[2064] Beta-Human Chorionic Gonadotropin Expression in Giant Cell Tumors

Margaret E Lawless, Mara H Rendi. University of Washington, Seattle, WA

Background: Giant cell tumors are benign yet locally aggressive neoplasms of bone and tendons with a high incidence of recurrence after surgical resection. Additionally, they have the potential to metastasize to distant sites such as the lung and lymph nodes, and the diagnosis can be difficult to establish histologically in this setting. The beta subunit of human chorionic gonadotropin (hCG) is expressed in benign and malignant syncytiotrophoblasts, several non-gynecological neoplasms, and is commonly used as a serum marker in diagnosis and therapeutic monitoring of the associated gynecological tumors. Furthermore, due to the young age of patients with giant cell tumor of bone, urine beta-hCG is often performed to evaluate for pregnancy during the work-up of a lesion. At our institution, we have observed multiple cases of elevated urine beta-hCG in patients with giant cell tumors, which has led to diagnostic difficulty and in one instance, concern for metastatic choriocarcinoma. The aim of this study is to determine if giant cell tumors of bone express beta-hCG, and if so, at what frequency.
Design: We evaluated 15 cases of giant cell tumors consisting of 11 recurrent neoplasms and 4 metastatic lesions. The neoplasms were analyzed for expression of beta-hCG by immunohistochemistry using the Dako polyclonal rabbit beta-hCG antibody and staining was reviewed independently by 2 pathologists.
Results: 40% of cases (n=6) exhibited staining for beta-hCG. 13% had weak (1+) staining, while 20% demonstrated moderate staining (2+), and 7% had strong staining (3+).
Conclusions: Beta-hCG is frequently expressed by recurrent/metastatic giant cell tumors of bone and may be of diagnostic utility when establishing this diagnosis. In addition, it is also important for clinicians and pathologists to be aware of beta-hCG expression by the neoplasm and the potential for elevated urine and serum beta-hCG levels in patients with giant cell tumor of bone so as to avoid misdiagnosis of pregnancy or gestational trophoblastic disease. Currently, the clinical and prognostic significance of beta-hCG expression by giant cell tumors as well as expression by primary tumors is unclear and further studies will address these questions.
Category: Techniques

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 31, Tuesday Afternoon


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