Sarcoidosis is a systemic disorder of unknown etiology, which is characterized by non-caseating granuloma reaction.1 There are contradictory data in the literature regarding the relationship between sarcoidosis and malignancy.2 The reasons of those controversial results may be explained with biases in patients selection and different classification method used. Herein we reported the incidence of malignancy in a small cohort sarcoidosis patients.

Our study is a retrospective analysis of 131 patients diagnosed with sarcoidosis at the single Rheumatology center. Sarcoidosis diagnosis was made through clinical, laboratory, radiologic and histopathological investigations. The incidence of malignancies was investigated in this cohort. Malignant diseases were diagnosed by histopathology. The clinical data of patients with sarcoidosis and malignant diseases were further analyzed. Six (4.6%) patients with malignant diseases were identified in our cohort. Hodgkin lymphoma (HL) was detected in 3 patients, followed by one patient with breast, thyroid and testicular cancer. Five patients had chronic sarcoidosis with pulmonary involvement, and one patient presented as Löfgren's syndrome. HL developed concomitantly with sarcoidosis in one patient while other two patients developed disease before and after sarcoidosis diagnosis. Sarcoidosis presented prior to the malignancy in 2 of 6 patients (Table 1). Among 6 sarcoidosis–malignancy patients 4 were female and 2 were male, the mean age was 45.6 years and mean disease duration was 3.8 years (1–12 years). All 6 patients had pulmonary involvement, 5 patients had arthritis, and one patient had uveitis. On laboratory tests, all 6 patients had elevated acute phase reactants, while 3 patients had elevated serum ACE levels. In terms of current drug usage, 4 patients received low-dose corticosteroids, and two patients received hydroxychloroquine. All 6 sarcoidosis–malignancy patients were survived during six year follow-up.

Our study showed no significant association between sarcoidosis and malignancy. Only 6 (4.6%) patients with malignant diseases were identified in our cohort of 131 patients with sarcoidosis. Our results were with concordance with previously reported data. There are conflicting results in the literature regarding the relationship between sarcoidosis and malignancy.3 Yamaguchi et al. evaluate the excess mortality in a cohort of 1411 cases of sarcoidosis for a period of 3 years using the standardized mortality ratio (SMR).4 They reported that lung cancer, leukemia and uterine cancer showed a statistically significant SMR. Kataoka et al. observed a significantly greater than expected incidence of thyroid and laryngeal cancer and leukemia in sarcoidosis patients.5 Boffetta et al. reported the increased incidence of colon and kidney cancer in sarcoidosis patients in USA.6 Moderate association between sarcoidosis and malignancy was showed in a meta-analysis study.7 The authors reported two-fold higher risk of developing skin and hematopoietic cancers while there was not a significant increase in risk of lung cancer. The low prevalence of smoking in sarcoidosis patients may be a reason for the lack of an association between lung cancer and sarcoidosis. Ungprasert et al. investigated the incidence of malignancy in patients with sarcoidosis and not found any significant association.8 The exact mechanism which may explained the association between sarcoidosis and malignancy is not fully understood. Immune dysregulation and chronic inflammation seen in sarcoidosis may be a risk factor for malignancy development.9 Activation of Th1/Th17 cells, released of some proinflammatory cytokines, impared CD4 T-cells and decreased regulatory T cells, may promote angiogenesis, cells proliferation, stromal growth, and tissue remodelling.10

We found low incidence of malignancy in patients with sarcoidosis in our small cohort. On the basis of the available data, the association between sarcoidosis and malignancy is still under debate. More prospective studies are needed in this regard.

The authors declare no conflict of interests.