[68] Giant Cell Lesions of Bone and Soft Tissues: Diagnostic Value of Immunohistochemistry

MD Linden. Henry Ford Hospital, Detroit, MI

Background: Giant cell lesions of bone and soft tissues are a heterogeneous group. This includes both benign and malignant tumors with a broad range of clinical behaviors. Accurate diagnosis is essential for determination of prognosis and guiding treatment decisions. Clinicians are more frequently submitting needle core biopsy and fine needle aspiration specimens of mesenchymal lesions, often providing only limited amounts of lesional tissue for diagnosis. Immunohistochemistry may be a useful ancillary tool to discriminate giant cell tumor of bone from other giant cell rich lesions, especially on specimens with limited cellularity.
Design: A group of giant cell rich lesions of bone and soft tissue were selected from the surgical pathology archives at Henry Ford Hospital. Cases included the following- giant cell tumor of bone (5), giant cell tumor of tendon sheath (20), pigmented villonodular tenosynovitis(10), phosphaturic mesenchymal tumor, mixed connective tissue variant (1), and aneurysmal bone cyst (4). An immunohistochemistry panel was performed consisting of p63, CD 34, CD 68, CD 117, and CD 163. Immunoreactivity of cases was scored as negative, focal positive (<5%), and positive(>5%). Lesional component staining was also recorded as to specific cell population, stromal cells and/or giant cells.
Results: All cases (5/5) of giant cell tumor of bone were immunoreactive with p63. Both stromal cells and giant cells. CD163 showed variable staining of both stromal cells and giant cells. CD68 stained only giant cells. CD34 and CD117 were negative. Similar staining patterns were observed with aneurysmal bone cyst. 4/4 cases were p63 positive. All cases of giant cell tumor of tendon sheath and pigmented villonodular tenosynovitis were p63 negative. In contrast, both CD68 and CD163 showed immunoreactivity of both giant cells and stromal cells. CD34 and CD117 were negative. The one case of phosphaturic mesenchymal tumor was negative with all of the immunostains.
Conclusions: We observed p63 immunostaining only in cases of giant cell tumor of bone and aneurysmal bone cyst, findings similar to previous reports in the literature. CD68 and CD163 staining appeared restricted to giant cell tumor of tendon sheath and pigmented villonodular tenosynovitis. CD34 and CD117 were non-contributory in this series of cases. These patterns of immunoreactivity may be useful to discriminate giant cell tumor of bone (p63 positive) from other giant cell rich lesions of bone and soft tissue such as GCTTS and PVNS (p63 negative), especially on limited samples.
Category: Bone & Soft Tissue

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 25, Tuesday Morning