Solitary mediastinal lymph node metastasis in rectosigmoid carcinoma: a case report

Abstract

Introduction: Colorectal cancer most commonly metastasizes to the regional lymph nodes, liver, bone, lung, and brain. Metastases to mediastinal lymph nodes is a rare entity which has never been reported to be solitary.

Case report: We herein describe a 67-year-old male patient with a solitary mediastinal lymph node metastasis three years following the resection of his primary rectosigmoid carcinoma. Pathological characteristics of the metastatic tissue and technical limitations in imaging modalities resulted in incongruity between follow-up CT and PET scans. Diagnosis of this distant metastasis has been confirmed through a mediastinoscopic biopsy.

Conclusion: Attention should be paid to the mediastinum when evaluating PET scan or CT films during follow-up of patients with colorectal cancer. Using PET/CT instead of separate morphological and functional data sets favors better detection. Questions still remain concerning the ideal management protocol of such a presentation, the two main options being locoregional or chemotherapeutic.

Figure 1

Colonic tissue in paratracheal nodes. Paratracheal nodal involvement by metastatic adenocarcinoma (A) [H&E, 200×]. The tumor cells are strongly positive for CK20 (B) [400×], weakly positive for CK7 (C) [400×]. Micrometastasis in another paratracheal lymph node (D) [400×].

Figure 2

PET scan of thorax. ¹⁸F-FDG PET scan of the thorax showing a 2.2 cm enlarged right paratracheal lymph node.