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Meet the Team

Our growing team of specialists treats patients all over Long Island. Our professionals provide expert care you can trust. We are happy to be a key part of your care team.


Dr. Silverstein grew up right here on Long Island in Suffolk County and attended Stony Brook University where he completed his undergraduate degree and his residency training in dermatology. During medical school, he graduated at the top of his class and was selected to the prestigious medical honor society, Alpha Omega Alpha, as a junior member, one of only 3 people to be selected out of 125 in his class. During his residency training, he served as Chief Resident. He scored at the top percentile on his board certifying exam.  He is currently a Clinical Assistant Professor of Dermatology at Stony Brook where he sees patients during half the week and is the Director of the Inpatient Consultative Service and thus provides care to the most complicated dermatology patients on Long Island.  Additionally, he actively teaches dermatology residents and is the Director of the Clinical Clerkship in Dermatology for School of Medicine.  Dr. Silverstein has published multiple articles and continues to do so in major dermatology journals, having authored more than a half dozen manuscripts in the last 2 years.

In addition to these roles, prior to founding IslandWide Dermatology, Dr. Silverstein saw patients privately in Port Jefferson and Patchogue.  Dr. Silverstein is honored to now provide care right here in Ronkonkoma and Riverhead. His philosophy is that he treats every patient as a family member and only provides the highest quality, ethical medicine. He believes in a patient-centered approach and wants every patient to feel comfortable with their care.

Dr. Silverstein provides care in all aspects of dermatology including common dermatologic ailments, complex medical dermatology, surgical dermatology, and cosmetic dermatology.


Dr. David Silverstein


Alexa Haemer - PA

Alexa Haemer is a Board Certified Physician Assistant specializing in medical, surgical and cosmetic dermatology, practicing in our Ronkonkoma and Riverhead locations. Prior to joining Islandwide, Alexa spent several years working in the dermatology field having multiple roles including administrative as well as clinical.

Alexa graduated from Stony Brook University in Stony Brook, New York with a bachelor’s degree with a major in Health Science before receiving her master’s degree from the Touro College Physician Assistant program. During her clinical training, Alexa studied the adverse effects of isotretinoin, a common medication used in the dermatology field for severe, nodulocystic acne. Alexa graduated from Touro College Magna Cum Laude and top in her class, receiving both the Outstanding Academic Achievement Award and Outstanding Clinical Achievement Award. She is a member of the Pi Alpha National Honor Society for Physician Assistants. In addition, Alexa is an active member of the American Academy of Physician Assistants, the New York State Society of Physician Assistants and the Society of Dermatology for Physician Assistants.

Ms. Haemer’s primary focus and dedication is to improve and maintain the health and beauty of her patients’ skin as well prevent and minimize the risks of skin cancer and photo-aging. She is skilled in the diagnosis as well as treatment in all medical dermatology, including but not limited to, acne, eczema, psoriasis, hair loss and hyperhidrosis. Alexa is experienced in multiple cosmetic treatments and procedures such as the use of neuromodulators and dermal fillers. She combines her dermatological skills to achieve skin health and restore a natural look of beauty in an individualized manner for every patient. Patient care along with comprehensive dermatological diagnostics remain at the forefront for Alexa as she continues her career at Islandwide Dermatology.

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Mariah Messina - PA

Mariah Messina is a physician assistant who was born and raised in Suffolk County, New York. She attended Loyola University Maryland where she completed her bachelor’s degree in biology and mathematics. She then attended the Touro College of Health Sciences where she earned a Master in Physician Assistant Studies degree. She is currently board-certified by the National Commission on Certification of Physician Assistants and is an active member of the AAPA and NYSSPA. 

Prior to becoming a physician assistant, Mariah worked in a general and vascular surgical practice where she gained experience and interest in in-office surgical procedures. After earning her master’s degree, she then started her career as a PA in endocrinology, with a strong focus in metabolic diseases. This provided Mariah with a great foundation in caring for patients with hormone imbalances and understanding the importance of patient education. With that, she quickly learned that many dermatological symptoms stem from underlying conditions including thyroid disorders, diabetes mellitus, obesity, and testosterone and estrogen imbalances.

Mariah has always had a true passion for dermatology and is pleased to be incorporating her background in endocrinology and surgery into her work here at IslandWide Dermatology. She practices in both our Ronkonkoma and Riverhead offices where she cares for patients of all ages in medical and cosmetic dermatology, as well as surgical procedures. 

Mariah believes in building a strong patient rapport for patients to feel comfortable, supported, and understood. Her goal is to thoroughly educate her patients to understand their conditions and treatment options. She strives for patients to feel confident to ask questions, share their concerns, and trust that their individualized health conditions are being cared for. 

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