CD56 Expression in Bone and Osteoblastic Neoplasia: A Novel Osteoblast Marker?

D.E. Hughes, R. Deb, D.C.Mangham, V.P. Sumathi and R.J. Grimer Royal Orthopaedic Hospital, Birmingham, U.K.

1

CD56/NCAM

 Cell adhesion molecule of the immunoglobulin superfamily  Involved in homotypic cell-cell interactions  Possible role in neural morphogenesis  Restricted tissue distribution

2

CD56 expression in normal tissues  Neurons, gangliocytes  Plasma cells  Natural killer cells

3

CD56 expression in tumours

 Myeloma  Neuroendocrine carcinomas  Neuroblastoma  Phaeochromocytoma  Some glial tumours  NK-type LGL

4

Previous evidence of CD56 expression in osteoblast lineage  Expressed by calvarial cells in vitro  Described in association with CD56 expression in myeloma in osteoblasts  Reported in osteosarcomas  Not expressed in Ewing’s sarcoma  Not expressed in chondrosarcoma

5

Aim of study

 To assess CD56 expression in normal cells of the osteoblast lineage  To assess CD56 expression in tumour-like lesions in which bone is formed  To assess CD56 expression in osteoblastic neoplasms

6

Methods

 Cases selected from Royal Orthopaedic Hospital paraffin archive to represent a broad range of normal bone, reactive conditions, tumour-like conditions and osteoblastic tumours  CD56 expression assessed by a standard immunohistochemical approach

7

Immunohistochemistry

 Novacastra anti CD56 clone 1B6 at 1:50  High temperature antigen retrieval in citrate/EDTA  Detection by Enivision system

Appendix CD56 staining of neural cells 8

Case selection – benign

 Normal/reactive bone (31 cases)  Quiescent bone  Callus, periosteal reaction  Benign bone tumours and tumour-like conditions (24 cases)  Aneurysmal bone cyst        Fibrous dysplasia Osteofibrous dysplasia Non-ossifying fibroma Desmoplastic fibroma Osteoid osteoma Osteoblastoma Giant cell tumour

9

Case selection – malignant

 Malignant osteogenic tumours (23 cases)  High grade intramedullary osteosarcoma  Telangiectatic osteosarcoma  Intermediate grade chondroblastic osteosarcoma  Parosteal osteosarcoma  Low grade central osteosarcoma  Undifferentiated recurrences of known osteosarcomas  Non bone-forming intra-osseous sarcomas

10

Results: normal bone (1)

Strong expression in lining cells and osteoblasts 11

Results: normal bone (2)

Weak expression in stromal cells adjacent to osteoblast seams Osteocytes Predominantly negative 12

Results: callus

No expression in cartilage No expression in fibroblasts Strong expression in osteoblasts 13

Results: periosteal reaction

No expression in outer fibrous layer Strong expression in bone-forming areas 14

Results: aneurysmal bone cyst

Strong expression on Surface layer of septal structures Background stromal Population negative 15

Results: fibrous dysplasia

Spindle cell component positive – most strongly adjacent to areas of bone formation Similar results in osteofibrous dysplasia 16

Results: non-ossifying fibroma

Some expression in spindle cells adjacent to bone Similar results in desmoplastic fibroma 17

Results: osteoid osteoma

Nidus osteoblasts positive Similar results in osteoblastoma 18

Results: giant cell tumour

Focal weak expression by spindle cell component Osteoclasts negative 19

Results: high grade osteosarcoma

Most tumour cells positive Strong expression in osteoblastic areas Loss of expression in chondroblastic areas 20

Results: parosteal osteosarcoma

Variable expression in spindle cell component – stronger adjacent to areas of osteoid Similar results in low grade central osteosarcoma 21

Results: telangiectatic osteosarcoma

Focal expression In undifferentiated Tumour cells 22

Results: undifferentiated recurrence of high grade osteosarcoma

Areas of expression in the absence of osteoid formation Similar results in some undifferentiated intra-osseous sarcomas 23

Results - summary by cell type: non-neoplastic

 Normal osteoblasts – always positive  Normal osteocytes – mostly negative  Normal periosteal spindle cells – positive in areas of active bone formation  Normal bone marrow stromal cells positive in areas of active bone formation

24

Results - summary by cell type: neoplastic  Neoplastic osteoblasts – consistently positive  Neoplastic osteocytes – variably positive  Neoplastic spindle cells with osteogenic potential – variably positive  Neoplastic spindle cells without evidence of osteogenic potential – sometimes positive

25

Conclusions

 CD56 is consistently strongly expressed by normal and neoplastic osteoblasts  CD56 expression also occurs in non osteogenic spindle cells in bone and bone lesions – purposes it may not be a specific marker of osteoblastic potential for diagnostic  CD56 may be a biologically important molecule in osteoblast function

26