The correct answer is C.
Explanation:
This patient’s presentation is most consistent with primary acquired melanosis (PAM), a flat, unilateral, patchy golden-brown conjunctival pigmentation seen most often in fair-skinned middle-aged or older adults. The key differential for conjunctival pigmented lesions includes conjunctival nevus, which usually appears earlier in life, is often well circumscribed and cystic, and has low malignant potential; complexion-associated/racial melanosis, which is typically bilateral and occurs in darker-pigmented individuals; and conjunctival melanoma, which more often appears as a raised or nodular vascular lesion and carries metastatic risk. PAM may wax and wane clinically, but because PAM with atypia can transform into melanoma and atypia requires histopathologic diagnosis, management is guided largely by lesion extent and suspicious features: lesions involving less than 1–2 clock hours can often be observed with serial slit-lamp photography, whereas lesions involving more than 2 clock hours should generally be excised, with cryotherapy applied to the margins. In this case, the lesion involves approximately 3–4 clock hours at the limbus with minimal corneal extension, making surgical excision with cryotherapy the preferred initial approach (C). In a retrospective review by Shields et al., PAM without atypia or with mild atypia showed 0% progression to melanoma, whereas PAM with severe atypia progressed to melanoma in 13%, and the greater the extent of PAM in clock hours, the greater the risk of transformation. Observation and reassurance is inappropriate because this is a new, unilateral, changing lesion in an older Caucasian patient with more than 2 clock hours of involvement (A). Topical mitomycin C alone is not preferred as primary therapy because topical chemotherapy is generally reserved for diffuse, residual, or postoperative disease rather than replacing excisional biopsy when diagnosis and margin treatment are needed (B). Finally, PET-CT is not indicated initially because there is no confirmed invasive conjunctival melanoma or evidence of metastatic disease requiring systemic staging (D).
Source:
https://www.aao.org/education/1-minute-video/pearls-recognizing-treating-conjunctival-pigmented
https://www.aao.org/eyenet/article/conjunctival-pigmented-lesions-diagnosis-managemen#Surgery
https://www.willseye.org/disease_condition/conjunctival-primary-acquired-melanosis/
Shields JA, Shields CL, Mashayekhi A, Marr BP, Benavides R, Thangappan A, Phan L, Eagle RC Jr. Primary acquired melanosis of the conjunctiva: experience with 311 eyes. Trans Am Ophthalmol Soc. 2007;105:61-71; discussion 71-2. PMID: 18427595; PMCID: PMC2258121.
