Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Saturday, June 24, 2006

What is a pinguecula?

Definition: A pinguecula is a vascularized growth of tissue, often bilateral, situated at the nasal or temporal limbus.
Incidence/Prevalence: Pingueculae occur more commonly in older patients but certainly occur frequently in individuals with prolonged exposure to sunlight at a younger age.
Etiology: Related to ultraviolet light exposure. More common in those living in sunny areas.
Clinical Findings: Wing shaped elevated grey vascular lesions that appear in the interpalpebral fissure (solar related) usually at 3 and 9 o’clock (see clinical photo below arrows labeled 1). They may be yellow particularly if there is accompanying spheroidal degeneration. In the clinical photo there are clearly dilated tortuous vessels (labeled 2).
Histopathology: There are 3 consistent characteristic findings:
1. basophilic degeneration of collagen (solar elastosis). These changes manifest as a nodule of fragmented basophilic degeneration (unlabeled arrows in the low mag photomicrograph below and arrow #1 in hi mag photomicrograph). Also called elastotic degeneration because the degenerated collagen will stain black with the Verhoeff-van Gieson stain and give the appearance of elastic fibers. Controversy arises as some believe pre-existing elastic fibers are involved while others point out that elastase does not eliminate the staining. There also may be a fibrillar degeneration of collagen that is not basophilic.

2. chronic inflammation in the substantia propria. The inflammation is usually mediated by lymphocytes and mononuclear inflammatory cells (arrow #2 in high magnification).
3. Enhanced vascularization (arrow #2 at low mag and arrow number 3 at high magnification). None of these findings are specific but they are virtually immutable. In addition the overlying epithelium is said to be thinned, but alas may be normal, hyperplastic or dysplastic (in which case the main diagnosis is dysplasia). There may be focal keratinization.
Treatment: Pinguecula are usually not removed unless there is concern for dysplasia, cosmesis or prolonged bouts of inflammation. However, with encroachment on the cornea, pinguecula become pterygia and may produce visual symptoms.

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