Dermal Melanocytoses (Nevus of Ota and Ito, Mongolian Spot)

 Often evident at birth


image Occasionally manifest later in life

image Different clinical course

– Generally stable over time (nevus of Ota and Ito)

– Resolution with time (Mongolian spot)


image Blue to gray macule/patch


• Nevus of Ota
image Near/involving eye

• Nevus of Ito
image Shoulder area

• Mongolian spot
image Generally on back



Microscopic




• Dendritic melanocytes in dermis

• Dermis generally otherwise normal (without sclerosis)


Top Differential Diagnoses




• Blue nevus
image Clinically, confluent macule or patch of blue pigmentation, generally not present at birth

image Histologically dendritic/spindled melanocytes in dermis with variable numbers of melanophages

• Hori nevus
image Acquired in adulthood, female predominance

image More common in Asian populations

image Involves malar cheeks, generally bilateral

image Often composed of numerous brown macules that may become gray over time

• Becker nevus
image Clinically tan to brown patch on shoulder/upper back area; may show hypertrichosis within lesion

image Histologically: Basal layer melanin pigment, smooth muscle bundles in dermis, ± hypertrichosis

• Child abuse

image
Mongolian Spot in Sacral Region
This is the classic location for a Mongolian spot, over the sacral area. There may also be patches in other areas of the back.


image
Mongolian Spot on Arm
This is an aberrant Mongolian spot located on the arm. It was present at birth. These lesions overlap with blue nevi and do not always resolve.

image
Mongolian Spot at Low Magnification
This low-magnification view of a Mongolian spot shows a normal epidermis and pigmented cells image scattered through the dermis.

image
Mongolian Spot at High Magnification
This high-magnification view of a Mongolian spot shows dendritic melanocytes with cytoplasmic melanin pigment in the deep dermis.


CLINICAL ISSUES


Epidemiology




• Age
image Often evident at birth but occasionally manifest later

• Ethnicity
image More common in Asians

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Dermal Melanocytoses (Nevus of Ota and Ito, Mongolian Spot)

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