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

• LBCN (Linear Unilateral Basal Cell Nevus)
• Linear Nevoid Basaloid Follicular Hamartoma
• Linear Unilateral Basal Cell Naevus

What is Linear Unilateral Basal Cell Nevus? (Definition/Background Information)

• Linear Unilateral Basal Cell Nevus (LUBCN) is an uncommon benign tumor of hair follicle. LUBCN is termed a hair follicle hamartoma (abnormal growth) that appears as a linear set of skin lesions (macules and papules). The condition is asymptomatic and does not generally require any treatment
• Even though non-malignant, Linear Unilateral Basal Cell Nevus presents significant overlapping features with nevoid basal cell carcinoma syndrome, an aggressive malignancy, and other basal cell carcinoma (BCC) subtypes
• This raises a concern of cancer and warrants a closer medical evaluation and follow-up of the tumor. However, it is reported that Linear Unilateral Basal Cell Nevus displays a non-aggressive and non-progressive course. The outcomes for individuals with this tumor type is generally excellent

Who gets Linear Unilateral Basal Cell Nevus? (Age and Sex Distribution)

• Linear Unilateral Basal Cell Nevus is a rare tumor that are mostly observed at or following birth; however, some cases may be only diagnosed into adulthood (late-onset)
• It is seen to occur in both males and females
• It may be noted across individuals of different races and ethnic background

What are the Risk Factors for Linear Unilateral Basal Cell Nevus? (Predisposing Factors)

• There are no clearly identified risk factors for Linear Unilateral Basal Cell Nevus (LUBCN)
• According to medical research, no family history of the tumor has been established 

Per medical literature, the following bone abnormalities have been occasionally associated with LUBCN. However, the relationship between LUBCN and these abnormalities is unknown.

• Abnormal bone mineralization/formation
• Anodontia - absence of teeth
• Osteoma cutis - bone formation in skin
• Scoliosis - abnormally curved spine

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 Linear Unilateral Basal Cell Nevus? (Etiology)

Currently, the cause of development of congenital Linear Unilateral Basal Cell Nevus (LUBCN) is not well-understood. The condition is not known to be inherited.

• LUBCN presents significant similarity with the malignant tumors nevoid basal cell carcinoma syndrome and other basal cell carcinoma variants. However, genetic mutations found in these basal cell carcinomas (mostly involving the PTCH and SMO genes) are not noted in LUBCN; thus, medical experts feel that it may be unrelated to these malignancies
• LUBCN is observed to form along the Blaschko lines. The Blaschko lines are invisible lines, which are defined as regions of the body where skin growth occurs in a systematic manner during fetal development. They are present all over the body

What are the Signs and Symptoms of Linear Unilateral Basal Cell Nevus?

The signs and symptoms of Linear Unilateral Basal Cell Nevus include:

• Presence of many macules and papules roughly along a straight line (linear pattern)
  • A macule indicates the presence of a flat, distinct, discolored area of skin less than 1 cm wide. A macule usually does not involve any change in the thickness or texture of the affected skin
  • A papule is a small, well-defined (with clear borders), discolored, raised skin bump
• These lesions are skin-colored or present reddish discoloration and are seen along the Blaschko lines
• The lesions may be present on the trunk, shoulders, or arms
• Hypopigmented areas (patches of lighter skin) may be noted around the lesions
• Rarely, LUBCN may be associated with comedones (whiteheads and blackheads)
• Pain, itching, discomfort, or burning sensation is not reported

Also, no other systemic signs and symptoms are known to be associated with LUBCN.

How is Linear Unilateral Basal Cell Nevus Diagnosed?

A diagnosis of Linear Unilateral Basal Cell Nevus may be established by the following tests and procedures:

• 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 (if required): 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

It is very important to undertake a differential diagnosis to eliminate the following skin conditions before arriving at a definitive diagnosis:

• Linear basal cell carcinoma
• Unilateral nevoid basal cell carcinoma syndrome (NBCCS)

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 Linear Unilateral Basal Cell Nevus?

There are generally no complications associated with a Linear Unilateral Basal Cell Nevus. However, in some cases, the following may be noted:

• Cosmetic concerns
• Emotional stress from concerns of a malignancy

How is Linear Unilateral Basal Cell Nevus Treated?

• There is generally no treatment required for Linear Unilateral Basal Cell Nevus, which is a benign skin lesion
• Whenever treatment is necessitated, it is mainly for cosmetic reasons. The treatments may involve surgery, laser therapy, or cryosurgery, based on the healthcare provider’s assessment

However, regular follow up visits with the healthcare provider is recommended.

How can Linear Unilateral Basal Cell Nevus be Prevented?

Currently, there are no known means of preventing Linear Unilateral Basal Cell Nevus occurrence.

What is the Prognosis of Linear Unilateral Basal Cell Nevus? (Outcomes/Resolutions)

The prognosis of Linear Unilateral Basal Cell Nevus is typically excellent since it is a benign and asymptomatic lesion.

Additional and Relevant Useful Information for Linear Unilateral Basal Cell Nevus:

• There is no evidence to prove that the tumor formation is influenced by one’s dietary choices
• 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

The presence of dirt on the body is not a causative factor for the condition. However, it helps to be clean and hygienic, which may help the condition from getting worse