Pathology Outlines

CD Markers
CD99

Author: Nat Pernick, M.D.

Topic Completed: 1 February 2002

Minor changes: 4 January 2021

Copyright: 2002-2021, PathologyOutlines.com, Inc.

PubMed Search: CD99 [title]

Page views in 2020: 23,674

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Table of Contents

Cite this page: Pernick N. CD99. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cdmarkerscd99.html. Accessed January 22nd, 2021.

Definition / general

Also called MIC2, O13, T cell surface glycoprotein E2
Encoded by pseudoautosomal gene on short arms of X and Y
Part of Xg blood group system (NCBI)
Functions: cell surface glycoprotein involved with
1. Differentiation of primitive neuroectodermal cells (Exp Mol Med 2003;35:438)
2. Apoptosis of T cells (FEBS Lett 2003;554:478)
3. T cell adhesion
4. Migration of leukocytes
5. In Ewing / PNET, may promote growth and migration of tumor cells via downregulation of KCMF1 (potassium channel modulatory factor), a possible metastasis suppressor gene (Oncogene 2006;25:2795)
Associated with EWS-FLI1 fusion transcript, t(11;22)(q24;q12), causing FLI-1 protein overexpression

Interpretation

Distinct membranous staining for Ewing / PNET; cytoplasmic for other tumors

Uses by pathologists

Relatively nonspecific marker for Ewing sarcoma and T cell lymphoma, but does distinguish Ewing from neuroblastoma (Hum Pathol 1993;24:880)
Also distinguishes meningeal hemangiopericytoma (CD99+) from anaplastic meningiomas (CD99 weak / focal / negative, Hum Pathol 2004;35:1413)
Detect minimal residual disease by CD99+ flow cytometry in TALL (Leukemia 2004;18:703)
Anti-CD99 antibody may have therapeutic value (Eur J Cancer 2006;42:91)

Microscopic (histologic) images

Images hosted on other servers:

Histologic and
immunohistochemical
features of Ewing's
sarcoma/pPNET

Positive staining - normal

Endothelial cells, ependymal cells, hepatocytes, gastric foveolar epithelium, immature (cortical) thymic lymphocytes (Am J Surg Pathol 1995;19:1115), ovarian granulosa cells, pancreatic islet cells, Sertoli cells, T cells and activated B cells (J Korean Med Sci 1999;14:600)

