Pigmented Patches



Fig. 30.1
Upper panel reveals a young woman with type IV skin and confluent brownish, depressed, smooth patches characteristic of atrophoderma. Lower panel reveals a woman with type V skin and multiple ashy smooth macules, characteristic of ashy dermatosis




Case

A patient presents with multiple, acquired, smooth brownish patches.

Lesions are acquired, so congenital pigmentation, such as café au lait spots, are excluded; lesions are smooth and nonpalpable; hence, chronic hyperpigmented disorders, such as dermatitis and hyperpigmented mycosis fungoides (MF), are excluded.

The clinical differential diagnosis includes



  • erythema dyschromicum perstans EDP/ashy dermatosis


  • drug deposition


  • macular amyloidosis


  • melasma


  • lymphocytic macular arteritis (LMA)


  • post-fixed drug eruption (FDE)


  • phytophotodermatitis, and


  • atrophoderma.

Although lesions of atrophoderma appear brown, there is no increased pigmentation, unlike the other disorders in this group. The brownish appearance in atrophoderma is due to the way light is reflected from skin with atrophic dermis. The characteristic depressed border is easily detected, especially by using incident lighting. Without appreciating the border, a lesion of atrophoderma may be mistaken for macular hyperpigmentation.


Clinical Clues




1.

Clues based on patients’ ethnicity

 

Both melasma and macular amyloidosis are more common among individuals of Middle Eastern and Asian background. EDP/ashy dermatosis is common in individuals of color such as Latin Americans. LMA predominantly affects individuals of color that include Middle Eastern, African American, and Asian.



2.

Clues based on location

 

Melasma invariably involves the face and rarely the upper extremities as well. Macular amyloidosis almost always involves the upper back, and often is limited to the upper back.

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Nov 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Pigmented Patches

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