Diffuse Sarcoidosis Masquerading as Widespread Malignant Disease: A Rare Case Report and Literature Review.

Sarcoidosis is a multisystem granulomatous disease commonly involving the lungs and mediastinal lymph nodes with the exact etiology being unclear. The simultaneous presence of malignant disease such as breast cancer and sarcoidosis has been reported. Sarcoidosis preceding a diagnosis of malignancy and that occurring years after treatment of malignant disease has been noted in the past. The presence of sarcoidosis in the setting of malignant disease carries a high risk of misdiagnosis. In this article, we report the case of a 45-year-old female with stage IA invasive ductal carcinoma of left breast that was in remission for 2 years; however, radiological imaging including magnetic resonance imaging of thoracic spine and positron emission tomography-computed tomography scanning were highly suspicious for malignant disease metastasis versus lymphoma with the widespread lymphadenopathy. Multiple tissue biopsies with histopathological evaluation allowed us to definitively exclude malignant disease metastasis and to correctly diagnose her atypical presentation of sarcoidosis.