A 48-year-old fair-skinned woman has a unilateral, flat, patchy, non-elevated area of brown pigmentation on the bulbar conjunctiva of one eye, present for several years and slowly enlarging. There is no nodularity or feeder vessel. Biopsy is planned. Which histological finding best predicts progression to conjunctival melanoma?
- A Melanin pigment within the epithelium
- B Presence of cytologic atypia in the basilar melanocytes ✓
- C Nests of naevus cells at the epithelial stromal junction
- D Chronic inflammatory infiltrate in the substantia propria
Correct answer: B. Presence of cytologic atypia in the basilar melanocytes
Explanation
Primary acquired melanosis (PAM) is a unilateral, flat, patchy pigmentation of the bulbar conjunctiva in middle-aged fair-skinned individuals. Its malignant potential depends entirely on the presence of cytologic atypia in the melanocytes; PAM with atypia progresses to invasive melanoma in roughly half of cases, while PAM without atypia is essentially benign. Pigment itself is merely melanin and carries no prognostic weight, which eliminates option A.
Reference: Yanoff and Duker, Ophthalmology, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.