[Metastasis or sarcoidosis - a diagnostic pitfall in metastatic rectal carcinoma]

Granulomatous diseases as sarcoidosis can impair the staging of metastatic diseases since metastasis are hard to distinguish from granulomas in standard imaging. This case report describes the diagnostic workup and therapy in a patient with simultaneous sarcoidosis and rectal cancer with hepatic metastasis and how a curative stadium was achieved.

A 71-year old male patient was diagnosed with an adenocarcinoma of the rectum after presenting with involuntary weight loss and anemia. Further diagnostics raised strong suspicion of hepatic, pulmonary and splenic metastasis. Histology after bronchoscopy surprisingly discovered non-caseating granulomas, leading to the diagnosis of sarcoidosis. Due to an obstructive tumor, a rectum resection was performed. Due to a high suspicion of splenic metastasis during surgery, the spleen was removed. Histology revealed no metastasis in the spleen but multiple granulomas due to sarcoidosis. After surgery, biopsy of a suspicious lesion in the liver revealed both metastasis and sarcoidosis in the same sample. The patient was treated with a pseudo(neo)adjuvant chemotherapy with 5-Fluorouracil, Leukovorin, Oxaliplatin (FOLFOX) and Panitumumab (Anti-EGF-antibody). After treatment, CT scan revealed two hepatic lesions decreasing in size, while all other lesions were metrically stable. A right hemihepatectomy followed and histology revealed both sarcoidosis and metastasis. The curated patient was sent to aftercare and there is no suspicion for a relapse (13 month after last surgery).

The simultaneous appearance of metastatic tumors and sarcoidosis creates a diagnostic dilemma since both manifestations can barely be distinguished in regular imaging technologies. This case report demonstrates that the histological work-up of affected organs with consecutive resections can cure a patient of a metastatic tumor disease, even in the context of simultaneous sarcoidosis.