An Unusual Case of Congenital Dermal Melanocytosis

Abstract

Dermal melanocytosis is characterized by the presence of ectopic melanocytes in the dermis. The most common forms include the Mongolian spot, blue nevus, nevus of Ota, and nevus of Ito. Some types of dermal melanocytosis do not fit into any of these morphologic categories, however. Our case demonstrated an extensive amount of uniform deep blue patches of nevi with unilateral distribution on the left face, neck, chest, shoulder, and back. On histopathologic examination, a number of elongated melanocytes scattered throughout the dermis were found. We herein report a case of congenital unilateral dermal melanocytosis. (Ann Dermatol 22(4) 460∼462, 2010)

The spectrum of benign dermal dendritic melanocytic proliferations

“…As BN occasionally presents with macular lesions, other major variants of DMs (MS, naevus of Ota and naevus of Ito) clinically present as patchy lesions (Table ) . They are grouped based on their anatomical location, as mentioned above, and also due to their tendency to fade or persist into adulthood (Table ) . These lesions are usually asymptomatic but may rarely be associated with sensory changes in the involved skin…”

“…Congenital dermal melanocytosis (CDM) is generally referred to the congenital patchy dermal melanocytic proliferations, which do not fit into the well‐defined morphological categories of DMs in terms of clinical distribution . Their histopathological features are similar to naevus of Ota and naevus of Ito (Figs b,c, b,c).…”

“…2 They are grouped based on their anatomical location, as mentioned above, and also due to their tendency to fade or persist into adulthood (Table 4). 2,13,[51][52][53][54][55][56][57][58] These lesions are usually asymptomatic but may rarely be associated with sensory changes in the involved skin. 59…”

“…8d). These atypical DMs have been reported by different terms such as 'congenital unilateral dermal melanocytosis, 54 ' 'atypical dermal melanocytosis, 70 ' 'bilateral dermal melanocytosis with a dermatomal pattern, 80 ' 'congenital segmental dermal melanocytosis 81 ' and 'dermal melanocyte hamartoma 85 ' based on distribution pattern. Interestingly, our patient ( Fig.…”

“…107 Four possible theories have been proposed about ADM's pathogenesis: migration of melanocytes from hair bulb to dermis, descendance of melanocytes from epidermis, reactivation of pre-existing dormant dermal melanocytes or secondary development of DM caused by dermal inflammation. 92 It is assumed that dermal melanocytes which are present since birth 108 are either activated by various triggering factors such as pregnancy, 92 trauma, 97 previous inflammatory dermatoses, 98,109 hormonal treatment 104 and PUVA therapy 107 or Table 4 Epidemiological, clinical and histological features of main patchy dermal melanocytoses 2,13,[51][52][53][54][55][56][57][58] Mongolian spot 13,[52][53][54][55][56] Naevus of Ota 2,51,54,57,58 Naevus of Ito 2,54 Epidemiology Asian, African American and Native American population Benign dermal dendritic melanocytic proliferations show a gradual increase in melanin synthesis by increasing age without a known aetiology. 108 Large plaque-type blue naevus with subcutaneous cellular nodules (LPTBN-SN)…”