The Value of Preoperative Imaging and Intraoperative Histopathology in Morton’s Neuroma

CATEGORY: Lesser Toes INTRODUCTION/PURPOSE: Morton’s neuroma is an interdigital abnormality of the nerve between the lesser metatarsal heads, most commonly between the third and fourth metatarsals. Recent studies have demonstrated that clinical diagnosis is highly correlated with intraoperative and histopathological diagnosis, and other studies have questioned the cost-effectiveness of intraoperative histopathology of an excised neuroma to confirm the diagnosis or rule out occult malignancy. The purpose of this study is to determine the utility of preoperative imaging and intraoperative histology in making an accurate diagnosis, guiding treatment decisions, and altering clinical outcomes. We also investigate the potential savings of a more streamlined diagnostic algorithm. METHODS: A retrospective review was performed on all patients that underwent surgical resection of a suspected Morton’s neuroma with 4 fellowship-trained foot & ankle surgeons from 2007 to 2017. Patients were excluded from the study if the pathology report was not available for review. In all cases, chart review was undertaken to determine the method of initial diagnosis. Diagnoses were made either by the clinical examination of the operating surgeon and/or by the results of preoperative magnetic resonance imaging (MRI) and/or ultrasound. Operative reports were examined to determine if excised specimens were sent for histopathological analysis. All pathology reports were reviewed to determine the final diagnosis, considered the “gold standard”. Postoperative chart notes were reviewed to determine if any treatment regimen was altered based on the pathology report revealing an alternate diagnosis other than Morton’s neuroma. RESULTS: Three-hundred twenty-seven patients with 354 clinically suspected neuromas were identified through retrospective chart review, and 287 patients with 313 clinically suspected neuromas met inclusion criteria. Of the 313 suspected neuromas with accompanying pathology reports, 309 (98.7%) were confirmed Morton’s neuroma upon histopathological examination. For no patient did the results of the pathology report alter the postoperative treatment course. Preoperative imaging results were available for 179/313 (57.2%) suspected neuromas, with MRI and ultrasound being used to preoperatively image 121 and 71 suspected neuromas, respectively, including 13 with both. The total estimated cost of pathological analysis at our institution for the 287 patients in our study was $131,733, and the potential total combined cost savings by eliminating preoperative imaging and intraoperative histopathology in our cohort totals $266,632. CONCLUSION: Our study demonstrates that the diagnosis of Morton’s neuroma can be made clinically with extreme accuracy and positive predictive value, calling into question the utility and costs of other imaging modalities and intraoperative sampling for histopathologic diagnosis. Furthermore, in only 4 cases did the pathologic diagnosis disagree with the diagnosis based on clinical exam and imaging, and in none did the pathologic diagnosis alter the course of treatment. Without more clear evidence that these modalities increase diagnostic accuracy, change the course of treatment, or improve patient care, we recommend that preoperative advanced imaging and histopathological examination not be routinely performed.