P1006 - A Rare Case of Gastric Schwannoma in Asymptomatic Patient

Sreekanth Avula, MD¹, Rahul Rauniyar, MBBS¹, Mahesh Cheryala, MD¹, Abdul Ahad Ehsan Sheikh, MD¹, Rohit Rauniyar, MBBS^2
1Wright Center for GME, Scranton, PA; ²McLaren Flint, Flint, MI

Introduction: Schwannomas, also known as neuromas or neurilemomas are the most common benign tumors of peripheral nerves. It can occur any where in the body with most common location is intracranial called as Vestibular schwannoma/Acoustic neuroma. We present a unique case of Gastric Schwannoma, in asymptomatic patient.

Case Description/Methods: A 65 year old male with past medical history of tobacco use presented with mass in the gastric region found incidentally during routine CT lung scan. During routine CT Lung scan patient was found to have 4 cm homogeneous mass arising from lesser curvature aspect of gastric body which wasn’t present 6 months back. CT abdomen and pelvis w/wo contrast was ordered which showed 4.3 x 3.8 x 4.3 cm exophytic smooth solid enhancing lesion arising from gastric fundus. Patient later underwent Upper GI Endoscopy with Endoscopic ultrasound which revealed heterogeneous hypoechoic mass arising from muscularis propria with no cystic degeneration, regional adenopathy. Fine needle aspiration of the mass was done. Preliminary cytology results were consistent with GIST and sent for histopathology and immunostaining for confirmation. HPE showed bland spindle cells, with elongated, pointed nuclei, mild nuclear atypia, nuclear palisading, and prominent whirling pattern. Lesional cells were positive for S100 and Sox 10 immunostains, compatible with a benign schwannoma. Ki-67 immunostain shows very low proliferative index, of less than 1%. Immunostains were negative for CD117, PanKeratin, Actin, Mart1 and HMB45.

Discussion: Schwannoma also sometimes called as Neuroma or neurilemmoma are rare benign tumors arising from Schwann cells of nerve sheaths of peripheral nerves. Schwannoma arising for gastrointestinal tract is rare with stomach being the most common location. Gastric schwannoma comprises of < 0.2% of gastric neoplasm. They usually occur in any age but more predominant in middle-aged women. They are usually benign with overall good prognosis and low recurrence rates, malignant potential do exist but rare. The diagnosis of schwannoma is based on tissue histology with further confirmation by immuno-histochemical markers. Immuno-histostain shows strong staining for S100 and negative for CD117, PanKeratin, Actin, HMB45 and Mart1. They are commonly misdiagnosed as GIST, hence differentiating by Histopathology and Immunostains is very important because their management is different.


Figure: Figure A - Endoscopic view of mass Figure B - CD117 Negative Figure C - S-100 Positive Figure D - Sox1 Positive

Condition	Marker Positive
Schwannoma	S-100 , Sox10
GIST	CD117
Melanoma	HMB45 , Mart1
Spindle cell Carcinoma	PanKeratin
Leiomyoma	Actin
Proliferative marker	Ki 67

Table: Table showing different conditions with respective positive markers


Disclosures:
Sreekanth Avula indicated no relevant financial relationships.
Rahul Rauniyar indicated no relevant financial relationships.
Mahesh Cheryala indicated no relevant financial relationships.
Abdul Ahad Ehsan Sheikh indicated no relevant financial relationships.
Rohit Rauniyar indicated no relevant financial relationships.


Sreekanth Avula, MD¹, Rahul Rauniyar, MBBS¹, Mahesh Cheryala, MD¹, Abdul Ahad Ehsan Sheikh, MD¹, Rohit Rauniyar, MBBS². P1006 - A Rare Case of Gastric Schwannoma in Asymptomatic Patient, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.