What are the other Names for this Condition? (Also known as/Synonyms)

• Mucinous Naevus

What is Mucinous Nevus? (Definition/Background Information)

• A nevus (plural nevi) is a mole on the skin that can occur on any part of the body. A Mucinous Nevus is a benign skin mole that may be present as a group of papules and plaques on the back, chest, or buttocks
• The exact cause of development of Mucinous Nevus is currently unknown. In nearly half of the cases, a congenital presentation is noted, meaning that the condition is present at birth. Some cases of Mucinous Nevus are acquired later in life
• The condition is diagnosed by a skin biopsy. When the biopsy specimen is examined under a microscope by the pathologist, there is a deposition of mucin within the dermis of skin; however, there no proliferation of melanocytes is noted
• In some cases, Mucinous Nevus may present complications including emotional stress due to cosmetic concerns and formation of scar tissue following surgery to remove the lesion
• Treatment is generally not required for Mucinous Nevus, unless it presents cosmetic issues. The prognosis is excellent with suitable treatment, since it is a benign lesion

Who gets Mucinous Nevus? (Age and Sex Distribution)

• Mucinous Nevus is a rare skin condition that is seen during the period between birth and early adulthood. Infrequently, it is diagnosed in older adults
• 50% of the cases are seen at birth, while the remaining 50% arise before individuals reach adulthood
• Both males and females are affected, though the male-female ratio is 3:1
• All racial and ethnic groups are affected and no predilection is observed
• Asians have a higher risk for Mucinous Nevus, even though the condition is observed around the world

What are the Risk Factors for Mucinous Nevus? (Predisposing Factors)

• Currently, there are no specific risk factors identified for Mucinous Nevus

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mucinous Nevus? (Etiology)

The cause of Mucinous Nevus formation is generally unknown. It is described as a type of connective tissue nevus.

• Some researchers considered it to be a hamartoma; but, it is not a “true nevus”, which is a proliferation of melanocytes (i.e., it is not a tumor of melanocytes)
• Mucinous Nevus may be congenital in nature, or acquired due to certain factors that are currently unknown

What are the Signs and Symptoms of Mucinous Nevus?

The signs and symptoms of Mucinous Nevus may include:

• Presence of brownish plaques and papules that are present in groups and appear as a nevus/mole
  • A papule is an area of abnormal skin tissue that is less than 1 centimeter around. Usually a papule has distinct borders, and it can appear in a variety of shapes
  • A plaque indicates a broad, raised area on the skin. A skin plaque is usually broader than it is high
• The size, number, and distribution of papules/plaques, may vary from one individual to another
• The benign nevi may form on any part of the body, but the back is affected the most
• Other regions include the chest, abdomen, trunk, and buttock

How is Mucinous Nevus Diagnosed?

A Mucinous Nevus is diagnosed through the following tools:

• Complete physical examination with evaluation of medical history
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis
• Differential diagnosis of other tumors presenting similar symptoms should be ruled out; hence, a skin biopsy is an important diagnostic tool

Note: Some pathologists classify Mucinous Nevus into two types based on the features observed under a microscope, namely connective tissue nevus of the proteoglycan (CTNP) type and combined epidermal-CTNP type.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mucinous Nevus?

There are frequently no complications that arise from a Mucinous Nevus.

• In some individuals, it may give rise to cosmetic concerns
• Scratching or itching of the lesions may lead to bleeding and ulceration. This can cause secondary bacterial or fungal infections to develop
• Surgical removal of the nevus may result in the development of scar tissue

How is Mucinous Nevus Treated?

The treatment measures for Mucinous Nevus may be dependent upon the severity of the signs and symptoms. No treatment may be required for some individuals, while in others, the following may be considered:

• The healthcare provider may choose to regularly observe the mole and a “wait and watch” approach may be undertaken
• Mild skin conditions may be treated using topical steroidal creams and applications
• Surgical excision and removal of the nevus, if necessary for cosmetic reasons, may be performed
• The benign nevus can also be excised through electrocautery surgical procedure, if required

How can Mucinous Nevus be Prevented?

Current medical research has not established a method of preventing the occurrence of Mucinous Nevus.

What is the Prognosis of Mucinous Nevus? (Outcomes/Resolutions)

• The prognosis of Mucinous Nevus is excellent on its complete excision and removal, in a majority of cases
• Since, it is a benign mole, the prognosis is excellent even with periodic observation, in some cases

Additional and Relevant Useful Information for Mucinous Nevus:

• Do not pick or scratch the moles
• Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that could potentially worsen the condition