We retrospectively reviewed 107 consecutive cases of radial scar and complex sclerosing lesions in a 54 month period seeking vascular lesions using archival H&E stained 5 μm thick sections. Eight showed vascular abnormalities, five being false aneurysms which were limited to 62 lesions>10 mm diameter; no false aneurysm was found in 45 radial scars ≤10 mm. All cases displayed arterial lesions, but two also showed associated venous fibrosis. Traumatic false aneurysms with loss or severe thinning of the media and intimal, medial or extravascular spindle cell proliferation were found in the arteries of five cases with histological evidence of local reaction to previous fine‐needle aspirational biopsy and clinical documentation of aspiration 18 to 121 days before. The diameters of the false aneurysms correlated with the original widths of the arteries. The other lesions with mature intimal fibrosis in arteries or veins lacked such local post‐aspiration expansile reactive changes, or a history of fine needle aspiration. We conclude that traumatic false aneurysms found in complex sclerosing lesions seem to be iatrogenic, resulting from fine needle aspiration. Mature fibrosis in veins or arteries are probably unrelat