[68] CD138 Expression in Osteosarcoma.

Amberly L Nunez, Gene P Siegal, Vishnu Reddy, Shi Wei. University of Alabama at Birmingham

Background: CD138 (syndecan-1) is a cell surface proteoglycan that is highly sensitive and specific for plasmacytic differentiation within the spectrum of hematologic disorders. Expression of syndecan-1, recognized by CD138-clustered antibodies, has also been observed in a majority of epithelial neoplasms and, rarely, soft tissue tumors. However, reactivity for CD138 in bone tumors has not been reported.
Design: A total of 27 consecutive cases of osteosarcoma were retrieved over a five-year period (January, 2005 – July, 2010) from the authors' institution. CD138 immunoexpression was examined on cases with tissue available (n=22). Tumors were scored as positive when any unequivocal membranous staining was identified regardless of strength. Those with positive CD138 staining were subsequently stained for immunoglobulin kappa and lambda (IgK and IgL). Similarly, a tissue microarray (TMA), consisting of 24 cases of human osteosarcoma, 24 cases of chondrosarcoma, 12 cases of giant cell tumor of bone and 9 cases of normal bone, was also evaluated.
Results: Twenty-two cases of osteosarcoma derived from 11 men and 11 women, aged 10-77 (mean age of 26.1 years), were evaluated. These included 17 cases of conventional type (13 osteoblastic, 2 chondroblastic, 1 mixed osteoblastic and chondroblastic, and 1 osteoblastic with dedifferentiated leiomyosarcoma), 2 cases of small cell type and 3 cases of parosteal osteosarcoma. Eight cases showed CD138 expression (6 conventional, 1 small cell, 1 parosteal). Two cases of osteosarcoma from the TMA (both osteoblastic) were positive for CD138. All these cases were negative for subsequent IgK and IgL staining. All cases of chondrosarcoma, giant cell tumor of bone and normal bone were negative for CD138. Thus, CD138 expression was seen in 22% of osteosarcoma cases (10/46), but not in other cases examined.
Conclusions: To our knowledge, this is the first study to examine CD138 expression in bone tumors. Our results show that CD138 reactivity for neoplastic cells in bone is not a definitive marker for plasmacytic origin. The expression of CD138 in osteosarcoma may represent a potential diagnostic pitfall, especially in a bone biopsy where the nature of the lesion needs to be determined from a limited amount of tissue. Thus, caution is required to interpret CD138+ cells from a bony lesion for which a hematologic etiology has not been established. Additionally, when plasmacytoma is in the differential diagnosis, IgK and IgL along with other appropriate markers and careful radiological correlation are needed to reach the correct diagnosis.
Category: Bone & Soft Tissue

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 2, Tuesday Morning


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