Orbital Tumor

Pathophysiology

Inflammatory lesions (61%)

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  Inflammatory lesions can often masquerade as orbital tumors and include diagnoses such as preseptal and orbital cellulitis, conjunctivitis, uveitis, and episcleritis.

Orbital cystic lesions (10%)

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  Orbital dermoid cysts are the most common (37%).

  
  
  
  
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    This is a congenital lesion that forms from epithelial cells that are entrapped during embryogenesis beneath the surface epithelium, often near bony sutures.

  
  
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  Mucoceles usually arise from frontal or ethmoid sinuses owing to chronic inflammation that invades the orbit.

  
  
  
  
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    If pus filled, this is called mucopyocele.

    
    
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    If children, may be from cystic fibrosis.

Orbital vascular and hemorrhagic lesions (5%)

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  Cavernous hemangioma:

  
  
  
  
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    Most common benign adult vascular orbital tumor. A congenital abnormality resulting in slow growth of endothelial cell-lined vessels surrounded by a fibrous capsule. Usually become apparent during middle age and may not exhibit swelling or external signs (Figure 29.1).

  
  
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  Arteriovenous fistulas:

  
  
  
  
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    Occur from abnormal communications between previously normal arteries and veins. 75% occur owing to trauma, often in younger patients. 25% can occur spontaneously and are more likely in the elderly.

    
    
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    Two forms:

    
    
    
    
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      Carotid cavernous fistulas are considered high flow (Figure 29.2).

      
      
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      Dural cavernous fistulas are considered low flow and often caused by systemic hypertension and atherosclerosis.

Orbital peripheral nerve tumors/other neural tumors

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  Orbital neurofibroma (Figure 29.3):

  
  
  
  
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    Benign peripheral nerve tumor

    
    
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    Often presents with proptosis, globe displacement, diplopia

    
    
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    May be localized or plexiform. The plexiform type is always associated with Neurofibromatosis Type 1 (NF-1)

Lacrimal gland primary epithelial tumors

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  Lacrimal gland duct epithelial cyst (dacryops):

  
  
  
  
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    Inclusion cyst develops secondary to occlusion of one or more of the ducts that drains from the lacrimal gland to the conjunctival fornix.

    
    
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    Usually arises from the palpebral lobe, may be unilateral or bilateral, will often be painless and nontender.

Orbital histiocytic tumors/pseudotumors

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  Langerhans cell histiocytosis (eosinophilic granuloma and formerly known as Histiocytosis X) (Figure 29.4):

  
  
  
  
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    Pathologic Langerhans cells proliferate, often with inflammatory cells (primarily eosinophils) causing local, often bony, destruction.

    
    
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    Typically occur in the 1st decade of life and often present as swelling in the superotemporal aspect of the orbit and often accompanied by pain, redness, tenderness, rarely bilateral.

Neoplasms

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  Primary orbital neoplasms:

  
  
  
  
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    Lymphoma is the most common in the orbit (Figure 29.5).

    
    
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    Malignant proliferation of abnormal lymphocytic cells (often B-cell origin) and include the following:

    
    
    
    
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      Extranodal marginal cell lymphoma (EMZL) a.k.a. mucosal associated lymphoid tissues (MALT)

      
      
      
      
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        Follicular lymphoma

        
        
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        Diffuse large B-cell lymphoma (DLBCL)

        
        
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        Mantle cell lymphoma (MCL)

    
    
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    Most common presenting symptoms include swelling (48%), mass (49%), and proptosis (37%).

    
    
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    Primary intraorbital lymphomas are often associated with autoimmune disease.

  
  
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  Orbital metastatic neoplasms:

  
  
  
  
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    The most frequent adult metastatic cancers include breast, lung, renal cell, thyroid, and prostate cancer.