Nondiagnostic conjunctival map biopsies for sebaceous carcinoma.

OBJECTIVE: To compare the prevalence of nondiagnostic conjunctival map biopsies in patients with extensive pagetoid sebaceous carcinoma (defined as involvement of 3 or 4 quadrants of the ocular surface) and in patients without extensive pagetoid tumor (defined as involvement of 1 or 2 quadrants of the ocular surface).
METHODS: Retrospective medical record and pathologic specimen review of 20 patients treated for sebaceous carcinoma at a tertiary care center. Biopsies with artifactual loss of or damage to the epithelium were categorized as nondiagnostic.
RESULTS: One hundred forty-four map biopsies were reviewed, an average of 7.2 (standard deviation [SD], 4.4) biopsies per patient. Sixteen patients had extensive pagetoid tumor, 4 did not. Fifteen percent of biopsies were nondiagnostic. The frequency of nondiagnostic biopsies in patients with and without extensive pagetoid tumor was 37% and 10%, respectively. The odds ratio of nondiagnostic biopsy in the setting of extensive pagetoid tumor was 5.9 (95% confidence interval, 2.3-15.6; P = .004). Six of the sixteen patients (38%) without extensive pagetoid tumor had at least 1 nondiagnostic biopsy, with an average of 1.8 (SD, 1.6) nondiagnostic biopsies per patient (22% of biopsies). Two of the 4 patients (50%) with extensive pagetoid tumor had at least 1 nondiagnostic biopsy, with an average of 5.5 (SD, 3.5) nondiagnostic biopsies per patient (57% of biopsies).
CONCLUSIONS: Nondiagnostic, de-epithelialized conjunctival map biopsies are more common in patients with extensive pagetoid tumor than in those with limited or no pagetoid tumor. Artifactual epithelial loss may result from disruption of epithelial adhesion to the basement membrane by infiltrating tumor cells.