A 48-year-old asymptomatic female underwent an abdominal ultrasound due to liver enzymes elevation (AST 45 U/L, ALT 77 U/L) detected on routine evaluation. Abdominal ultrasound revealed an incidental gastric wall lesion that was misinterpreted as A cyst of the pancreatic body measuring 68x45mm. Additional abdominal computed tomography (CT) was performed showing a well-defined, hypodense gastric mass with calcifications, measuring 65mm, on the posterior wall of the distal body, compressing the transverse colon; no lesions were visible on the pancreas or liver. Upper gastrointestinal endoscopy demonstrated a 6cm rounded subepithelial lesion (SEL), with a central depression, on the posterior face of the distal body of the stomach (Fig. 1).
Figure 1. Upper endoscopy: gastric SEL.
On the endoscopic ultrasound (EUS) examination, the gastric lesion corresponded to a well-defined heterogeneous lesion, with solid iso/hypoechoic areas, necrotic/cystic (anechoic) areas and calcifications, located on the fourth layer (muscularis propria) (Fig. 2). Additionally, rounded and hypoechoic perilesional lymph nodes (maximum diameter 14mm) were identified.
Figure 2. EUS: Well-difined heterogeneous with necrotic/cystic areas and calcifications.
EUS-guided fine needle biopsy (FNB) using a 22G needle was performed (two needle passes; AcquireTM Endoscopic Ultrasound FNB Device, Boston Scientific) and the histopathological analyses revealed rare spindle cell tissue fragments, with a fascicular arrangement, without nuclear atypia nor mitosis. Immunohistochemistry staining was positive to S100 and negative to CD117, CD34, DOG 1 and smooth muscle actine (Fig. 3A and 3B).
Figure 3. Pathology: A) rare spindle cell tissue fragments, with a fascicular arrangement (HE; 200x); B) positive S100 immunohistochemistry (200x).
The histopathological features and immunohistochemical staining pattern were consistent with the diagnosis of gastric schwannoma. After multidisciplinary discussion, the patient was submitted to a laparoscopic partial gastrectomy with Roux-en-Y reconstruction, and the histopathological examination of the surgical specimen confirmed the diagnosis (Fig. 4). Evaluation of 9 lymph nodes revealed reactive follicular hyperplasia.
Figure 4. Resected gastric mass after surgery.
Gastric schwannoma (GS) is a rare neoplasm deriving from Schwann cells of the peripheral nerves in the stomach [1]. It accounts for 0.2% of all gastric tumors and malignant transformation risk is low [1,2]. GS typically grows as a solitary lesion, arising most commonly from the body of the stomach (50%), with a variable size [1,2]. GS can occur at any age but is most frequently noted in the fifth to eight decades, with female predominance [1]. GS is often asymptomatic and can be discovered incidentally on cross-sectional imaging, however it can present with non-specific symptoms [2]. On endoscopy it presents as a SEL with no specific characteristics, corresponding to a hypoechoic lesion located on the third or fourth layers on EUS, undistinguished from other SEL, such as gastrointestinal stromal tumor (GIST) or leiomyoma [3]. As a result, these investigations provide only limited information about the tumor, and the definitive diagnosis is determined after histopathological and immunohistochemical examination, obtained, for example, through EUS-guided FNB [2]. Surgical treatment is considered the treatment of choice in patients with GS [2].
Catarina Félix1, Joana Veloso Carmo1, Ana Virgínia Araújo2, Rita Vale Rodrigues3, António Martins2, Martinha Chorão4, Beatriz Costa Neves3, Cláudia Branco2, Cristina Chagas1.