Skip to main content

Thomas J. Hornyak, MD, PhD

Academic Title:

Associate Professor

Primary Appointment:


Secondary Appointment(s):

BioChemistry&Molecular Biology


419 West Redwood Street, Suite 235

Phone (Primary):


Education and Training

  • Princeton University, A.B., Music, 1985
  • The University of Michigan, M.D., Ph.D., Medicine, Biological Chemistry, 1992
  • The New York Hospital-Cornell University Medical Center, Medicine, Internshi,  1993
  • New York University Medical Center, Dermatology, Residency, 1996
  • New York University Medical Center, Post-doctoral fellowship, 1998


Dr. Thomas Hornyak is an internationally recognized physician scientist in pigment cell biology, melanoma and skin cancer. His current position titles are Chair, Department of Dermatology, VA Maryland Health Care System; Associate Professor of Dermatology and Biochemistry and Molecular Biology, University of Maryland School of Medicine;and  Associate Chief of Staff for Research & Development, VA Maryland Health Care System.

FolIowing completion of a Ph.D. in Biological Chemistry emphasizing enzymology and medical training, Dr. Hornyak completed a residency in clinical dermatology and began research on melanocytes as a post-doctoral fellow at New York University. At NYU, Dr. Hornyak described both the transcriptional biochemistry and the developmental determinants of early melanocyte development in the embryo. He completed this work as an independent investigator at the Henry Ford Health System in Detroit. 

Dr. Hornyak extended his work in developmental pigment cell biology to melanocyte stem cells and melanoma epigenetics in the Dermatology Branch of the National Cancer Institute, where he developed a transgenic mouse system to isolate and characterize melanocyte stem cells. At the National Cancer Institute, he developed a clinical protocol utilizing digital dermatoscopy to image selected melanocytic nevi on melanoma-prone patients in a serial manner, using clinical samples of nevi and melanoma to define the role of the Polycomb protein and histone methyltransferase EZH2 in suppressing senescence in melanoma cells.

Research/Clinical Keywords

Melanocyte stem cell differentiation and fate determination as well as melanoma epigenetics

Highlighted Publications

Hornyak, T. J., Bishop, P. D., & Shafer, J. A. "a-Thrombin-Catalyzed Activation of Human Platelet Factor XIII: Relationship between Proteolysis and Factor XIIIa Activity"  (1989) Biochemistry 28, 7326-7332.

Hornyak, T. J., & Shafer, J. A. "Role of Calcium Ion in the Generation of Factor XIII Activity" (1991) Biochemistry 30, 6175-6182.

Hornyak, T. J., & Shafer, J. A. "Interactions of Factor XIII with Fibrin as Substrate and Cofactor"  (1992) Biochemistry 31,  423-429.

Hornyak, T.J., Hayes, D. H., & Ziff, E.B. "Cell Density-Dependent Regulation of Expression and Glycosylation of Dopachrome Tautomerase/Tyrosinase-Related Protein-2 (TRP-2)" (2000)  Journal of Investigative Dermatology 115, 106-112.

Hornyak, T.J., Hayes, D.H., Chiu, L.-Y., & Ziff, E.B. "Transcription Factors in Melanocyte Development: Distinct Roles for Pax-3 and Mitf". (2001) Mechanisms of Development 101, 41-53.

Additional Publication Citations

Potterf, S.B., Mollaaghababa, R., Hou, L., Southard-Smith, E.M., Hornyak, T.J., Arnheiter, H., Pavan, W.J. “Analysis of SOX10 function in neural crest-derived melanocyte development: SOX10-dependent transcriptional control of dopachrome tautomerase”. (2001) Developmental Biology 237, 245-257.

Mahmood, M.N., Lee, M.W., Linden, M.D., Nathanson, S.D., Hornyak, T.J., & Zarbo, R.J. “Diagnostic Value of HMB-45 and Anti-Melan A Staining of Sentinel Lymph Nodes with Isolated Positive Cells”. (2002) Modern Pathology 15, 1288-1293.

Jiao, Z., Mollaaghababa, R., Pavan, W.J., Antonellis, A., Green, E.D., & Hornyak, T.J. “Direct Interaction of Sox10 with the Promoter of Murine Dopachrome tautomerase (Dct) and Synergistic Activation of Dct Expression with Mitf”. (2004) Pigment Cell Research 17, 352-362.

Lanning, J.L., Wallace, J.S., Zhang, D., Diwakar, G., Jiao, Z., & Hornyak, T.J. “Altered Melanocyte Differentiation and RPE Transdifferentiation Induced by Mash1 Expression in Pigment Cell Precursors”. (2005) Journal of Investigative Dermatology 125, 805-17

Jiao, Z., Zhang, Z.G., Hornyak, T.J., Hozeska, A., Zhang, R.L., Wang, Y., Wang, L., Strickland, F.M., & Chopp, M. "Dopachrome tautomerase (Dct) regulated neural progenitor cell proliferation". (2006) Developmental Biology 296, 396-408.

