144 Clinical epidemiology of Masson tumor

Abstract

Intravascular papillary endothelial hyperplasia (IPEH), also known as Masson tumor–a rare, benign vascular lesion typically presenting in the skin as a subcutaneous nodule – may be clinically mistaken for other neoplasms such as hemangiomas and lipomas. IPEH is classically categorized into three types:1) pure type arising in dilated endovascular spaces; 2) mixed type developing from preexisting vascular abnormalities; 3) extravascular type. While the prognosis of IPEH is excellent, it must be differentiated from malignant tumors such as angiosarcomas, which may require intensive treatments. Because the literature on IPEH is limited, we sought to characterize clinical and pathological features of IPEH. Subjects were identified using the Mass General Brigham (MGB) Research Patient Data Registry and included individuals with pathologically proven diagnosis of IPEH from 1/1980 to 8/2021 at Massachusetts General Hospital, Brigham and Women’s Hospital (BWH), and the BWH Faulkner Hospital. Demographic information, clinical documentation, and pathology reports were reviewed for data extraction. 261 individuals were diagnosed with IPEH, with the majority being women (60%) and white (74%). The average age at diagnosis was 53 years old [4-98 years old]. The most frequently involved anatomic sites were the upper (29%) and lower (24%) extremities. Common initial clinical diagnoses of lesions were cysts, hemangiomas, and lipomas. The pure subtype of IPEH was the most common (50%), followed by the mixed (46%) and extravascular subtypes (4%). Extravascular IPEH occurred more frequently in women (5%) compared to men (1%). We found that most clinicians’ initial impressions prior to biopsy did not include the final diagnosis of IPEH -- often using vague terms such as “soft tissue mass” -- indicating a potential need for greater awareness of this condition. Given the differential diagnosis of IPEH often includes conditions such as melanoma or angiosarcoma, clinicopathologic correlation is of utmost importance for this uncommon vascular lesion.