The utility and challenges of histopathologic evaluation in the diagnosis of nonmalignant skin ulcers

Histopathologic evaluation of cutaneous ulcers is indicated when the clinical diagnosis is unclear or when ulcers have not responded to standard of care. Many nonmalignant skin ulcers lack specific histologic findings on biopsy and pose a diagnostic challenge. While the usefulness of skin biopsies to diagnose underlying malignancy in ulcerated lesions has been demonstrated in previous studies, their utility in the diagnosis of ulcers of other etiologies has not been reported. We conducted a retrospective study of 45 nonmalignant ulcer biopsies in a 3-year period to compare the histologic diagnosis with the final diagnosis. Additionally, we assessed the diagnostic concordance among three blinded dermatopathologists when reviewing these cases. The leading histologic diagnosis from each of the three observers agreed with the final clinical diagnosis, on average, for 29.6% of the cases (average pairwise kappa = 0.15). Inflammatory ulcers had the lowest concordance between the observers and final diagnosis with an average of 26.0% of cases (average pairwise kappa = 0.06). The observers agreed with each other for 35.6% of the cases (Fleiss' kappa = 0.32). The highest agreement among observers was in the vascular/vasculopathic category (50%, Fleiss' kappa = 0.44). Our results indicate that skin biopsies alone are useful in the evaluation of nonmalignant ulcers to rule out other conditions (e.g. neoplasm) but frequently not sufficient to establish a definitive diagnosis. Additional clinicopathologic correlation is necessary in the final assessment of nonmalignant ulcers to determine the diagnosis. Future research endeavors should explore alternative approaches to more efficiently diagnose nonmalignant skin ulcers.