Clinical, Pathological, and Etiologic Aspects of Acquired Dermal Melanocytosis

Abstract

To study the pathogenesis of acquired dermal melanocytosis (ADM), we reviewed the clinical, immunohistochemical, and ultrastructural features of 34 cases (female, 33, and male, 1) of ADM. The patients' ages at onset ranged from 8 to 51 years and averaged 26.8 +/- 12.7 years. There was a positive family history. Gray-brown macules were mostly recognized on the face. Not only active dermal melanocytes but also non-pigmented c-KIT- and TRP-2-positive immature melanocytes were detected in the dermis. Taken together those clinical and histological findings, activation of pre-existing immature melanocytes by sunlight, estrogen, and/or progesterone, and some other factors, may be the most likely mode of the development of ADM. Moreover, using cultured murine neural crest cells as a model of c-KIT-positive immature melanocytes, we confirmed that endothelin-1, which is produced and secreted by keratinocytes after UV-irradiation, affects melanocytes and accelerated melanogenesis.

Comparison of acquired bilateral nevus of Ota-like macules in men and women

“…Extra-facial lesions are rare but can occur on the back, limbs, or extremities. [10][11][12][13] It is unclear whether the extra-facial condition is a separate entity from acquired bilateral nevus of Ota-like macules. A previous study found no significant difference in the histopathological features of facial and extra-facial lesions.…”

Melanocyte precursors express elastin binding protein and elastin-derived peptide (VGVAPG) stimulates their melanogenesis and dendrite formation

“…In acquired dermal melanocytosis, the fully pigmented dendrites of dermal melanocytes embracing elastic fibers, but without evidence of phagocytosis of these fibers. Furthermore, non-pigmented c-kit-and/or TRP-2-positive immature melanocytes were found in the dermis of the lesions, which implied there were preexisting immature melanocytes and through some factors' activation, they became differentiated to produce pigment [2]. Based on these findings we hypothesize that elastic fibers may play a role in regulating the development of melanocyte precursors.…”

Eponyms, Morphology, and Pathogenesis of Some Less Mentioned Types of Melanocytic Nevi

“…Spindle-shaped c-kit-positive melanocytes with brown granules are evident in the middle and upper dermis 33 (in contrast to Ota nevus, which has melanocytes in the upper and lower dermis). In the ultrastructural study, melanosomes are in stages II-IV of melanization, 28 mostly in stage IV.…”

“…Synonyms for Hori nevus and Sun nevus: naevus fuscocaeruleus zygomaticus 31 ; acquired dermal melanocytosis 29,33 ; acquired bilateral nevus of Ota-like macules 34,35 ; acquired symmetrical dermal melanocytosis. 29 Synonyms for Hidanos nevus: acquired dermal melanocytosis of the face and extremities.…”