Synchronous and metachronous metastasis to renal parenchyma of esophageal squamous cell carcinoma: two case reports and review of the literature.

Metastasis of esophageal squamous cell carcinoma (ESCC) spread to uncommon sites is increasing in recent years. Metachronous renal metastasis of ESCC was reported before and relatively easy to be diagnosed. But synchronous renal parenchyma metastasis of ESCC is rare and of importance before make treatment plan. Here we present one case of synchronous and one case of metachronous renal parenchyma of ESCC. In the synchronous renal metastasis case, the patient was diagnosed ESCC in August 2016. Though CT scan was normal, PET-CT scan found a small lesion in right renal cortex with increased FDG uptake. The patient refused biopsy of renal lesion. Two cycles of neoadjuvant chemotherapy were given with stable response. Then esophagectomy and adjuvant radiation were given. Seven months later, CT scan revealed renal and spleen lesions and biopsy confirmed squamous cell carcinoma. The patient refused systematic treatment and died 5 months later. In the metachronous renal metastasis case, the patient was diagnosed ESCC in March 2015 and PET/CT scan showed no distant metastasis. Esophagectomy and adjuvant radiotherapy were given. CT scan revealed solitary renal and multiple lung metastasis 23 months later. Biopsy of renal lesion confirmed squamous cell carcinoma (SCC). Chemotherapy was given but with only stable response. The patient died 7 months later after relapse. Both patients had not urinary symptoms. Together with published literatures, renal parenchyma metastasis of ESCC is often asymptomatic. Disease history and biopsy are helpful in diagnosis. And present cases suggested that PET-CT is more sensitive than CT to identify unusual metastasis of ESCC.