Sarcoid-Like Lesions Mimicking Pulmonary Metastasis: A Case Series and Review of the Literature

Background: The association of sarcoid-like lesions and malignancy is well described. Nonetheless, pulmonary lesions in malignant disease are typically presumed metastatic, and do not routinely receive histological validation. Here, we report on pulmonary sarcoid-like lesions identified in patients with a primary malignancy where pulmonary metastatic disease was suspected.

Methods: Patients who underwent thoracic surgical procedures for confirmation or treatment of suspected pulmonary metastasis were retrospectively analysed.

Results: In 8/186 patients (4.3%), histology revealed sarcoid-like lesions. In these cases, there were no clinical symptoms suggestive of sarcoidosis. All underlying primary malignancies in the sarcoid-like patients were treated with curative intent. The median age of patients with sarcoid-like lesions was 46.3 years (range 26-61). The median interval between primary diagnosis of malignancy and diagnosis of pulmonary lesions was 188 days (range 0-794), with thoracic surgical intervention performed at a median of 250 days (range 183-675). FDG-avidity was demonstrated in the sarcoid-like lesions in 2 out of 3 patients who underwent PET-CT.

Conclusion: Sarcoid-like lesions may be challenging to identify and can mimic pulmonary metastases. Therefore, considering sarcoidosis as a differential diagnosis whenever first pulmonary metastasis is suspected is warranted. Carefully considered, histological validation of initial suspected pulmonary metastasis may avoid subsequent over- or undertreatment.