Teaching Case

A 67-year-old Asian male with a history of renal cell carcinoma (RCC) presents for surveillance imaging. He underwent left-sided nephrectomy 31 months ago and was found to have metastatic disease in the lungs four months later. He began neoadjuvant chemotherapy with partial response and has remained asymptomatic since diagnosis.

Computed tomography (CT) of the chest, abdomen and pelvis at 31 months after nephrectomy revealed interval growth of prior lung nodules and a new hyperdense lesion protruding into the lumen of the distended stomach. Focused retrospective review of surveillance CT at 19 months after nephrectomy did not reveal evidence of a gastric lesion, however, images at 25 months after nephrectomy demonstrated a small enhancing lesion within the collapsed gastric folds (Figure 1).

Subsequent upper endoscopy revealed a solitary pedunculated 3.5 cm gastric polyp in the stomach fundus that was completely resected using snare cautery. Tissue samples were sent for histopathology which demonstrated clear cytoplasm, compact to alveolar architecture, and a thin-walled vascular network (Figure 2). Renal cell carcinoma marker and PAX-8 immunohistochemical stains were also positive (Figure 2).

Background

Clear cell RCC most commonly metastasizes to the lungs, bones, or distant lymph nodes, however it has the potential to spread to any site in the body[1]. Gastric metastasis of RCC is a rare event and the incidence is estimated to be as low as 0.2% in clinical practice[2]. The timeline for gastric metastasis in RCC is sporadic and can occur soon after discovery of the primary tumour or many years after nephrectomy[3].

Clinical Perspective

RCC is a highly vascular tumour; therefore, these lesions confer an increased risk of spontaneous haemorrhage [4]. For this reason, patients with gastric metastasis usually present with anaemia, abdominal discomfort, melena, or hematemesis[5]. However, in our case the metastatic lesion was found incidentally during active surveillance imaging for lung metastasis.

Imaging Perspective

The current standard of care for RCC surveillance is CT with IV contrast to assess the primary tumour size, local invasion, regional lymph node spread, or distant metastasis[6]. The collapsed stomach may not allow adequate visualization of potential metastatic lesions in the gastric mucosa, which are typically solitary and polypoid in shape[7]. For this reason, administration of negative oral contrast (water, VoLumen, or Breeza) to distend the gastric contents would optimize chances of early detection. Ultimately, endoscopic biopsy and histopathology are indicated for definitive diagnosis.

Outcome

Although the prognosis for patients with gastric metastasis from RCC is poor, therapeutic intervention with endoscopic metastectomy or protein kinase inhibitor therapy have shown to reduce complications of later disease[2]. Long term survival after treatment varies based on the degree of metastatic disease, therefore, the costs and benefits of intervention should be considered on a case-by-case basis.

Take-Home Message

RCC may spread to any organ, including the gastrointestinal tract. The rare event of gastric metastasis is highlighted. Administration of negative oral contrast during surveillance CT imaging may improve earlier detection of gastric metastasis in these patients. Earlier detection of gastric disease may reduce the risk of haemorrhage or perforation and improve a patient’s quality of life.

Written informed patient consent for publication has been obtained.