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Dr. Alpana Mohta Ranka, MD, DNB, IFAAD, is a dual-board-certified dermatologist with over 90 research publications in peer-reviewed scientific journals.


Melanosis: Types, Causes, and Management

Updated: May 5

Melanosis, a term derived from "melanin," the pigment responsible for skin, hair, and eye color, refers to the darkening or discoloration of various body tissues and organs. This phenomenon can occur in different regions of the body. In this comprehensive guide, we will delve into the world of melanosis, exploring its various types, causes, and management strategies.

Periorbital melanosis


Table of Contents:


What is Melanosis?

Melanosis is a benign condition characterized by the presence of excess melanin, the pigment responsible for skin color, in various body tissues. It can occur in both visible areas like the skin and mucous membranes or internally within organs.

Types of Melanosis

Cutaneous Melanosis:

This form of melanosis affects the skin and is characterized by the darkening of the skin due to an excess of melanin. It can occur in areas exposed to the sun, such as the face and arms. Apart from post-inflammatory hyperpigmentation, the two most common forms of cutaneous melanosis are pigment demarcation lines and periorbital melanosis (commonly known as "dark circles").

Pigmentary Demarcation Lines

Pigmentary Demarcation lines are a common benign form of pigmentation marked by abrupt shifts between darker and lighter skin tones. The most common sites include limbs and faces, with occasional traces on the trunk. These lines are more prevalent in Japanese skin and skin of color. There is a higher occurrence of pigment demarcation lines in females, notably during pregnancy.

Periorbital Melanosis

Periorbital melanosis is often attributed to an extension of pigmentary demarcation lines on the face. Factors such as genetics, inadequate sleep, stress, and underlying medical conditions are also contributory.

To learn more about another form of cutaneous melanosis that impacts the areas around the nose and mouth due to a fungal infection, refer to this article on seborrheic melanosis.

Mucosal Melanosis:

Mucosal melanosis is a general term for melanin-related discoloration of various mucous membranes throughout the body, which can include the mouth, nose, and genital regions. For a detailed understanding of genital melanosis, you can refer to our article on Vulvar Melanosis and Penile Melanosis.

Oral Melanosis:

Oral melanosis refers to the darkening of the oral mucous membranes, which can include the gums, cheeks, and palate. Melanotic macule is the most common form of oral melanosis. These benign lesions are more common in females and happen due to localized increases in melanin production. The vermilion border of the lip is the most common site of melanotic macules.

Other common causes of oral melanosis include:

  1. Smoking (smoker's melanosis)

  2. Medications (chloroquine, hydroxychloroquine, oral contraceptives, other hormonal pills, minocycline, chemotherapy, zidovudine, and amiodarone)

  3. Systemic diseases like vitamin B12 deficiency, Addison's disease, and Peutz-Jeghers syndrome.

Ocular Melanosis:

Ocular melanosis involves the pigmentation of the eye, particularly the iris and conjunctiva. Changes in eye color or the presence of dark spots on the eye's surface may be indicative of ocular melanosis. Ocular melanosis can also be a manifestation of neurocutaneous melanosis.

Rectal and Anal Melanosis:

Melanosis can also affect the rectum and anal region, leading to darkening of the mucous membranes. This condition may be associated with gastrointestinal issues or other systemic diseases.

Nail Melanosis:

Nail melanosis or melanonychia is characterized by changes in the color or pigmentation of the nails. It can affect both fingernails and toenails.

Physiological causes of nail melanosis encompass racial melanonychia, often seen in people with skin of color, and occurrences during pregnancy.

Local and regional influences like repeated trauma from nail-biting, ill-fitting footwear, and conditions like carpal tunnel syndrome.

Dermatological factors such as chronic paronychia, psoriasis, and amyloidosis also play a role.

Systemic causes involve endocrine disorders like Addison's disease, thyroid disease, vitamin B12 deficiency, and syndromes such as Peutz-Jegher and Laugier-Hunziker syndrome.

Melanocytic hyperplasia, lentigo, and nevi, both congenital and acquired, can also contribute to nail discoloration.

Systemic Melanosis:

Systemic melanosis refers to melanin accumulation within internal organs like the liver, heart, or gastrointestinal tract. It can be associated with certain medical conditions. To learn more about neurocutaneous melanosis, a rare form of systemic melanosis, read our article on Neurocutaneous Melanosis.

Causes of Melanosis

The causes of melanosis can vary depending on the type and location of the condition. While some melanosis types are primarily associated with natural processes, others may be influenced by external factors or underlying medical conditions.

Symptoms and Diagnosis

Melanosis can manifest with different symptoms, including changes in skin color, texture, or the appearance of moles or dark spots. Diagnosis often involves a thorough examination and, in some cases, a biopsy to rule out malignancy.

Treatment and Management

Managing melanosis depends on its type and location. While many cases require no treatment, others may benefit from cosmetic procedures or lifestyle changes. We discuss these management options in detail in our respective articles. For example, in conditions such as tinea cruris, using a simple jock itch cream can help in resolving the condition.

Preventive and Precautionary Measures

Preventing melanosis involves practicing good sun protection, maintaining proper hygiene, and being vigilant about changes in your skin or mucous membranes. Vitamin B12 deficiency, an exceedingly common cause of melanosis, is very prevalent in vegetarians and vegans. Therefore, consuming a diet rich in vitamins and minerals can help in preventing cutaneous melanosis.

Early detection is often key to effective management. If you observe a sudden change in your body's color or change in a preexisting pigmented lesion or mole, consult your dermatologist or physician at the earliest.


Melanosis is a fascinating condition that can occur in various forms throughout the body. While it is typically benign, it is essential to understand its types, causes, and management strategies.


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