Mark Koh, MD, on Pathology, Genetics, and Global Collaboration in Pediatric Dermatology

At the 2026 Society for Pediatric Dermatology (SPD) Annual Meeting, Mark Koh, MD, of KK Women's and Children's Hospital in Singapore, highlighted advances in pediatric histiocytosis and emphasized the growing role of dermatopathology in improving diagnostic accuracy for complex pediatric skin diseases. Koh, who is a pediatric dermatologist, dermatopathologist, secretary of the International Society of Pediatric Dermatology (ISPD), and president of the Asian Society of Pediatric Dermatology (ASPD), also discussed ongoing efforts to expand international collaboration and education within the specialty.

The first part of the Hurwitz Lecture focused on pediatric histiocytosis, providing attendees with an overview of the current classification of these rare disorders. He devoted particular attention to Langerhans cell histiocytosis (LCH), the most common histiocytic disorder encountered in children. The session reviewed the evolving understanding of disease pathogenesis, including the discovery of mutations involving BRAF and other components of the RAS/MAPK signaling pathway that have reshaped understanding of LCH as a molecularly driven disease. Koh also reviewed the clinical manifestations and diagnostic approach to histiocytosis before discussing how these molecular discoveries have translated into targeted treatment strategies, including therapies directed against BRAF and MEK pathway alterations.

In the second session, Koh explored the practical role of dermatopathology in pediatric dermatology, emphasizing that histopathologic evaluation remains an essential complement to clinical assessment. He presented a series of illustrative cases demonstrating situations in which skin biopsy was necessary to confirm a suspected diagnosis, exclude competing diagnoses, or resolve discrepancies between clinical findings and pathology. In some cases, unexpected biopsy results prompted clinicians to reevaluate patients clinically before arriving at the correct diagnosis, highlighting the importance of close clinicopathologic correlation.

Koh also discussed the expanding diagnostic utility of biopsy specimens for genetic testing, noting that tissue samples increasingly provide valuable molecular information that can guide diagnosis and management. In addition, he reviewed the use of hair mount examinations as a simple but effective diagnostic tool for common pediatric hair disorders, including telogen effluvium, alopecia areata, and trichotillomania.

Beyond his talks, Koh underscored the importance of international collaboration in pediatric dermatology. As secretary of the ISPD and president of the ASPD, he described ongoing efforts to expand membership and strengthen educational outreach, particularly by encouraging greater participation from pediatric dermatologists in North America, Europe, and Asia. Both organizations offer free membership and provide educational resources designed to support clinicians worldwide while improving care in underserved regions.

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