Diwakar, G., Zhang, D., & Hornyak, T.J. “Neurofibromin as a Regulator of Melanocyte Development and Differentiation”. (2008) Journal of Cell Science 121, 167-77.

Kong, H.H., Sibaud, V., Turner, M.L., Fojo, T., Hornyak, T.J., & Chevreau, C. “Sorafenib-Induced Eruptive Melanocytic Lesions”. (2008) Archives of Dermatology 144(6):820-822.

Mahindra, P., DiGiovanna, J.J., Tamura, D., Brahim, J.S., Hornyak, T.J., Stern, J., Lee, C.-C. R., Khan, S.G., Brooks, B.P., Smith, J.A., Driscoll, B.P., Montemarano, A.D., Sugarman, K., &  Kraemer, K.H. “Skin cancers, blindness and anterior tongue mass in African brothers”. (2008) Journal of the American Academy of Dermatology 59 (5),881-886.

Hornyak, T.J., Jiang, S., Guzmán, E.A., Scissors, B.N., Tuchinda, C., He, H., Neville, J.D., & Strickland, F.M. "Mitf Dosage as a Primary Determinant of Melanocyte Survival after UV Irradiation". (2009) Pigment Cell and Melanoma Research 22, 307-318.

Wang, Y., DiGiovanna, J.J., Stern, J.B., Hornyak, T.J., Raffeld, M., Khan, S.G., Oh, K.-S.,  Hollander, M.C., Dennis, P.A., and Kraemer, K.H. “Evidence Of Ultraviolet Type Mutations In Xeroderma Pigmentosum Melanomas”. (2009) Proc. Natl. Acad. Sci U.S.A. 106, 6279-6284.

Chen, D., Lin, Q., Box, N., Roop, D., Ishii, S., Matsuzaki, K., Fan, T., Hornyak, T.J., Reed, J.A., Stavnezer, E., Timchenko, N.A., and Medrano, E.E., “SKI knockdown inhibits human melanoma tumor growth in vivo”. (2009) Pigment Cell and Melanoma Research 22, 761-772.

Zaidi, M.R., Davis, S., Noonan, F.P., Cherry-Graff, C., Hawley, T., Walker, R.L., Feigenbaum, L., Fuchs, E., Lyakh, L., Young, H.A., Hornyak, T.J., Arnheiter, H., Trinchieri, G., Meltzer, P.S., De Fabo, E.C., & Merlino, G. “Interferon-g links ultraviolet radiation to melanomagenesis in mice”. (2011) Nature 469, 548-553.

Fan, T., Jiang, S., Chung, N., Alikhan, A., Ni, C., Lee, C.-C. R., & Hornyak, T.J., “EZH2-Dependent Suppression of a Cellular Senescence Phenotype in Melanoma Cells by Inhibition of p21/CDKN1A expression”. (2011) Molecular Cancer Research 9(4), 418-429.

Zaidi, M.R., Hornyak, T.J., & Merlino, G. “A genetically engineered mouse model with inducible GFP expression in melanocytes”. (2011) Pigment Cell and Melanoma Research 24(2), 393-394.

Ni, C., Zhang, D., Beyer, L.A., Halsey, K.E., Raphael, Y., Dolan, D.F., & Hornyak, T.J. “Hearing Dysfunction in Heterozygous MitfMi-wh/+ Mice, a Model for Waardenburg Syndrome Type 2 and Tietz Syndrome”. (2013) Pigment Cell & Melanoma Research 26(1), 78-87.

Saha, K., Hornyak, T.J., Eckert, R.L. “Epigenetic cancer prevention mechanisms in skin cancer”. (2013) AAPS J. 15, 1064-1071.

Adhikary, G., Grun, D., Kerr, C., Balasubramanian, S., Rorke, E.A., Vemuri, M., Boucher, S., Bickenbach, J.R., Hornyak, T., Xu, W., Fisher, M.L., Eckert, R.L. “Identification of a Population of Epidermal Squamous Cell Carcinoma Cells with Enhanced Potential for Tumor Formation” (2013) PLoS One.

Masaki, T., Wang, Y., Digiovanna, J.J., Khan, S.G., Raffeld, M., Beltaifa, S., Hornyak, T.J., Darling, T.N., Lee, C.C., Kraemer, K.H. “High frequency of PTEN mutations in nevi and melanomas from xeroderma pigmentosum patients” (2014)  Pigment Cell & Melanoma Research 27(3), 454-464. PMID: 24483290.

