Gastrointestinal stromal tumor mimicking perineurioma: A case report

Abstract

Although gastrointestinal stromal tumor (GIST) can present with various histological characteristics, GIST mimicking perineurioma has not been previously reported. We present the case of a 47-year-old woman diagnosed with GIST after laparoscopic resection of a stomach tumor near the lesser curvature of the gastric body close to the cardia. Morphological features resembled a perineurioma. c.1504_1509 (p.A502_Y503) duplication was found in exon 9 of kinase insert domain receptor (c-KIT). This specific mutation is associated with constitutive activation of the c-KIT, which is crucial in the pathogenesis of GIST. Such unique histological characteristics broaden our understanding of the morphological diversity within GISTs and underscore the importance of considering an extended differential diagnosis when encountering atypical gastrointestinal tumors. This rare presentation may challenge conventional diagnostic criteria and could influence therapeutic strategies, emphasizing the need for comprehensive histological and molecular assessments in patient management.

Keywords: Gastrointestinal stromal tumor; Immunohistochemistry; Molecular pathology.

Figure 1:

(a) Abdominal computed tomography with contrast enhancement showed a mass near the cardia on the lesser curvature side of the gastric body (blue arrow). (b) The tumor was nodular and measured 3 × 2.3 × 1.7 cm.

Figure 2:

(a) Histopathologically, the tumor was composed of nodules of different size in a stromal background (red arrow, ×10). (b) Tumor cells were distributed at an uneven density and the stroma was hyalinized with mucinous degeneration (yellow arrow, ×15). (c) Tumor cells were spindle arranged in a perineurium-like pattern (green arrow, ×30). (d-h)Tumor tissue was immunohistochemically positive (×20) for cluster of differentiation 117, discovered on gastrointestinal stromal tumor-1, cluster of differentiation 34, succinate dehydrogenase iron-sulfur subunit B, and smooth muscle actin. (i)The Ki-67 antigen index was ≤1%. (j-k)Staining for S-100 calcium-binding protein and SRY-box 10 protein was negative. (H&E: Hematoxylin and eosin, CD117: Cluster of differentiation 117, DOG1: Discovered on gastrointestinal stromal tumor-1, CD34: Cluster of differentiation 34, SDHB: Succinate dehydrogenase iron-sulfur subunit B, SMA: Smooth muscle actin, Ki-67 index: Ki-67 antigen index, S-100: S-100 calcium-binding protein, SOX-10: SRY-box 10 protein).

Figure 3:

(a-b) Forward and reverse Sanger sequencing demonstrated c.1504_1509 (p.A502_Y503) duplication in exon 9 of Kinase Insert Domain Receptor (red arrow). (c-d)Forward sequencing of exon 12 and exon 18 of platelet-derived growth factor receptor alpha showed no mutation. (A: Adenine, C: Cytosine, T: Thymine, G: Guanine, K: G or T (keto bases), Y: C or T (pyrimidine bases).