Intrathorvacic changes) [3]
stage 0, normal appearance at chest radiography
stage I lymphadenopathy only
stage II lymphadenopathy and parenchymal lung disease
stage III parenchymal lung disease only
stage IV with pulmonary fibrosis
Diagnosis is by biopsy from enlarged mediastinal adenopathy or lung lesions which shows non-caseating granulomas. Angiotensin converting enzyme (ACE) is elevated and correlates with disease activity. The CD4:CD8 ratio in the blood serum is commonly decreased [2].
Treatment is with corticosteroids.
Differential Diagnosis List
Sarcoidosis
Tuberculosis
Silicosis
Pneumoconiosis
Lymphoma