Pinguecula Appearance: Not Always a Raised Yellow Bump
Pinguecula can present as either a raised yellowish bump OR as a flat yellowish to brownish spot on the conjunctiva—it is not always elevated. 1, 2, 3
Clinical Presentation Spectrum
Pinguecula demonstrates variable morphology that clinicians must recognize:
- Classic presentation: A small, raised conjunctival nodule at the temporal or nasal limbus with yellowish coloration 1
- Elevated lesions: Can appear as a prominent yellowish mass with measurable height (documented cases show elevations of 740 µm or more) 2
- Flat presentations: May manifest as yellowish or brownish spots without significant elevation 3
- Color variations: Ranges from pale yellow to brownish, depending on the degree of degeneration and chronicity 3
Histologic Basis for Appearance
The appearance reflects the underlying pathology:
- Composition: Benign peribulbar lesions composed of degenerated basophilic subepithelial tissue 3
- Location: Typically found at the nasal or temporal limbus, adjacent to the cornea 1, 3
- Associated findings: May show conjunctival injection, particularly when symptomatic 2
Critical Differential Diagnosis
A yellowish or brownish spot on the conjunctiva requires careful evaluation to exclude malignancy:
- Conjunctival melanoma: Presents as painless, flat or nodular brown lesions on bulbar or palpebral conjunctiva—can be flat initially 4, 5
- Sebaceous carcinoma: May appear as yellowish discoloration of the tarsal plate or subconjunctival multilobulated yellow mass 4, 6
- Warning signs requiring urgent evaluation: Enlargement of lesion, development of blood vessels, thickening, or recurrence in the same location (especially in elderly patients) 5, 6
Clinical Assessment Approach
When evaluating yellowish/brownish conjunctival lesions:
- Slit-lamp biomicroscopy: Essential to evaluate location, depth, elevation, and associated findings 5
- Document characteristics: Note whether lesion is flat versus elevated, color intensity, presence of vessels, and any associated inflammation 2
- Consider biopsy: For atypical features, recurrent lesions in same location, or elderly patients with history of multiple excisions 6
Common Pitfall
Do not assume all yellowish conjunctival lesions are benign pinguecula. The flat, pigmented presentation can mimic early malignancy, particularly melanoma or sebaceous carcinoma, which have devastating consequences if diagnosis is delayed 4, 5, 6. Any lesion showing growth, vascularization, or atypical features warrants ophthalmologic referral and possible biopsy.