S1867 Rectal and Esophageal Granular Cell Tumors; A Report of Two Cases

Abstract

Introduction: Granular cell tumors (GCT) are a predominantly benign tumor arising from mesenchymal origin - specifically Schwann cells. They typically appear as a solitary mass; in the gastrointestinal tract (GIT), they can present as a painless yellow-gray polyp or nodule. It is more commonly found in women ages 10-50 years old. They can arise in any location, most commonly from the skin, and only 10% found in the GIT. Within the GIT, the esophagus is the most common location while the rectum is the rarest location. Case description/methods: Case #1: Patient is a 51-year-old female with no significant past medical history coming in with right upper quadrant (RUQ) abdominal pain. Pain has been present for 1 month prior to seeking medical attention. Pain is not consistently associated with eating food. There is no associated nausea, vomiting, diarrhea, or constipation. EGD was performed at that time and revealed a white localized plaque (image 1A). Histopathology on H&E stain revealed esophageal mucosa with underlying sheets of epithelioid cells with abundant granular eosinophilic cytoplasm (image 1B). S100 stain was positive, but MART1 and SOX10 were negative. Case #2: Patient is a 64-year-old male with a past medical history significant for aortic stenosis who presented for his first screening colonoscopy. At that time, colonoscopy revealed mild erythematous mucosa in the terminal ileum and sigmoid colon as well as a small mass in the rectum (image 1C). Biopsy results revealed focal active colitis in the sigmoid colon and a rectal granular cell tumor in the rectum. Histopathology of the tumor revealed colorectal mucosa with packets of uniform epithelioid cells with abundant eosinophilic granular cytoplasm interdigitating with the colonic crypts on H&E stains (Image 1D). S100 immunohistochemistry stain demonstrated diffuse expression within the granular cell tumor with absent staining in crypt epithelium (Image 1E-F). MART1 and SOX10 were negative as well. Discussion: GCTs are rare tumors ad account for 0.5% of all soft tissue tumors. Only 10% occur in the GIT and rarely in the rectum. Most are benign with only 1-2% being malignant. If ulceration is found, malignancy should be ruled out. It is also important to differentiate them from other tumor occurring in the GIT such as neurogenic and gastrointestinal stromal tumors. It is also important to differentiate them from melanomas as they stain positive for S100; melanoma specific stains, such as MART1 and SOX10, are used to differentiate them.Figure 1.: (A) White localized plaque in the esophagus. (B) Esophageal mucosa with underlying sheets of epithelioid cells with abundant granular eosinophilic cytoplasm. (C) Small yellowish mass in the rectum. (D) H&E stain revealing colorectal mucosa with packets of uniform epithelioid cells with abundant eosinophilic granular cytoplasm interdigitating with the colonic crypts. (E) S100 immunohistochemistry stain demonstrating diffuse expression within the granular cell tumor with absent staining in crypt epithelium. (F) Rectal granular cell tumor negative for MART1 and SOX10 at 20x magnification.