Positive staining - disease

Ewing sarcoma / PNET:
- 100% (Am J Surg Pathol 2005;29:1025); membranous staining (Mod Pathol 2006;19:659), including tumors of kidney (Am J Surg Pathol 2002;26:320), pancreas (Am J Surg Pathol 2002;26:1040), skin (Am J Surg Pathol 1998;22:310), vulva/vagina (Int J Gynecol Path 2000;19:103); initial report (Am J Surg Pathol 1994;18:486)
Leukemia / lymphoma:
- Acute lymphoblastic lymphoma (B and T, Am J Clin Pathol 2001;115:11, J Korean Med Sci 2005;20:952), anaplastic large cell lymphoma (50%), other lymphomas (occasionally), acute myelogenous leukemia/chloroma (50%, Arch Pathol Lab Med 2006;130:153, Mod Pathol 2000;13:452), leukemia cutis (Mod Pathol 1997;10:283)
Other:
- Adamantinoma of ulna (Clin Orthop Relat Res 2003;408:256)
- Angiomatoid MFH (Hum Pathol 1999;30:1336)
- Atypical fibroxanthoma (73%, Am J Clin Pathol 2002;117:126)
- Breast metaplastic carcinoma (Histopathology 2001;39:578)
- Calcifying aponeurotic fibroma (Hum Pathol 1998;29:1504)
- Cervicovaginal myofibroblastoma (Pathology 2005;37:144)
- Desmoplastic small round cell tumor (23%, Am J Surg Pathol 2002;26:823)
- Ectopic hamartomatous thymoma (Arch Pathol Lab Med 2003;127:e378)
- Endometrial stromal tumors with sex cord differentiation
- Ependymoma (diffuse, strong membranous staining with intracytoplasmic dots, Appl Immunohistochem Mol Morphol 2001;9:125)
- Epithelioid sarcoma (proximal type - 25%, Mod Pathol 2001;14:655)
- Extrarenal malignant rhabdoid tumor
- Gastric carcinoma, intestinal type (some, J Korean Med Sci 2002;17:483)
- Gastrointestinal stromal tumor (Arch Pathol Lab Med 2002;126:1189)
- Giant cell angiofibroma (Am J Surg Pathol 2000;24:971)
- Hemangiopericytoma (meningeal, lipomatous, Hum Pathol 2000;31:1108)
- Hepatocellular carcinoma (Indian J Path Microbiol 2003;46:625)
- Malignant fibrous histiocytoma (35%, J Cutan Pathol 2006;33:24)
- Melanoma (60%, J Cutan Pathol 2006;33:663)
- Merkel cell carcinoma of skin (crisp membranous staining, Appl Immunohistochem Mol Morphol 2000;8:37)
- Mesenchymal chondrosarcoma (Hum Pathol 1996;27:1273)
- Neuroendocrine tumors (Virchows Arch 2000;437:270)
- Nuchal fibromas
- Ovarian sex cord stromal tumors (most, Am J Surg Pathol 2005;29:143, Arch Pathol Lab Med 2000;124:563)
- Ovarian surface epithelial tumors, carcinoids and Wolffian tumors (various)
- Pancreatic endocrine neoplasms (50%, Histopathology 2004;45:384)
- Perineuroma (myxoid sclerosing type)
- Pleomorphic hyalinizing angiectatic tumor (focal, Path Int 2002;52:664)
- Pulmonary pleomorphic (sarcomatoid) carcinoma (J Korean Med Sci 2005;20:50)
- Retinoblastoma (focal in 30%, Ann Diagn Path 2001;5:148)
- Rhabdomyosarcoma (15 - 25%, Oral Oncol 2002;38:450; Am J Surg Pathol 2002;26:1175)
- Sclerosing perineuroma (60%, Am J Surg Pathol 1997;21:1433)
- Sinonasal undifferentiated carcinoma (14%, Am J Surg Pathol 2001;25:156)
- Skin solitary sclerotic fibroma (J Cutan Path 2003;30:631)
- Solitary fibrous tumor: myxoid, Mod Pathol 1999;12:463, oral soft tissue, Am J Surg Pathol 2001;25:900, thyroid gland, Am J Surg Pathol 2001;25:1424, atypical / malignant tumors - 60%, Am J Surg Pathol 1998;22:1501
- Spindle cell epithelioma of vagina (Arch Pathol Lab Med 2001;125:547)
- Superficial acral fibromyxoma (Hum Pathol 2001;32:704)
- Synovial sarcoma (90 - 100%, all types, Am J Surg Pathol 2002;26:1434)
- Testicular sex cord stromal tumors (variable, Hum Pathol 2000;31:1055)
- Uterine tumors resembling ovarian sex cord tumors (57%, Am J Surg Pathol 2002;26:403)
- Wilm tumors (some)

Negative staining

Clear cell sarcoma, myelodysplastic syndrome, neuroblastoma (children, Am J Surg Pathol 1998;22:327, adults, Am J Surg Pathol 2001;25:918; olfactory, Am J Surg Pathol 1998;22:391, Hum Pathol 1995;26:639), small cell carcinoma, smooth muscle tumors, squamous cell carcinoma of skin, thymic carcinoma (Am J Surg Pathol 1997;21:936), Wilm tumor

Additional references

Am J Surg Pathol 2002;26:1040 (PNET - pancreas), Mod Pathol 2002;15:673 (PNET - dura), OMIM 313470