Inflammatory fibroid polyp: an immunohistochemical study.
BACKGROUND
Inflammatory fibroid polyp is a localized lesion, which arises in the submucosa of the gastrointestinal tract, most often in the stomach. Although it is generally believed to represent a reactive, nonneoplastic condition, its histogenesis remains controversial.


OBJECTIVE
To study inflammatory fibroid polyp by immunohistochemistry in an attempt to further clarify their histogenesis.


METHODS
Nine cases were studied by immunohistochemistry using a panel of antibodies against smooth-muscle actin, vimentin, S-100 protein, factor VIII- R.Ag and macrophage (HAM-56).


RESULTS
There was a strong diffuse positive staining pattern in the spindle cells with vimentin antibody. A patchy staining for smooth-muscle actin was observed in these cells. Immunophenotyping revealed a heterogeneous reaction with HAM-56. In edematous areas, HAM-56-positive cells show voluminous cytoplasm and reniform nuclei. In cell-rich areas, the HAM-56-positive cells had fusiform cytoplasm. Stains for S-100 and factor VIII RAg were negative in the proliferating elements.


CONCLUSIONS
The present immunohistochemical study refutes the suggested neural or vascular nature of the lesion. The strong positivity for vimentin in all cases suggests a major component of spindle cells best recognizable as fibroblasts. These results would favor the existence of a span of morphological and immunohistochemical patterns possibly indicating evolutive phases of an inflammatory reaction.
Santos
Gilda da Cunha
Gda C
Department of Pathology, School of Medicine, Federal University of São Paulo, Ribeirão Preto, SP, Brazil. gildacunha@uol.com.br
Alves
Venâncio A F
VA
Wakamatsu
Alda
A
Zucoloto
Sérgio
S
D000328:Adult; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000737:chemistry / Q000473:pathology; D007417:Intestinal Polyps / Q000737:chemistry / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D014746:Vimentin / Q000032:analysis
D014746:Vimentin