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  • Surgical Pathology Criteria

    Mucosal Schwann Cell Hamartoma

    Definition

    • Intramucosal infiltrate of S100 positive spindled cells lacking other neural elements

    Diagnostic Criteria

    • Lamina propria expanded by an infiltrate of spindled cells
      • Indistinct borders
      • Surrounds and entraps crypts
    • Uniform bland spindled cells
      • Abundant dense eosinophilic cytoplasm
      • Indistinct cell borders
      • No atypia, pleomorphism or mitotic activity
    • No ganglion cells in lesion
    • Axons very rare to absent
    • Extensively S100 positive
      • Negative for GFAP, claudin1, CD34, CD117, smooth muscle actin
    • All reported cases occur in the colorectum
      • Most are distal
    • 1-6 mm in size
    • No relationship to familial syndromes
    • Benign
      • No recurrence

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

    Original posting : November 29, 2009

    Differential Diagnosis

    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

    GI Schwannoma GI Mucosal Schwann Cell Hamartoma
    Most cases intramural Confined to lamina propria
    Peripheral lymphoid cuff common Lacks lymphoid cuff
    Frequent pleomorphic hyperchromatic cells No pleomorphism
    90% in stomach Restricted to colorectum

    GI Mucosal Schwann Cell Hamartoma GI Neurofibroma
    Axons very rare to absent Axons scattered throughout
    Very uniform infiltrate More heterogeneity in infiltrate
    Restricted to colorectum Most are in stomach and small intestine

    GI Mucosal Schwann Cell Hamartoma GI Perineurioma
    Abundant cytoplasm Scant cytoplasm
    No association with hyperplastic crypts Frequently associated with hyperplastic crypts
    Perineurial markers negative Perineurial markers positive
    S100 positive S100 negative

    GI Mucosal Schwann Cell Hamartoma GI Mucosal Neuroma
    Axons very rare to absent Axons numerous
    Very uniform infiltrate Hyperplastic bundles of nerve fibers
    Restricted to colorectum Very rare in intestines
    No association with syndromes Associated with MEN2b

    Bibliography

    • 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.
    • 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. 2009 May;33(5):781-7.
    Printed from Surgical Pathology Criteria: http://surgpathcriteria.stanford.edu/
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