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

• Bullous Mastocytoma
• Localized Mastocytoma of Skin
• Solitary Mastocytoma

What is Mastocytoma of Skin? (Definition/Background Information)

• Mastocytosis is a rare disorder that results from often abnormal and excessive numbers of mast cells in the skin and, rarely, in the organs. When the skin is affected, it is known as cutaneous mastocytosis; when the skin and other organs are affected, it is known as systemic mastocytosis
• Mast cells, which reside in the connective tissue, store chemicals important to initializing the inflammatory and allergic responses. Once activated, mast cells release chemicals including heparin, histamine, and serotonin that stimulate the body’s inflammatory response
• Mastocytoma of Skin is a form of cutaneous mastocytosis typically appearing as a single skin lesion that is red/yellow brown in color. The condition affects both children and adults but is predominantly self-limited and resolves over time. It is also known as Solitary Mastocytoma, and is the second-most common type of skin mastocytosis
• The tests to diagnose Mastocytoma of Skin include general physical examinations, blood tests, skin biopsies, and genetic testing to detect KIT gene mutations. An absence of systemic signs and symptoms is important in establishing a diagnosis of the condition
• Once the physical examination and any relevant tests are done, the reassuring diagnosis of Mastocytoma of Skin can be made. This makes the issue of systemic disease irrelevant. Very rarely, as children get older, they can develop maculopapular cutaneous mastocytosis
• Presently, there are no standard curative options for Solitary Mastocytosis. Generally, management of the symptoms and controlling the inflammatory response is needed, which may involve anti-histamine treatment

Who gets Mastocytoma of Skin? (Age and Sex Distribution)

• Most cases of Mastocytoma of Skin are observed during the first 12 months following the birth of the child. Adults are also affected but to a lesser extent than children
• Both males and females are equally susceptible to the condition
• Worldwide, it can affect all racial and ethnic groups

What are the Risk Factors for Mastocytoma of Skin? (Predisposing Factors)

• A majority of Mastocytoma of Skin cases are observed during infancy and early childhood
• A positive family history is rarely observed in mastocytosis; and, no other specific risk factors have been identified

However, in general, the following are believed to increase one’s susceptibility to mastocytosis:

• Smoking
• Exposure to radiation and industrial chemicals
• Chemotherapy
• In rare cases, viral infections

These factors are presumably not in play with childhood-onset mastocytosis.

There are also a host of factors that may trigger histamine release further aggravating the skin signs and symptoms in mastocytosis. Some of these include:

• Medications such as opioid painkillers, non-steroidal anti-inflammatory drugs (NSAIDs), vitamin supplements, antibiotics, anticholinergics, etc.
• Venom injection from snake bites and bee stings
• Emotional stress
• Lack of sleep
• Hot or cold weather, and temperature changes
• Certain viral and bacterial infections
• Iatrogenic factors such as application of local anesthetic, vaccines, administration of contrast media, and even certain invasive procedures

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 Mastocytoma of Skin? (Etiology)

The cause of formation of Mastocytoma of Skin is mostly due to mutations in the KIT gene.

• In a vast majority of cases, the condition occurs sporadically. In some cases, it is caused by unknown factors
• Occasionally, when cutaneous mastocytosis is inherited, an autosomal dominant pattern of inheritance is noted

What are the Signs and Symptoms of Mastocytoma of Skin?

The signs and symptoms of Mastocytoma of Skin may vary from one individual to another. It may be mild or severe. The signs and symptoms may include:

• The appearance of a reddish-brown or yellowish-brown lesion on skin
• The skin lesion is typically solitary and may appear flat or raised
• The arms, legs, or the body may be affected
• Blister formation may be noted
• Darier sign: It is the activation of mast cells by rubbing an area of the affected skin, which results in reddish skin that is itchy and swollen. This is usually seen in young children, within a few minutes of rubbing/scratching the skin
• Severe itching (pruritus), which may worsen with factors such as temperature changes, physical activity, or certain medication

The presence of triggers, such as certain medications, sunlight, or medical procedures, may cause a flare up (inflammatory response) of the signs and symptoms.

