Pinguecula

Pinguecula (derived from Latin word pinguis, which means fat) represents an area of bulbar conjunctival thickening adjoining limbus in the palpebral fissure area. Pinguecula are less transparent than normal conjunctiva and often have a fatty appearance. They are usually bilateral, triangular, elevated, white to yellow in colour, horizontally oriented, and are located nasally much more often than temporally. They may also present on both the nasal and temporal conjunctiva in the eyes of some patients. Pinguecula does not cross the limbus, and current information suggests that pinguecula does not progress to pterygium and that the two are distinct disorders.

Pinguecula are associated with a two to three fold increase in incidence of age-related macular degeneration, possibly through a common light exposure effect (Pham TQ et al).

Degenerations of the conjunctiva are common conditions that, in most cases, have relatively little effect on ocular function and vision. These conditions increase in prevalence with increasing age as a result of past inflammation, of long-term toxic effects of environmental exposure, or of ageing itself. Conjunctival degenerations may be associated with chronic irritation, dryness, or previous history of trauma.

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Dushku N, Hatcher SL, Albert DM, Reid TW. p53 expression and relation to human papillomavirus infection in pingueculae, pterygia and limbal tumours. Arch Ophthalmol. 1999; 117: 1593- 1599.

Pham TQ, Wang JT, Rochtchina E, Mitchell P. Pterygium/pinguecula and the five-year incidence of age related maculopathy. Am J Ophthalmol. 2005; 139: 536- 537. 

Pinguecula are usually asymptomatic.

Pinguecula are associated only rarely with any symptoms other than a minimal cosmetic effect.

Ocular (eye) symptoms include:

  • Foreign body sensation.
  • Watering.
  • Burning.
  • Itching.
  • Mild pain.
  • Redness.

Pinguecula remains relatively free from congestion and becomes conspicuous when the eye is inflamed. They may become red with surface keratinisation. When inflamed, the diagnosis of pingueculitis is given.

The causes of pinguecula are not known with certainty.

Pinguecula are more likely in males, welders and older individuals living in warmer climates. Pinguecula are more common than pterygium.

Evidence suggests its association with:

  • Increasing age: Pinguecula are seen in most of the patients by 70- 80 years of age.
  • Ultraviolet light exposure: Chronic sunlight exposure (actinic damage due to both ultraviolet A and B light) is associated with outdoor work and equatorial residence. Association with light exposure is found in welders, who have higher rate of pinguecula as compared to non-welders. Possibly, predominantly nasal location is related to reflection of light from the nose onto the nasal conjunctiva. The effect of ultraviolet light may be mediated by mutations in gene p53.
  • Gaucher’s disease (inherited lipid storage disease): Pigmented, brown, triangular pinguecula may appear during second decade of Gaucher’s disease. Biopsy from the lesions shows Gaucher cells. Patients with Gaucher’s disease may show associated congenital oculomotor apraxia and white retinal infiltrates. There may be corneal opacities in posterior two-thirds of the stroma. The genetic defect in Gaucher’s disease lies on chromosome 1q21.

The diagnosis is usually clinical and may require slit-lamp biomicroscopy.

Clinical features:

  • Pinguecula are located in the anterior bulbar conjunctiva adjacent to the limbus.
  • Pinguecula are located in the inter-palpebral zone, usually more nasally than temporally.
  • Usually, there is no corneal involvement. However, there may be punctate epithelial erosions or dellen (thinning of adjacent peripheral part of cornea due to drying).
  • A grading system showed no significant difference in nasal versus temporal size.
  • Pinguecula are yellowish-white sub-epithelial deposits with possible calcifications.
  • Occasionally pinguecula may become inflamed (called pingueculitis) and irritated due to surface drying. The lesion may become highly vascularised and injected.

Histopathology:

Pinguecula are characterised by elstotic degeneration of the collagen with hyalinisation of the conjunctival stroma, collection of basophilic elastotic fibers, and granular deposits.

  • The sub-epithelial tissue shows senile elastosis (basophilic degeneration) and irregular, dense sub-epithelial concretions. The elastotic material stains positively for elastin but is not sensitive to elastase (elastotic degeneration).
  • The elastotic material is positive for elastin, microfibrillar protein, and amyloid P. These components never normally co-localise.

The control of elastogenesis is seriously defective so that elastic fibers are abnormal in biochemical organisation. Normal assembly of elastic fibers is prevented due to marked reduction of elastic microfibrils. Limbal epithelial cell mutations at gene p53, probably due to ultraviolet irradiation, may be an early event in the development of pinguecula. The sub-epithelial dense concretions stain positively for lysozyme. Pinguecula may calcify with time.

Electron microscopy:

Under electron microscopy, the granular material consists of hollow- centered microfibrils, which are elastic fiber precursors. The material is overproduced by numerous fibroblasts that are thought to be actinically activated by sunlight exposure.

Immunoassay:

Immunoassay suggests an abnormal epidermal differentiation due to a decline in the expression of Pax6, K19 keratin, and MUC5AC (a protein coding gene), but an associated increase in K10 and K14 keratin. There is also active proliferation of the squamous cells, as evidenced by positive expression of Ki67, P63, and K16 keratin.

Pinguecula may become inflamed due to dryness and irritation, resulting in so-called pingueculitis. The most common causes of such inflammation are:

  • Mechanical irritation: Irritation by the edge of a contact lens is a frequent cause.
  • Ocular surface disease.

The epithelium overlying a pinguecula can vary from atrophic and thinned to hyperplastic and thickened. Pinguecula are unlikely to undergo malignant conversion. However, a lesion that looks atypical should be approached with suspicion. Actinic keratosis, dysplastic changes, and even carcinoma can arise within the epithelium overlying a pinguecula.

 

Pinguecula may be differentiated from:

  • Limbal dermoid.
  • Conjunctival intraepithelial neoplasia.
  • Conjunctival tumour like naevus, melanoma or papilloma. 

Management should be carried out under medical supervision.

Management includes:

Medical therapy:

  • Elimination of the causal factor.
  • Artificial tears: Increased lubrication with artificial tears.
  • Topical corticosteroids: Short course (to avoid adverse side-effects) of topical steroids may be given when inflammation is significant.
  • Non-steroidal anti-inflammatory drugs (NSAIDs): Non-steroidal anti-inflammatory drugs (NSAIDs) may be used in cases of associated inflammation.

Surgical therapy:

  • Simple excision: Chronically inflamed or cosmetically unsatisfactory pingueculae rarely warrant simple excision.
  • Laser photocoagulation: Laser photocoagulation may be used to remove pinguecula.

Steroids or surgical excision are discouraged unless there is chronic irritation or interference with the use of contact lens.

 

Prognosis:

Pinguecula may grow slowly over time but are associated with minimal ocular morbidity (a diseased state).

Potential possible complications of pinguecula are:

  • Pinguecula can slowly enlarge to become inflamed and irritating (Pingueculitis).
  • Restriction of extra-ocular movement.
  • Astigmatism.
  • Dellen.
  • Dysplastic changes and even carcinoma can arise within the epithelium overlying a pinguecula.
  • May progress to chronic actinic keratopathy.

 

Prevention may include avoidance of ultraviolet-light exposure and use of ultraviolet-blocking spectacles.

  • PUBLISHED DATE : May 12, 2016
  • PUBLISHED BY : Zahid
  • CREATED / VALIDATED BY : Dr. S. C. Gupta
  • LAST UPDATED ON : May 12, 2016

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