Small submucosal tumors of the stomach: differentiation of gastric schwannoma from gastrointestinal stromal tumor with CT

Abstract

Objective: To identify the CT features that help differentiate gastric schwannomas (GS) from small (5 cm or smaller) gastrointestinal stromal tumors (GIST) and to assess the growth rates of both tumors.

Materials and methods: We included 16 small GSs and 56 GISTs located in the stomach. We evaluated the CT features including size, contour, surface pattern, margins, growth pattern, pattern and degree of contrast enhancement, and the presence of intralesional low attenuation area, hemorrhage, calcification, surface dimpling, fistula, perilesional lymph nodes (LNs), invasion to other organs, metastasis, ascites, and peritoneal seeding. We also estimated the tumor volume doubling time.

Results: Compared with GISTs, GSs more frequently demonstrated a homogeneous enhancement pattern, exophytic or mixed growth pattern, and the presence of perilesional LNs (each p < 0.05). The intralesional low attenuation area was more common in GISTs than GSs (p < 0.05). Multivariate analyses indicated that a homogeneous enhancement pattern, exophytic or mixed growth pattern, and the presence of perilesional LNs were statistically significant (p < 0.05). Tumor volume doubling times for GSs (mean, 1685.4 days) were significantly longer than that of GISTs (mean, 377.6 days) (p = 0.004).

Conclusion: Although small GSs and GISTs show similar imaging findings, GSs more frequently show an exophytic or mixed growth pattern, homogeneous enhancement pattern, perilesional LNs and grow slower than GISTs.

Keywords: CT; Gastric tumor; Gastrointestinal submucosal tumor; Schwannoma; Stomach; Submucosal tumor.

Fig. 1

Gastrointestinal stromal tumors in gastric upper body of 57-year-old man. Transverse CT scan shows well-defined, round mass with heterogeneously moderate enhancement (arrow) in gastric upper body. Tumor reveals endoluminal growth pattern. There is no intralesional low attenuation area, calcification, or surface dimpling.

Fig. 2

Gastric schwannomas in gastric midbody of 62-year-old woman. Transverse CT scan shows well-defined round mass with homogeneously moderate enhancement (arrow) in gastric midbody. Tumor reveals exophytic growth pattern. There is no intralesional low attenuation area, calcification, or surface dimpling.

Fig. 3

Gastric schwannomas in gastric lower body of 63-year-old woman. Transverse CT scan shows well-defined, round mass with homogeneously moderate enhancement (arrow) in gastric lower body. Tumor reveals mixed (endoluminal and exophytic) growth pattern. There is no intralesional low attenuation area, calcification, or surface dimpling.

Fig. 4

GIST in gastric cardia of 72-year-old woman. Coronal CT scan shows irregular-surfaced round mass with heterogeneously moderate enhancement (arrow) in gastric lower body. Tumor reveals mixed (endoluminal and exophytic) growth pattern and intratumoral calcification. There is no intralesional low attenuation area or surface dimpling.

Fig. 5

GIST in gastric lower body of 58-year-old woman. Transverse CT scan shows well-defined round mass with moderate enhancement (arrow) in the gastric midbody. Mass reveals mixed (endoluminal and exophytic) growth pattern and central intralesional low attenuation area (i.e., necrosis).

Fig. 6

Gastric schwannomas in gastric upper body of 65-year-old woman. A. Transverse CT scan shows well-defined round mass with homogeneous enhancement (arrow) in gastric upper body. Tumor volume is 4200 mm³. B. Transverse follow-up CT scan obtained 24 months after initial CT scan shows 5720 mm³ tumor volume. This tumor (arrow) has 1673-day tumor volume doubling time. C. Transverse CT scan shows perilesional lymph node (arrow).

Fig. 7

Gastrointestinal stromal tumors in gastric upper body of 81-year-old woman. A. Coronal CT scan shows well-defined lobulated mass with heterogeneous enhancement (arrow) in gastric upper body. Tumor volume is 1610 mm³. B. Coronal follow-up CT scan obtained 12 months after initial CT scan shows 12035 mm³ tumor volume of. This tumor (arrow) has 127-day tumor volume doubling time.