A medial canthus cyst is a growth located at the inner corner of the eye, near the nose. This area, the medial canthus, contains various tissues and structures, including tear ducts and glands. A cyst here is typically a sac filled with fluid, air, or semi-solid material, forming due to blockages, developmental issues, or other factors.
Types and Origins of Medial Canthus Cysts
Several types of cysts can develop in the medial canthus region, each stemming from different underlying causes.
Dermoid cysts are developmental formations originating from ectodermal elements like skin cells and hair follicles. These elements become trapped along embryonic fusion lines during early development. Often present from birth, these cysts are common orbital tumors in children.
Epidermal inclusion cysts, also called epidermoid cysts, contain keratinized squamous epithelium and lipids. They can be congenital or acquired, often developing after trauma or surgery embeds surface epidermal tissue beneath the skin.
Dacryocystoceles, also known as lacrimal sac mucoceles, arise when the nasolacrimal duct becomes obstructed at both ends. This leads to mucoid fluid accumulation within the lacrimal sac. These are typically congenital and observed in newborns.
Mucoceles can also originate from paranasal sinuses, such as the ethmoidal sinuses, when drainage pathways become blocked. This causes mucus to build up. Adult nasolacrimal sac mucoceles are often linked to chronic acquired nasolacrimal duct obstruction, leading to distension of the lacrimal sac with mucopurulent material. Hidrocystomas, which can be apocrine or eccrine, result from blocked sweat ducts in the eyelid skin. Though less common in the medial canthus, apocrine hidrocystomas can cause functional issues based on their size and proximity to other structures.
Recognizing a Medial Canthus Cyst
Identifying a medial canthus cyst often begins with observing a noticeable lump or swelling in the inner corner of the eye. The cyst may feel soft, firm, or movable, depending on its contents and depth. Its appearance can vary from skin-colored to pearly, or even bluish-gray, particularly for dacryocystoceles. Cysts range in size from a small nodule to a larger mass that becomes more prominent over time.
Many medial canthus cysts are asymptomatic, causing no discomfort or problems unless they grow larger or become infected. When symptoms occur, they might include localized swelling and tenderness around the cyst. If the cyst affects the lacrimal drainage system, individuals may experience excessive tearing, known as epiphora.
Redness in the overlying skin can signal inflammation or infection. Specific cyst types may also present unique signs; for instance, epidermal inclusion cysts might have a central pore. In infants, dacryocystoceles can sometimes lead to nasal obstruction due to their internal extension into the nasal cavity. A cyst growing large enough to exert pressure on the eyeball or surrounding structures could lead to visual disturbances.
Diagnosis and Management Options
Diagnosing a medial canthus cyst typically begins with a physical examination by a healthcare professional. This involves visual inspection and gentle palpation to assess the cyst’s size, consistency, mobility, and any signs of inflammation. To understand the cyst’s characteristics and its relationship to surrounding tissues, various imaging techniques may be employed. Ultrasound can be useful for diagnosing dacryocystoceles, even before birth or shortly after.
Computed tomography (CT) scans provide detailed cross-sectional images, helping determine the cyst’s size, contents, and bone involvement. This is important for dermoid cysts and mucoceles. Magnetic resonance imaging (MRI) offers excellent soft tissue contrast, allowing precise visualization of the cyst’s extent and its proximity to delicate orbital and nasal structures.
If tear drainage system involvement is suspected, a dacryocystography may be performed. This involves injecting contrast dye into the tear ducts to visualize their patency and any obstructions. When malignancy is a concern or a definitive diagnosis is needed, a biopsy is performed to confirm the cyst type. This involves removing a tissue sample for histopathological analysis.
Management strategies for medial canthus cysts vary based on the cyst type, size, symptoms, and potential complications. For small, asymptomatic cysts causing no functional issues, observation may be recommended. Surgical removal is the primary treatment for cysts that are symptomatic, growing, cosmetically bothersome, or when diagnostic uncertainty exists. Complete surgical excision is often the preferred approach for dermoid cysts, requiring careful dissection to protect the adjacent lacrimal drainage system. Temporary silicone intubation of the tear ducts can help safeguard them during such procedures. Epidermal inclusion cysts are also typically managed with surgical excision.
For dacryocystoceles, conservative treatments like gentle massage may be attempted. If these are unsuccessful, procedures such as probing and irrigation of the nasolacrimal duct or endoscopic resection might be necessary. Mucoceles, especially those from the lacrimal sac, often require surgical interventions like dacryocystorhinostomy (a procedure to create a new tear drainage pathway) or marsupialization (creating an opening to drain the cyst). For infection or inflammation, antibiotics and warm compresses may be prescribed.
If left unaddressed, medial canthus cysts can lead to complications. These include recurrent infections, such as dacryocystitis (inflammation of the lacrimal sac) or cellulitis (a bacterial skin infection). Larger cysts can also cause visual impairment, proptosis (forward displacement of the eyeball), or strabismus (misalignment of the eyes) by placing pressure on the globe. Although rare, some cysts, like dermoid cysts, have a small risk of malignant transformation.