A prospective, single-center study was performed to evaluate the diagnostic accuracy of a skin-specific, handheld in vivo confocal microscope (IVCM) for detecting malignant conjunctival and eyelid margin tumors.
Study design
The investigators included 278 consecutive patients and examined a total of 295 lesions. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of IVCM was compared to corresponding values obtained from a slit-lamp examination.
Outcomes
Of the 166 eyelid margin and 129 conjunctival tumors examined, 155 were excised for histopathology based on suspicious slit lamp and/or IVCM findings. The authors found that handheld IVCM was more sensitive (98% vs. 92%) and specific (74% vs. 46%) than clinical slit lamp examination for identifying malignant eyelid tumors.
For conjunctival tumors, IVCM was more sensitive (100% vs. 88%) but less specific (78% vs. 88%) than slit lamp exam. A significant cause of IVCM’s reduced conjunctival specificity was due to device’s inability to clearly differentiate hyperreflective Langerhans cells from malignant melanocytes. This led to excision of several benign conjunctival lesions.
The remaining 140 lesions had benign characteristics on both IVCM and slit lamp exam. All 140 were deemed benign upon reexamination at 1 year with both techniques, and were thus reported as true negatives.
The PPV for all subtypes of eyelid malignancy was 86% with IVCM and 72% with clinical exam. The NPVs were 97% and 78%, respectively. For all types of conjunctival malignancies, the PPV of IVCM and clinical exam were 77% and 84%, respectively, and NPVs were 100% and 90%.
Limitations
Not all lesions had histopathology to determine final diagnosis. However, lesions that did not get excised and biopsied were all chronic and remained unchanged after 1 year.
Clinical Significance
The IVCM technique appears to provide a promising non-invasive "optical biopsy" option for evaluation of suspect eye-area lesions, which are currently biopsied in many cases. This would be particularly beneficial in patients with surface disease and glaucoma, in whom removing conjunctival tissue for histopathology carries a higher risk of complications. Because the same area can be imaged repeatedly over time with IVCM, this may be a useful tool for studying lesions following treatment and monitoring for recurrence.