Differential diagnosis of gastrointestinal stromal tumors versus leiomyomas by special stains

Abstract

The objective of the study was to investigate whether special stains can differentiate gastrointestinal stromal tumors (GISTs) and gastrointestinal leiomyomas (GILs). In this retrospective study, 39 cases of GISTs (diameter, 0.2-8.8 cm) and 75 cases of GILs (diameter, 0.2-4.5 cm) were recruited, all biopsy specimens were obtained by endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) excision, and the depth of excision included the whole mucosa, mucosal myometria, and most submucosa. GISTs and GILs were the most common types of mesenchymal tumors found anywhere along the gastrointestinal (GI) tract, from the esophagus to the rectum. GISTs were often associated with a higher risk of malignancy. In this study, the gender, age of onset, size and sites of the lesions, together with the number of mucosal or lamina propria lesions all have significant differences, nevertheless, there was no significant difference in cell morphology of GISTs and GILs tested by hematoxylin eosin (H&E) stain, and all showed low echo areas by EUS examination. In this retrospective study, the GISTs and GILs had been diagnosed by immunohistochemistry combined with clinical morphology. Subsequently, special stains including Masson's trichrome (MT) stain, Alcian blue periodic acid-Schiff (AB-PAS) stain (pH 2.5), Wright-Giemsa (W-G) stain and periodic acid-Schiff (PAS) combined with diastase periodic acid-Schiff (D-PAS) stains were also applied in the diagnosis, the retrospective study results showed that 92.3% GISTs were stained blue with MT stain, 97.3% GILs were stained red with MT stain (P < 0.01), almost all GISTs were PAS-negative (light purple), in contrast, all GILs were PAS-positive (rose red) (P < 0.01), all of these experiments set control using the blood vessels stained by MT and AB-PAS stains. Nevertheless, there was no significant difference between GISTs and GILs stained by W-G stain. These obvious and meaningful differential results were also confirmed in the detection of new GISTs and GILs cases using MT and AB-PAS stains. In conclusion, MT and AB-PAS stains could also identify GISTs and GILs cases, particularly, AB-PAS was more sensitive and more specific, providing a more cost-effective, simple, and high sensitivity and specificity inspection methods, which should be noticed and widely used in the future, especially in resource-limited grass-roots testing institution or in cases with inconclusive immunostains or insufficient material.

Keywords: Gastrointestinal leiomyoma; Gastrointestinal stromal tumor; Malignancy; Special stain.

Fig. 1

Hematoxylin eosin stain and Immunohistochemical diagnosis GISTs. A H&E staining in cardia of stomach GIST. B-D The characteristic markers of stromal tumors such as CD117 (B) and DOG1 (C) were diffuse strong positive, but negative for S-100 (D) in cardia of stomach GIST. E H&E staining in fundus of stomach GIST. F-H CD117 (F) and DOG1 (G) were diffuse strong positive, but negative for S-100 (H) in fundus of stomach GIST. I H&E staining in small intestine GIST. J-L CD117 (J) and DOG1 (K) were diffuse strong positive, but negative for S-100 (L) in small intestine GIST. (Magnification: 200 ×).

Fig. 2

Hematoxylin eosin stain and Immunohistochemical diagnosis GILs. A H&E staining in esophagus GIL. B-D The characteristic markers of smooth muscle such as SMA (D) were diffuse strong positive, but were negative for CD117 (B) and DOG1 (C). E H&E staining in body of stomach GIL. F-H). CD117 (F) and DOG1 (G) were negative, but diffuse strong positive SMA (H) in body of stomach GIL. I H&E staining in rectum GIL. J-L CD117 (J) and DOG1 (K) were negative, but diffuse strong positive SMA (L) in rectum GIL. (Magnification: 200 ×).

Fig. 3

Special stains including MT, AB-PAS, W-G diagnosis GISTs. A-C GIST in cardia was stained red (A) by MT stain, AB-PAS stain was PAS-negative (B), (C) was W-G stain. D-F GIST in fundus of stomach was stained blue (D) by MT stain, AB-PAS stain was PAS-negative (E), (F) was W-G stain. G-I GIST in small intestine was stained blue (G) by MT stain, AB-PAS stain was PAS-negative (H), (I) was W-G stain. (Magnification: 200 ×).

Fig. 4

Special stains including MT, AB-PAS, W-G diagnosis GILs. A-C GIL in esophagus was stained red (A) by MT stain, AB-PAS stain was PAS-positive (B), (C) was W-G stain. D-F GIL in body of stomach was stained red (D) by MT stain, AB-PAS stain was PAS-positive (E), (F) was W-G stain. G-I GIL in rectum was stained red (G) by MT stain, AB-PAS stain was PAS-positive (H), (I) was W-G stain. J-K The control of muscle fibers of the blood vessels are stained red by MT stain (J), PAS positive in (K), all as shown by the red arrow. The collagen fibers around the blood vessels are stained blue by MT stain as shown by the black arrow in (J) and PAS negative as shown by the black arrow in (K). (Magnification: 200 ×).

Fig. 5

Statistical analysis of the results of special stain and IHC diagnosis. A The bar chart showed about 92.3% of GISTs were stained blue with MT stain. B All of the GISTs were negative for AB-PAS stain. C-D CD117 (C) and DOG1 (D) were diffuse strong positive in almost all GISTs. E 97.3% of GILs were stained red with MT stain. F Almost all GILs were positive for AB-PAS stain. G-H CD117 (G) and DOG1 (H) were negative in all GILs. (“***” indicates P < 0.001 with significant difference.)

Fig. 6

The flow chart for differential diagnosis GISTs versus GILs by IHC and special stains, including MT and ABPAS stains. Generally, GISTs were DOG 1 and CD117 diffuse strong positive, yet, Desmin was absolute negative, and SMA was negative or positive in several GISTs cases, for GILs, Desmin and SMA were diffuse strong positive, yet, DOG 1 and CD117 were absolute negative. Furthermore, New diagnostic methods, GISTs were blue by MT stain, and AB-PAS negative (light purple), on the contrary, GILs were red by MT stain, and AB-PAS positive (rose red). MT and AB-PAS stain all could can be identified GISTs and GILs instead of IHC stain, individually. Whereas, AB-PAS stain might be much more sensitive than MT stain.