Abstract
Purpose :
PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry (IHC) is a valuable diagnostic tool and prognostic marker in the evaluation of cutaneous melanomas. Recently, strong nuclear PRAME IHC labeling was found to help distinguish malignant from benign conjunctival melanocytic lesions (CMLs) (PMIDs: 20805128, 34268800, 34089198). To corroborate these findings, we performed a retrospective study of PRAME IHC staining patterns in previously biopsied CMLs at our institution.
Methods :
CMLs were obtained from 16 patients who underwent biopsy of conjunctival lesions. IHC was performed to evaluate for melanocytic differentiation (MelanA, HMB-45, or SOX-10) and nuclear PRAME expression. Patient demographics, lesion characteristics, and PRAME status by IHC were included in the retrospective cohort analysis.
Results :
The cohort of 16 patients included 11 females and 5 males, with an average age of 48.8 years (range 3 to 86 years). At the time of the study, all patients were alive and without evidence of metastatic disease. CML diagnoses were categorized as either benign melanosis (5/16), benign nevus (8/16), or malignant melanoma (3/16). Nuclear PRAME immunolabeling was detected in 2 of 3 patients with malignant melanoma (66%) and 0 of 13 histologically benign CMLs. Of the 3 malignant melanoma cases, PRAME nuclear expression was not detected by IHC on both the biopsy and subsequent excision of an invasive melanoma that involved the superior nasal and temporal conjunctiva of an 86-year-old male, harboring BRAF V600E, MSH2 R406X, and TERT promoter mutations.
Conclusions :
Our current study is consistent with prior reports, which contend that PRAME IHC can be used as an ancillary marker to help distinguish malignant versus benign CMLs. However, our analysis revealed one patient with a PRAME-negative invasive conjunctival melanoma. Although the findings are promising, additional large-scale studies are needed to determine the specificity and sensitivity of PRAME IHC in the evaluation of suspected conjunctival melanomas.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.