Acquired dermal melanocytosis
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Synopsis

Acquired dermal melanocytosis (ADM) is a rare, benign pigmentary disorder characterized by dark gray or brown macules and patches, most commonly on the face (also known as Hori nevus and acquired bilateral nevus of Ota-like macules). Other uncommon locations that have been reported include the extremities, back, and trunk.
Onset of facial lesions is usually in late adolescence or early adulthood. Patients with extrafacial ADM have a variable age of onset of pigmentation. While the majority of facial cases occur in female patients of East Asian origin, extrafacial presentation has a more varied sex and ethnic distribution. Patients usually have darker skin phototypes (Fitzpatrick skin phototype III or greater).
The etiology and pathogenesis of ADM is unclear. It is believed that immature dermal melanocytes may be activated by a trigger such as ultraviolet radiation, chronic inflammation, chemical exposure, or excessive sex hormones (ie, estrogen).
Related topic: congenital dermal melanocytosis
Onset of facial lesions is usually in late adolescence or early adulthood. Patients with extrafacial ADM have a variable age of onset of pigmentation. While the majority of facial cases occur in female patients of East Asian origin, extrafacial presentation has a more varied sex and ethnic distribution. Patients usually have darker skin phototypes (Fitzpatrick skin phototype III or greater).
The etiology and pathogenesis of ADM is unclear. It is believed that immature dermal melanocytes may be activated by a trigger such as ultraviolet radiation, chronic inflammation, chemical exposure, or excessive sex hormones (ie, estrogen).
Related topic: congenital dermal melanocytosis
Codes
ICD10CM:
L81.9 – Disorder of pigmentation, unspecified
SNOMEDCT:
414032001 – Disorder of pigmentation
L81.9 – Disorder of pigmentation, unspecified
SNOMEDCT:
414032001 – Disorder of pigmentation
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Nevus of Ota
- Nevus of Ito
- Riehl melanosis
- Lichen planus actinicus
- Lichen planus pigmentosus
- Exogenous ochronosis
- Alkaptonuria (congenital ochronosis)
- Melasma
- Blue nevus
- Tattoo
- Melanoma
- Lentigo maligna
- Lentigo maligna melanoma
- Drug-induced pigmentation
- Ecchymoses
Best Tests
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Management Pearls
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Therapy
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Drug Reaction Data
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.
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References
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Last Reviewed:06/09/2019
Last Updated:08/17/2021
Last Updated:08/17/2021

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