[30] Oncofetal Protein IMP3: A Specific Biomarker That Distinguishes Leiomyoma from Leiomyosarcoma.

Kristine Cornejo, Min Shi, Zhong Jiang. UMass Memorial Medical Center and University of Massachusetts Medical School, Worcester

Background: The diagnosis of leiomyosarcoma can be very difficult when distinguishing these lesions from variants of leiomyoma. IMP3, an oncofetal protein plays an important role in embryogenesis and carcinogenesis of certain malignant neoplasms. Several studies have shown that IMP3 is a cancer specific biomarker. The aim of this study was to investigate the expression of IMP3 in leiomyoma and leiomyosarcoma and to determine whether IMP3 can serve as a diagnostic biomarker for leiomyosarcoma.
Design: A total of 146 cases (resection, n= 118; biopsy, n=28) obtained from the surgical pathology files of a tertiary Medical Center consisting of 62 leiomyomas (uterine, n=59; soft tissue, n=2) and 84 leiomyosarcomas (uterine, n=15; soft tissue, n=69) were examined by immunohistochemistry for IMP3 expression. Among the leiomyosarcoma cases, 54 were primary, and 30 were metastatic. All cases were collected between January 1997 and December 2009, and the diagnosis was confirmed by at least two pathologists.
Results: A positive immunohistochemical stain for IMP3 (cytoplasmic staining) was not identified in any of the 62 leiomyoma cases (0%) and was significantly increased (p<0.0001) in leiomyosarcoma highlighting 43 of 84 cases (51%). Of the 84 leiomyosarcoma cases, 54 were primary and 30 were metastatic with IMP3 staining in 50% and 53% of cases, respectively. IMP3 positivity was detected in >50% of tumor cells in 19 (23%) cases, 26-50% of tumor cells in 9 (11%) cases and <25% of tumor cells in 15 (18%) cases. IMP3 expression was detected in 23 of 44 (52%) intermediate and high-grade (nuclear grade II-III/III) and 4 of 7 (57%) low-grade leiomyosarcomas (nuclear grade I/III). Positive IMP3 staining was detected within 7 of the 15 (47%) cases of uterine and 36 of the 69 (52%) cases of soft tissue leiomyosarcomas. The sensitivity of IMP3 for the detection of leiomyosarcoma was 51% and the specificity was 100%.
Conclusions: The high degree of specificity of IMP3 for leiomyosarcoma suggests it can be used as a diagnostic biomarker. The expression of IMP3 in tumor cells can increase the level of confidence in establishing a definitive malignant diagnosis in both uterine and soft tissue leiomyosarcomas.
Category: Bone & Soft Tissue

Monday, February 28, 2011 1:00 PM

Poster Session II # 15, Monday Afternoon


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