Microtubule-associated protein-2 is a sensitive marker of primary and metastatic neuroblastoma.
BACKGROUND
Microtubule-associated protein-2 (MAP-2) is a protein expressed in high levels in cells derived from the neural crest. To the best of our knowledge, MAP-2 expression has not been thoroughly evaluated in tissues outside of the central nervous tissue. We examined the diagnostic utility of MAP-2 as a marker of neuroblastoma and attempted to characterize the expression of this protein in other tumors in the morphologic differential diagnosis of neuroblastoma.


RESULTS
MAP-2 showed significant cytoplasmic reactivity in 95% of primary and 100% of metastatic neuroblastomas. Included within this set of tumors were 3 undifferentiated neuroblastomas, all of which showed strong staining. MAP-2 did not show significant staining in the majority of other small round blue cell tumors within the morphologic differential. Additionally, MAP-2 showed comparable sensitivity in staining primary neuroblastomas as compared with synaptophysin, chromogranin, CD56, and beta-catenin. In contrast to other markers of neuroblastoma, MAP-2 did not show significant cross reactivity to native bone marrow precursors, thus eliminating a potential source of confusion. In normal tissues, MAP-2 staining was essentially restricted to organs derived from the neural crest (adrenal medulla, endocrine organs). Variant patterns of staining were seen in exocrine organs, monocyte/macrophages and solitary fibrous tumor/hemangiopericytoma family of tumors. Rarely, high-grade adult sarcomas exhibiting strong cytoplasmic MAP-2 staining were seen.


CONCLUSIONS
MAP-2 is a sensitive and specific marker of neuroblastoma, both in the primary tumor and bone marrow biopsy settings. We think that MAP-2, in conjunction with synaptophysin, is a very powerful immunohistochemical marker in differentiating neuroblastoma from its morphologic mimics.
Krishnan
Chandra
C
Department of Pathology, Stanford University, Stanford, CA 94205, USA. Chandra.krishnan@yahoo.com
Higgins
John P
JP
West
Robert B
RB
Natkunam
Yasodha
Y
Heerema-McKenney
Amy
A
Arber
Daniel A
DA
D014408:Biomarkers, Tumor / Q000378:metabolism*; D019046:Bone Marrow Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000556:secondary; D003593:Cytoplasm / Q000378:metabolism / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009447:Neuroblastoma / Q000175:diagnosis* / Q000378:metabolism / Q000556:secondary; D011237:Predictive Value of Tests; D016708:Synaptophysin / Q000378:metabolism; D046888:Tissue Array Analysis
D014408:Biomarkers, Tumor; C489788:MAP2 protein, human; D008869:Microtubule-Associated Proteins; D016708:Synaptophysin