Huang, J.M. & Hornyak, T.J. “Polycomb Group Proteins – Epigenetic Repressors with Emerging Roles in Melanocytes and Melanoma” (2015) Pigment Cell and Melanoma Research, 28, 330-339. PMID: 25475071

Jiang, S., Joshi, S.S., Kalapurakal, E., Fan, T., & Hornyak, T.J. “Inhibition of Vemurafenib-associated MAP Kinase activation and induction of melanization in BRAFWT melanoma cells by 17-AAG” (2016) Under revision for PLoS One.

Joshi, S.S., Castaneda, M., Jiang, S., Diwakar, G., Hertzano, R.P., & Hornyak, T.J. “Characterization of a new, inducible transgenic mouse model with GFP expression in melanocytes and their precursors” (2017) Submitted to Gene Expression Patterns.

Non-Peer Reviewed Publications and Commentaries

Hornyak, T.J. “The Clinician-Researcher’s Unique Perspective” (1990) JAMA (Pulse Student Supplement) 263, 756.

Udey, M.C. & Hornyak, T.J. “In this issue—oncogenes, tumor suppressor genes and melanocytic lesions” (2004) Journal of Investigative Dermatology 122, VII-VIII.

Diwakar, G. & Hornyak, T.J. "Café-au-lait Patches and Senile Plaques: How APPt the Connection?" (2006) Journal of Investigative Dermatology 126, 547-550.

Huang, J., Chikeka, I., & Hornyak, T.J. “Melanocytic Nevi and the Genetic and Epigenetic Control of Oncogene-Induced Senescence” (2017) Dermatologic Clinics 35, 85-93.

Book Chapters

Boissy, R.E. & Hornyak, T.J., "Extracutaneous Melanocytes", in The Pigmentary System, Second Edition (Blackwell Publishing, 2006).

Hornyak, T.J. "The Developmental Biology of Melanocytes, and Its Application to Understanding Human Congenital Disorders of Pigmentation", in Advances in Dermatology, 22:201-18. (Elsevier, 2006).

Hornyak, T.J. “Albinism and Other Genetic Disorders of Pigmentation”, Chapter 71 of Dermatology in General Medicine, Seventh Edition (McGraw-Hill, 2007).

Hornyak, T.J., Chung, N., and Tachibana, M. "MITF and the Waardenburg Type II and
Albinism-Deafness (Tietz) Syndromes", Chapter 71 of Inborn Errors of Development, Second Edition (Oxford, 2008).

Hornyak, T.J. “Future Advances in Melanoma Research”, in Clinics in Plastic Surgery 37 (2010), 169-176.

Hornyak, T.J. “Albinism and Other Genetic Disorders of Pigmentation”, Dermatology in General Medicine, Eighth Edition (McGraw-Hill, February 2012)

Morganroth, P. & Hornyak, T.J. “Oculocutaneous Albinism”, Chapter 49 in Skin of Color, Second Edition (McGraw-Hill, March 2016).

Naga, L. & Hornyak, T.J. "MITF and the Waardenburg Type II and Albinism-Deafness (Tietz) Syndromes", Inborn Errors of Development, Third Edition (Oxford, 2016).

Awards and Affiliations

  • Outstanding Teacher Award, University of Maryland Department of Dermatology, May 2016
  • Excellence Award in Melanoma Research – Poster Presentation, Society for Melanoma Research Congress, November 2009
  • Pigment Cell Research Outstanding Article, 2004
  • Edward A. Krull Annual Faculty Role Model Award, Department of Dermatology, Henry Ford Health System, June 2001
  • Fund for Henry Ford Hospital New Investigator Award, January 1999
  • Young Investigator Award, American Academy of  Dermatology, 1998
  • Travel Award, Pan-American Society for Pigment Cell Research, June 1997
  • Albert M. Kligman Travel Fellowship, Society of Investigative Dermatology, April 1997
  • Research Award for Clinical Trainees, NIH Office of  Education,  September 1993
  • George R. Demuth Medical Scientist Training Award, The University of Michigan, 1992
  • Life & Health Insurance Medical Research Fund M.D./Ph.D. Fellowship, 1988-1992
  • Medical Scientist Training Program M.D./Ph.D. Fellowship, The University of Michigan, 1985-1988
  • Helen and Isidore Sacks Memorial Recital, Princeton University, January 1987
  • Phi Beta Kappa, Princeton University, 1985
  • Helen and Isidore Sacks Memorial Prize in Musical Performance, Princeton University, 1985
  • Performance, Princeton University,
  • National Merit Scholar, 1981-1985

Professional Activity

Professional Societies

  • Society for Investigative Dermatology
  • Pan-American Society for Pigment Cell Research
  • American Academy of Dermatology