Persistent Lymph Node Metastasis Post Imatinib Treatment in Low Grade Gastrointestinal Stromal Tumor with PDGFRA Mutation

Belinda Sun,Sarah K Daley,Peter Wanes

doi:10.31487/j.ajscr.2020.03.10

Abstract

Background/Aims: Lymph node metastasis has been considered very rare in gastrointestinal stromal tumors (GIST), especially in low grade GIST. Thus, lymphadenectomy is not required routinely as standard of care during surgery for GIST unless there is suspicion for lymph node metastasis. However, herein we present a low grade PDGFRA mutated GIST status post imatinib chemotherapy with nearly complete response in the primary tumor but a persistent lymph node metastasis which significantly affected the management of the patient. Case Report: A 38-year-old male presented with a 11.5 cm epigastric GIST status post imatinib (Gleevec) treatment who underwent partial gastrectomy with tumor excision. The initial biopsy showed epithelioid type GIST with a low mitotic rate and PDGFRA gene mutation detected by genetic analysis. The original tumor had nearly complete response to imatinib with a few possible residual tumor cells identified; however, one lymph node was found to be positive for metastatic GIST with minimal treatment effect present. The patient was managed with continuous imatinib treatment and life-long follow up. Conclusion: This case raises the awareness of the possibility of lymph node metastasis in low grade conventional GIST with PDGFRA mutation. Lymph node examination may need to be considered as standard of care for better management of patients with GIST.

Highlights

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract
We have reported a case of gastric low-grade epithelioid GIST post imatinib and surgical therapy which was found to have metastasis in a lymph node to emphasize the importance of lymph node examination in the management of patients with GIST
GISTs are a distinctive subgroup of gastrointestinal mesenchymal tumors which are driven by specific gene mutations

Summary

Introduction

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. GIST accounts for 2.2% of malignant gastric tumors in the National Cancer Institute SEER incidence database. A tyrosine kinase inhibitor, imatinib (Gleevec), which blocks KIT proteins, is the main agent for targeted adjuvant and neoadjuvant treatment as well as used for palliation. Risk assessment after surgical resection determines the need for adjuvant imatinib treatment. Main indications for adjuvant imatinib treatment are unresectable or metastatic disease [9]. We have reported a case of gastric low-grade epithelioid GIST post imatinib and surgical therapy which was found to have metastasis in a lymph node to emphasize the importance of lymph node examination in the management of patients with GIST. A 38-year-old male presented with a mass in his abdomen for one year.

Pathology Examination

Microscopic Examination

Findings

Discussion