Significance of extensive Mongolian spots in Hunter's syndrome.

BACKGROUND: The importance of early diagnosis in infants with a mild form of Hunter's syndrome should be emphasized. If applied sufficiently early, haematopoietic stem cell transplantation (HSCT) or recombinant enzyme therapy may improve the prognosis. At present, however, diagnosis of the mild form of Hunter's syndrome tends to be delayed, especially in infants with relatively normal intelligence.

OBJECTIVES: To investigate the occurrence of Mongolian spots in infants with Hunter's syndrome, and to clarify the relationship between the Mongolian spots and Hunter's syndrome clinically and histopathologically.

METHODS: Seven Japanese boys with Hunter's syndrome who had received HSCT at ages 4-11 years were observed. The cutaneous manifestations of Mongolian spots before HSCT were evaluated, and compared with those after HSCT. In two patients, the hyperpigmentation from the Mongolian spots was examined by light and electron microscopy.

RESULTS: Pre-HSCT observation revealed that all the patients had an extensive Mongolian spot. These were present at birth and have shown no signs of resolution during the post-HSCT period. Electron microscopic findings showed that pigment-bearing dermal melanocytes contained many free melanosomes in stage IV. These were surrounded by extracellular sheaths and encircled by elastic fibres.

CONCLUSIONS: Our results indicate a strong clinical correlation between the extensive Mongolian spots and Hunter's syndrome. Ultrastructural findings also clearly suggest that the hyperpigmentation is a long-lasting symptom. The recognition of the extensive Mongolian spots is essential as it may lead to early diagnosis in patients with a mild form of Hunter's syndrome.