What is in the Differential Diagnosis for Brown and Grey Skin Conditions?

Patient Presentation
A 14 year-old male came to clinic for his health examination visit and to followup for obesity. He had increased his physical activity over the past 6 months but had not made dietary changes.

The pertinent physical exam showed an obese male with normal vital signs. He had gained 3.4 kg since his last visit and had increased his BMI to 37.2. His skin showed velvety-brown lesions on his neck and upper back. The rest of his examination was non-contributory. The diagnosis of a teenage male with obesity, acanthosis nigricans and increasing BMI trend was made. He was commended for increasing his exercise but also counseled again about healthy eating. After his laboratory evaluation showed abnormal lipids, hemoglobin A1c of 6.7%, and elevated liver enzymes, he was also referred to the cardio-metabolic clinic for additional evaluation and management including meeting with a dietician.

This is the fourth in a short case series of differential diagnoses of colored skin conditions.
An introduction to dermatological terminologies and information about colors can be found here.
A differential diagnosis by distribution and common pattern can be found here.
For red, orange and yellow conditions, a review can be found here.
For green, blue and purple conditions, a review can be found here.
For black and white conditions, a review can be found here.

Note that any color can be a normal variant for an individual or is physiologic for a given state.

Acanthosis nigricans causes dark brown-black patches or streaks in skin creases especially on the neck, armpits and groin. It has a velvety elevated texture. It is caused by insulin resistance.

Learning Point
Brown is produced in several ways. Combinations of red, yellow and black, or orange and black are the usual ways.
The differential diagnosis for brown skin conditions includes:

  • Skin
    • Acanthosis nigricans
    • Addison disease
    • Cushing syndrome
    • Drug induced hyperpigmentation
      • Topical or systemic medications often with additional skin exposure
    • Incontinentia pigmenti
    • Neoplasms
      • Langerhans cell histiocytosis
      • Lymphoma
      • Melanoma
    • Pigmented purpuric dermatosis
      • Petechiae
      • Purpura
      • Telangiectasis
    • Post-inflammatory hyperpigmentation
      • Cosmetics
      • Inflammation
      • Sun
      • Trauma
    • Pregnancy
    • Melasma
    • Riehl melanosis
    • Seborrheic keratosis
    • Stasis dermatitis
  • Nails
    • Chemical-induced
    • Incontinentia pigmenti
    • Melanonychia
    • Trauma
  • Mucosa
    • Infection
    • Peutz-Jegher syndrome
    • Laugier-Hunziker syndrome
    • Trauma

Grey is a combination of white and black. “An achromatic gray is a gray color in which the red, green, and blue codes are exactly equal….A chromatic gray is a gray color in which the red, green, and blue codes are not exactly equal, but are close to each other, which is what makes it a shade of gray.”
The differential diagnosis for gray skin conditions includes:

  • Skin
    • Ashy dermatitis (erythema dischromicum)
      • Dermal melanocytosis
      • Congenital dermal melanocytosis
      • Nevus of Ito or Ota
    • Drugs often with additional skin exposure
      • Antibiotics
        • Grey-baby syndrome with chloramphenicol
        • Tetracycline
      • Heavy metals
        • Gold
        • Iron
        • Silver
    • Incontinentia pigmenti
    • Hypomelanosis of Ito
    • Hemochromatosis
    • Lichen planus pigmentosis
    • Naegeli-Franceschetti-Jadassohn syndrome
    • Ochronosis
    • Organ failure (late)
    • Trauma
  • Hair
    • Chemical-induced
    • Silvery hair syndrome
  • Nails
    • Chemical-induced
    • Incontinentia pigmenti

Questions for Further Discussion
1. What brown skin conditions do you see most often?
2. What grey skin conditions do you see most often?
3. What are indications for referral to a dermatologist?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Rashes

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Abdel-Naser MB. The color of skin: gray diseases of the skin, nails, and mucosa. Clinics in Dermatology. 2019;37(5):507-515. doi:10.1016/j.clindermatol.2019.07.011

Kutlubay Z, Cesur SK, Askın O, Tuzun Y. The color of skin: brown diseases of the skin, nails, and mucosa. Clinics in Dermatology. 2019;37(5):487-506. doi:10.1016/j.clindermatol.2019.07.007

Shades of brown. In: Wikipedia. 2022. Accessed January 25, 2022. https://en.wikipedia.org/w/index.php?title=Shades_of_brown&oldid=1065742420

Shades of gray. In: Wikipedia. 2022. Accessed January 25, 2022. https://en.wikipedia.org/w/index.php?title=Shades_of_gray&oldid=1065573955

Visible spectrum. In: Wikipedia. 2021. Accessed January 4, 2022. https://en.wikipedia.org/w/index.php?title=Visible_spectrum&oldid=1062416030

Donna M. D’Alessandro, MD
Professor of Pediatrics, Universit