Do ultrastructural findings in progressive macular hypomelanosis indicate decreased melanin production?
Hypopigmentation in PMH seems to be the result of an altered melanogenesis based on a decrease in melanin formation and a change in the distribution of melanosomes. In lesional skin of PMH patients with skin type V and VI less melanized, aggregated melanosomes in stead of single, mature melanosomes are transferred from melanocytes to keratinocytes. This results in a decrease of epidermal melanin. Further investigations are needed to determine the precise role of Propionibacterium acnes in this alteration of melanogenesis.
These observations show that laparoscopic resection techniques in this canine model resulted in a more rapid return to normal gastrointestinal transit compared with open colectomy.