Riehl Melanosis (Pigmented Contact Dermatitis) Differential Diagnoses

Updated: May 27, 2021
  • Author: Elizabeth K Satter, MD, MPH; Chief Editor: William D James, MD  more...
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Diagnostic Considerations

Also consider the following [36] :

  • Drugs: Several classes of drugs induce hyperpigmentation, including minocycline, antimalarials, psychotropic drugs, chemotherapeutic agents, zidovudine, and psoralens. Also see Drug-Induced Pigmentation.

  • Erythromelanosis follicularis faciei et colli: This is characterized by symmetric reddish-brown pigmentation of the preauricular and maxillary areas, with multiple pinpoint follicular papules superimposed. Keratosis pilaris also may be noted. [37]

  • Friction melanosis: Brown or black hyperpigmentation unaccompanied by dermatitis or pruritus characterizes friction melanosis. It is seen primarily over the long bones, knees, elbows, and scapula. It occurs secondary to vigorous rubbing of the skin with nylon towels or brushes when bathing. [6]

  • Hori nevus or acquired nevus of Ota: This acquired facial hyperpigmentation is usually seen in women of Asian descent who are aged 20-70 years. It manifests clinically as bilateral blue-gray to gray-brown macules along the zygomatic area and, less often, on the forehead, upper-outer eyelids, and nose. Histologically, spindle-shaped dendritic melanocytes are present in the dermis and are scattered among collagen bundles. Melanophages usually are not present.

  • Lichen planus pigmentosus and actinic lichen planus: Brown to gray-brown macules evolve into diffuse/reticulated patches in sun-exposed skin and annular red-brown plaques or hyperpigmented patches primarily on sun-exposed skin, respectively. [3]

  • Thiazide leukomelanoderma: This is also known as photoleukomelanodermatitis Kobori, [38] and it is a reticular leukoderma with patchy hyperpigmentation, which can help differentiate it from Riehl melanosis. [39]

Differential Diagnoses