Gastrointestinal Intramucosal Nerve Sheath Neoplasm

Definition

• Gastrointestinal tract mesenchymal neoplasms located primarily in the lamina propria exhibiting features of nerve sheath differentiation, including:
  • Mucosal benign epithelioid nerve sheath tumor
  • Mucosal Schwann cell hamartoma
  • Ganglioneuroma
• Note:  This does not include gastrointestinal tract autonomic nerve sheath neoplasm (GANT), which is covered separately

Diagnostic Criteria

• All three are composed of bland S100 positive cells primarily located in the lamina propria
• When occurring as solitary lesions, none is related to familial syndromes such as:
• Cowden disease
• Multiple endocrine adenomatosis 2
• Neurofibromatosis
• All are benign
• All are overwhelmingly located in the colorectum
• It is not clear if or what is the relation between the three
• Select an individual diagnosis below for full description

Mucosal Benign Epithelioid Nerve Sheath Tumor	Mucosal Schwann Cell Hamartoma	GI Ganglioneuroma
Epithelioid	Spindled	Spindled
No axons	Very rare axons	Axons present
No ganglion cells	No ganglion cells	Ganglion cells present

It is possible that Mucosal Benign Epithelioid Nerve Sheath Tumor and Mucosal Schwann Cell Hamartoma are related
• At least one of the microcystic/reticular schwannomas described by Liegl 2008 was composed of epithelioid cells confined to the lamina propria and thus may fall within the above spectrum

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting :November 29, 2009

Bibliography

• Lewin MR, Dilworth HP, Abu Alfa AK, Epstein JI, Montgomery E. Mucosal benign epithelioid nerve sheath tumors. Am J Surg Pathol. 2005 Oct;29(10):1310-5.
• Gibson JA, Hornick JL. Mucosal Schwann Cell "Hamartoma": Clinicopathologic Study of 26 Neural Colorectal Polyps Distinct From Neurofibromas and Mucosal Neuromas. Am J Surg Pathol. 2008 Dec 5. [Epub ahead of print]
• Shekitka KM, Sobin LH. Ganglioneuromas of the gastrointestinal tract. Relation to Von Recklinghausen disease and other multiple tumor syndromes. Am J Surg Pathol. 1994 Mar;18(3):250-7.
• Liegl B, Bennett MW, Fletcher CD. Microcystic/reticular schwannoma: a distinct variant with predilection for visceral locations. Am J Surg Pathol. 2008 Jul;32(7):1080-7.