Mastocytosis is a rare medical disorder characterized by the abnormal accumulation of mast cells in various body tissues. These mast cells, a type of white blood cell and immune system component, are found throughout the body, including the skin, bone marrow, and internal organs. While mastocytosis can affect many body parts, this article focuses on its manifestations within the eyes.
Understanding Mastocytosis and Its Ocular Impact
Mast cells play a role in the body’s immune responses, acting as an alert system against foreign invaders. They are located in tissues throughout the body, including near blood vessels, and can release various chemical mediators such as histamine, tryptase, leukotrienes, and prostaglandins when activated. In mastocytosis, an overabundance or inappropriate activation of these mast cells leads to excessive mediator release, causing a range of symptoms.
When mast cells accumulate in ocular tissues, their mediator release can trigger inflammation in the eyes. Mastocytosis can be categorized as cutaneous, affecting only the skin, or systemic, involving internal organs. Ocular involvement can occur in both forms, but it is more frequently observed in systemic mastocytosis. The uncontrolled growth of mast cells in systemic mastocytosis is linked to mutations in the KIT gene, particularly the D816V mutation.
Symptoms and Eye Manifestations
Ocular mastocytosis presents with symptoms due to the inflammatory response triggered by mast cell mediators. Patients commonly experience itching, redness, swelling, a burning sensation, excessive tearing, and sensitivity to light. These symptoms can range from occasional to chronic and may affect one or both eyes.
Chronic inflammation of the conjunctiva, known as conjunctivitis, is a frequent manifestation. Inflammation can also affect the sclera, the white outer layer of the eyeball, leading to conditions like scleritis or episcleritis. Additionally, uveitis, an inflammation of the uvea—the middle layer of the eye that includes the iris, ciliary body, and choroid—can occur. In rarer instances, mast cell infiltration can lead to orbital involvement, causing swelling behind the eye or in the eyelids, resulting in exophthalmos, or bulging of the eye. Persistent or severe inflammation can cause blurred vision and, in some cases, significant visual impairment.
Diagnosing Ocular Mastocytosis
Diagnosing mastocytosis when it affects the eyes begins with a thorough eye examination by an ophthalmologist. The specialist looks for signs of inflammation and mast cell accumulation within ocular tissues. This initial examination helps to identify the extent of eye involvement.
Further diagnostic steps include blood tests to measure serum tryptase levels, which can be elevated due to mast cell activation. If a suspicious lesion or abnormal tissue is observed, a biopsy of ocular tissue, such as the conjunctiva, may be performed. This biopsy allows for histological examination to confirm the presence and infiltration of mast cells. Genetic testing for the KIT D816V mutation is also relevant, as it is a common marker for systemic mastocytosis and helps confirm systemic involvement alongside ocular symptoms. Collaboration with other medical specialists, such as allergists or hematologists, is necessary to establish a comprehensive systemic diagnosis.
Treatment Approaches
Treatment for ocular mastocytosis focuses on managing symptoms, reducing inflammation, and preventing potential complications. Topical medications are used as a first line of defense. These include antihistamine eye drops for itching and redness, and mast cell stabilizer eye drops, such as cromolyn sodium, which prevent mast cells from releasing inflammatory chemicals. Corticosteroid eye drops may also be prescribed for acute inflammation to quickly reduce swelling and discomfort.
For more severe cases or when systemic mastocytosis affects the eyes, oral medications may be necessary. Oral antihistamines and oral corticosteroids can help control widespread symptoms. For aggressive systemic mastocytosis with ocular manifestations, systemic mast cell-targeting therapies, such as tyrosine kinase inhibitors like midostaurin, may be considered to address disease progression. Supportive care, like applying cold compresses and avoiding triggers such as pollen, animal dander, or mold spores, can also help manage symptoms and prevent flare-ups. Ongoing monitoring by an ophthalmologist and other specialists is important to adjust treatment plans as needed and manage any long-term effects on vision.