Clinical and histologic findings in diffuse melanosis cutis. Patient #1 with blue-gray patches on his back (A), histologically confirmed as diffuse melanosis cutis, and melanuria (B) manifesting after 2 infusions of pembrolizumab. Patient #2 demonstrated diffuse melanosis cutis affecting his face and upper body (C) as well as melanuria (D) after only 1 infusion of pembrolizumab. Histologic examination (E) of dark gray patches on the neck of patient #2 showed characteristic changes of diffuse melanosis cutis with perivascular and interstitial groups of histiocytes (melanophages) with small-grained melanin below a regular epidermis (indicated by black arrows; hematoxylin and eosin staining, magnification 200, inlay 400).
From: Thiem A, Schummer P, Ueberschaar S, et al. Early onset of diffuse melanosis cutis under pembrolizumab therapy illustrates the limitations of anti-PD-1 checkpoint inhibitors. Melanoma Res 2018; 28:465. DOI:
10.1097/CMR.0000000000000458. Copyright © 2018. Reproduced with permission from Wolters Kluwer Health. Unauthorized reproduction of this material is prohibited.
