Synopsis

 solitary lesion
 cytologically bland spindled cells with fibroblastic features
 monomorphic spindle cell proliferation in the lamina propria, without necrosis or mitotic activity
 lesions intimately associated with the muscularis mucosae
 wide separation and disorganization of the colonic crypts

Immunohistochemistry

 strong and diffuse positivity for vimentin only
 occasional weak and focal reactivity for CD34
 occasional weak and focal reactivity for smooth muscle actin

Ultrastructure

 fibroblastic differentiation of spindle cells

Differential diagnosis

 other digestive stromal polyps

References

 Eslami-Varzaneh F, Washington K, Robert ME, Kashgarian M, Goldblum JR, Jain D. Benign fibroblastic polyps of the colon: a histologic, immunohistochemical, and ultrastructural study. Am J Surg Pathol. 2004 Mar;28(3):374-8. PMID: #15104300#