Case Presentation
A 46-year-old Caucasian woman presented with a 10-year history of an asymptomatic progressive darkening of the skin. There was no previous history of inflammation, and she denied the use of medications. Examination revealed symmetric blue-gray patches involving the face, trunk (Figure 1, A and B) and extremities. Dermoscopy showed a diffuse reticulated-homogenous brown-gray pigmentation (Figure 1C). Skin biopsy revealed multiple spindle-shaped dendritic melanocytes in the dermis (Figure 1D) and immunohistochemical staining was positive for Melan-A and HMB-45.
Figure 1.
(A) and (B) Remarkable blue-gray pigmentation on the trunk. (C) Dermoscopy (10x) revealing a diffuse reticulated-homogenous brown-gray pigmentation. (D) Histopathology showing multiple spindle-shaped dendritic melanocytes in the dermis (arrows).
Teaching Point
Acquired dermal melanocytosis is a rare pigmentary disorder and its etiology remains unknown. Three theories may explain this disorder: migration of epidermal melanocytes to the dermis; migration of hair bulb melanocytes; or reactivation of pre-existing latent dermal melanocytes triggered by local inflammation or an unknown stimulus [1,2]. Melanin-containing dendritic melanocytes can be seen in the upper-middle portions of the dermis and, with the Tyndall effect, they result in a brown to bluish-gray skin pigmentation [2].
Footnotes
Competing interests: None.
Authorship: All authors have contributed significantly to this publication.
Informed consent: Written informed consent for publication of clinical details and clinical images was obtained from the patient.
Funding: None.
References
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