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

• Comedo Naevus
• Comedo Nevus
• Comedone Naevus 

What is Nevus Comedonicus? (Definition/Background Information)

• Nevus Comedonicus is a rare skin abnormality that affects the folliculosebaceous glands. It is characterized by closely situated, elevated papules on the skin, causing ‘blackheads’. They are thought to originate from a defect causing keratinous plugs of hair/oil follicular units. However, the cause of Nevus Comedonicus is unknown
• Nevus Comedonicus is present at birth in half the cases. Most of the remainder cases occur before age ten years, although later onset is sometimes seen. The condition typically affects only one side of the body; the commonly affected areas being the face, neck, chest, back, calves, and in rare cases, the penis
• Papules (small, raised skin forms) that form on the skin can either be singular or multiple, affecting large areas of the body. Other than being present as a cosmetic issue, these papules usually do not cause any symptoms; although sometimes, itching may be present
• A diagnosis of Nevus Comedonicus may be made using a physical examination, dermoscopy (examination of the skin using a magnifying lens), and a tissue biopsy
• If the papules are small in size, they can be surgically removed; if they are extensive, topical creams are prescribed to treat them. Without treatment, the papules will grow and become worse. With prompt and appropriate treatment, the prognosis of Nevus Comedonicus is good
• Nevus Comedonicus can be part of Nevus Comedonicus syndrome, which consists of eye abnormalities (such as cataracts), bone abnormalities, and central nervous system abnormalities

Who gets Nevus Comedonicus? (Age and Sex Distribution)

• Nevus Comedonicus can occur at birth, or anytime up to middle age. Although, 50% of all cases are seen at birth
• Both male and female genders are equally prone to Nevus Comedonicus 
• This skin disorder can occur worldwide; there is no ethnic or racial preference noted
• While it typically does not run in families, rare cases of increased incidence within families have been reported

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

• The risk factors of Nevus Comedonicus have not been currently established
• In rare cases, Nevus Comedonicus syndrome is a risk factor

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones 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 Nevus Comedonicus? (Etiology)

• The exact cause of Nevus Comedonicus occurrence is unknown. It is believed to occur spontaneously, which leads to defects during the formation of hair follicles
• Nevus Comedonicus is also present in the very rare Nevus Comedonicus syndrome in which the brain, bone, and eye may be affected
• Nevus Comedonicus is rarely associated with other benign tumors of the skin, such as trichoepithelioma, hidradenoma papilliferum, and syringocystadenoma papilliferum
• Researchers have documented that certain genetic changes may contribute to the development of Nevus Comedonicus. However, cases where these specific genetic mutations have been observed are very rare. Thus, studies regarding genetic changes are currently very limited

Presently, research is being undertaken to improve understanding of Nevus Comedonicus.

What are the Signs and Symptoms of Nevus Comedonicus?

Common signs and symptoms of Nevus Comedonicus include: 

• Skin papules (small, raised skin lesions) are typically concentrated on only one side of the body 
• Papules may be present on the face, neck, chest, back, calves, or penis
• There may be itching sensations at the lesion sites
• In rare cases, there may be bone and brain abnormalities (if associated with Nevus Comedonicus syndrome, which is a very rare syndrome)
• Accessory breast tissue formation (rarely)

How is Nevus Comedonicus Diagnosed?

Nevus Comedonicus is diagnosed using the following methods: 

• A thorough physical examination and a complete medical history 
• Dermoscopy: A dermoscopy is a diagnostic tool in which a dermatologist examines the affected skin, using a special magnified lens
• Tissue biopsy: A tissue biopsy is collected and sent to a laboratory for pathological examination. A pathologist examines the biopsy under a microscope and is able to arrive at a definitive diagnosis
• Radiological imaging studies: These studies can include an X-ray or CT scan of the affected region. If bone defects are also present, an MRI scan of the affected region can also be done. These studies are usually performed, if Nevus Comedonicus syndrome is also present
• Differential diagnosis, to eliminate other tumors/conditions are often considered, before arriving at a definitive diagnosis

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 Nevus Comedonicus?

Nevus Comedonicus can cause the following complications. These include:

• One of the most common complications is infection. If the skin lesions are open, they are susceptible to bacterial infection and antibiotics may be necessary to treat them
• Skin lesions that develop due to Nevus Comedonicus are often itchy; scratching the lesions may cause scarring to occur. If this becomes excessive, scarring can cause cosmetic issues and lead to emotional distress and self-esteem issues

How is Nevus Comedonicus Treated?

Nevus Comedonicus does not have a cure. Instead, treatment options are available to ease one’s symptoms and control the skin lesions. The healthcare provider will determine the best course of treatment depending on each individual’s specific circumstances. The treatment may include:

• Topical steroids and topical retinoids are often prescribed to reduce swelling and control itching
• If the lesions are small, they can be surgically excised. If the lesions are larger in size, laser therapy can be used to mitigate them
• Follow-up care with regular screening and check-ups are important

A team of healthcare providers is necessary to treat the very rare Nevus Comedonicus syndrome. The  eye, brain, and bone defects present will require a team of neurologists, ophthalmologists, orthopedic surgeons, dermatologists, and social workers. A multi-disciplinary approach gives patients with Nevus Comedonicus syndrome a better chance at a positive outcome.

How can Nevus Comedonicus be Prevented?

Currently, there are no known preventative measures available for Nevus Comedonicus. 

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

• The skin lesions caused by Nevus Comedonicus can progress and become worse, if no treatment is provided
• With prompt treatment and regular follow-ups, the skin condition can be managed and the prognosis is good 

Additional and Relevant Useful Information for Nevus Comedonicus:

An epidermal nevus is a benign, yellowish-brown, wart-like skin lesion, which is commonly present at birth, or develops during childhood. The skin lesions may appear as plaques or papules, and are usually present in the trunk or extremities. 

The following article link will help you understand epidermal nevus.

https://www.dovemed.com/diseases-conditions/epidermal-nevus-en/