DOI

10.17077/etd.hhzib69b

Document Type

Thesis

Date of Degree

Spring 2016

Degree Name

MS (Master of Science)

Degree In

Oral Science

First Advisor

Hellstein, John W

First Committee Member

Robinson, Robert A

Second Committee Member

Timmons, Sherry Rene

Third Committee Member

Handoo, Nidhi Q

Abstract

The objective of this study is to use immunohistochemistry to determine whether myofibroma is a distinct entity or a variation of other fibroblastic entities. Staining patterns of vimentin, SMA and CD34 are evaluated in irritation fibromas, ulcerated fibromas, giant cell fibromas, inflammatory fibrous hyperplasias, focal keratosis and chronic mucositis, used in this study as a control group, and myofibromas. This study assesses whether myofibromas demonstrate similar staining patterns of vimentin, SMA and CD34 to the aforementioned lesions and if these stains are adequate in differentiating the entities.

Upon IRB approval, 46 cases of irritation fibroma, 45 cases of ulcerated irritation fibroma, 44 cases of giant cell fibroma, 47 cases of focal keratosis and chronic mucositis, and 23 cases of myofibroma were collected. Hematoxylin and eosin-stained slides were reviewed and immunohistochemistry of vimentin, SMA and CD34 was performed. Staining patterns were graded as 0, 1 and 2 (≤25%; ≤25-50%; and ≥50% respectively). Differences were analyzed by the Kruskal-Wallis exact test and Dunn's test for pairwise comparisons.

Vimentin demonstrated grade 2 positivity in all groups with 6.5% and 4.4% of irritation fibromas and myofibromas demonstrating grade 1 positivity, respectively. Smooth muscle actin was strongly positive in myofibroma (78.3%, grade 2, p < 0.05) but also demonstrated positivity in focal keratosis and chronic mucositis (2.1% grade 1), giant cell fibromas (4.6% grade 1, 4.6% grade 2), inflammatory fibrous hyperplasias (13.6% grade 1, 13.6% grade 2) and ulcerated irritation fibromas (6.7% grade 2, 8.9% grade 1) though this was not statistically significant. CD34 demonstrated statistically significant positivity in irritation fibromas (87% grade 2, 2.2% grade 1), ulcerated irritation fibromas (73.3% grade 2, 6.7% grade 1), and inflammatory fibrous hyperplasias (63.6% grade 2, 6.8% grade 1). CD34 also demonstrated positivity in giant cell fibromas (54.6% grade 2, 2.3% grade 1) and myofibromas (21.7% grade 2, 4.4% grade 1) though this was not statistically significant. The Dunn’s test for pairwise comparisons revealed statistically significant differences for CD34 staining between myofibroma and fibroma; myofibroma and focal keratosis and chronic mucositis; myofibroma and inflammatory fibrous hyperplasia; and between myofibroma and ulcerated fibroma.

The results indicate that smooth muscle actin immunohistochemistry is helpful but not definitive in delineating myofibroma as a separate entity. In addition, as other fibrous proliferations in our study also expressed smooth muscle actin, it is possible that smooth muscle actin expression correlates with the duration and chronic tissue assault associated with a lesion, thus supporting the theory that oral myofibromas are part of the spectrum of fibrous proliferations. The results also indicate that although CD34 is deemed a specific marker for solitary fibrous tumor, this marker was not reliable in distinguishing any of the entities from one another and may in fact not be specific for solitary fibrous tumor. Further studies are needed to support this claim.

Pages

ix, 57 pages

Bibliography

Includes bibliographical references (pages 48-57).

Copyright

Copyright © 2016 Chandni Desai

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