[Phenotypic Change in a Gastric GIST after NAC‒Imatinib-A Case Report]

Area of Science:

• Gastroenterology
• Surgical Oncology
• Pathology

Background:

• Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract.
• Neoadjuvant chemotherapy (NAC) is increasingly used for GIST management, but its impact on histopathological features is not fully understood.
• Accurate diagnosis of GIST relies on characteristic histopathological findings and immunohistochemical (IHC) staining.

Purpose of the Study:

• To report a challenging case of GIST diagnosis following NAC.
• To review the literature on IHC changes in GIST after NAC.
• To emphasize the importance of considering post-treatment alterations in histopathology.

Main Methods:

• Case presentation of a 53-year-old male with epigastric pain and a submucosal tumor.
• Initial diagnosis of GIST based on gastroscopy, biopsy, and IHC (c-kit positive).
• Surgical resection after NAC, followed by detailed histopathological analysis of the resected specimen.

Main Results:

• Initial biopsy diagnosed GIST with spindle cell proliferation and c-kit positivity.
• Post-NAC histopathological findings of the resected specimen differed significantly from the biopsy.
• Complete resection was achieved, but postoperative diagnosis was complicated by altered histology.

Conclusions:

• Neoadjuvant chemotherapy can markedly alter GIST histopathology, posing diagnostic challenges.
• There is a paucity of literature on IHC changes in GIST following NAC.
• This case underscores the need for careful interpretation of post-NAC specimens and further research into treatment-induced histological modifications.