How is Mastocytoma of Skin Diagnosed?

The following are some tests and exams that may be used in the diagnosis of Mastocytoma of Skin:

• Physical exam to detect skin abnormalities and comprehensive medical history evaluation
• The healthcare provider may attempt to elicit the Darier’s sign by rubbing or stroking one or more of the skin lesions. This may be often the only noninvasive test needed to establish a diagnosis. If systemic disease is considered based on medical history or a general physical exam, further tests may be undertaken
• Blood smear to detect:
  • Increased numbers of mast cells
  • Abnormally-shaped mast cells
  • Reduced numbers of red blood cells (anemia)
  • Reduced numbers of platelets (thrombocytopenia)
• Blood tests to detect:
  • Elevated total tryptase levels which can indicate systemic disease
  • Elevated lactate dehydrogenase which is a prognostic factor in systemic disease
  • Elevated alkaline phosphatase levels
• Skin biopsy to detect:
  • Clusters of mast cells
  • Abnormally-shaped mast cells
• Genetic tests to detect a KIT mutation, if necessary

In almost all cases, the only needed tests would be trying to provoke Darier’s sign, or a skin biopsy.

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 Mastocytoma of Skin?

Following are some of the complications that may arise from Mastocytoma of Skin:

• Emotional stress
• Uncontrollable inflammatory and allergic reactions; severe reactions may result in anaphylaxis that can be life-threatening
• Treatment-related complications

Localized itching is almost always the only sign, without complications.

How is Mastocytoma of Skin Treated?

Mastocytoma of Skin treatment depends on the severity of the skin condition, and on the age and health status of the individual. However, there is no cure for the condition.

• If the condition is confined/localized to a region and is “symptomless”, no treatment may be necessary
• High potency corticosteroid cream application only to the lesion(s) can rapidly resolve the issue. If the lesion continues to be symptomatic, occasional topical steroid courses can be used
• Avoiding and/or controlling the triggers that worsen the condition is important
• Antihistamine therapy may be recommended in some individuals
• Symptomatic cutaneous mastocytosis may be treated with phototherapy (PUVA or UVB)
• In case of anaphylaxis, subcutaneous epinephrine or adrenaline may be administered

Periodic monitoring or follow-up of the condition with the healthcare provider is recommended.

Note: As high potency corticosteroids have a higher risk of side effects in infants and children, particular care must be given in counseling to sparingly use these medications. It is also prudent to limit the amount of medication dispensed.

How can Mastocytoma of Skin be Prevented?

Presently, it may be difficult to avoid Mastocytoma of Skin. However, some of the following factors may be considered:

• If there is a family history of the condition, then genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• Identify, avoid, or control the triggers for the condition

Other home care tips include:

• Always keeping skin clean and healthy
• Wearing gloves while applying ointment on the blisters is advised
• Children’s nails should be cut short so that infection from scratching the blisters can be avoided
• Frequent washing of hands is recommended
• The affected child or adult is best advised to stay indoors in case of any “flare ups”
• Patients may be advised to carry injectable epinephrine to overcome serious allergic reactions

Some narcotics used in general anesthesia can cause mast cells to release their chemicals, including histamine, leading to shock. Patients must be told to inform all physicians of their mast cell disease to protect them from this. A ‘permanent’ passive reminder such as a MedicAlert device is strongly recommended.

What is the Prognosis of Mastocytoma of Skin? (Outcomes/Resolutions)

Mastocytoma of Skin is usually not life-threatening; it generally resolves over time, in a vast majority of cases.

Additional and Relevant Useful Information for Mastocytoma of Skin:

Recently, it has been shown that the chemicals released by mast cells also affect the activities of the bone cells. These include bone-building osteoblasts and bone-digesting osteoclasts. Mast cells have been linked to stimulation of osteoclasts and inhibition of osteoblasts, resulting in bone deficiencies.