Neoplastic and Malignant Lesions Involving or Arising in a Radial Scar: A Clinicopathologic Analysis of 17 Cases.

Seventeen radial scars (RSs) containing or secondarily involved by lobular neoplasia (n = 8), ductal carcinoma in situ (DCIS) (n = 3), and invasive carcinoma (n = 6) are described. The patients ranged in age from 44 to 84 years with an average age of 58. Nine lesions presented as a palpable mass; three of the palpable masses were due to a variety of benign lesions associated with a radial scar. Eight radial scars were detected incidentally as a result of screening mammography; three of these cases manifested as stellate lesions. All lesions were unilateral. Microscopically, all radial scars had a stellate configuration, with a central fibroelastic core from which numerous ductules radiated. In eight cases, lobular neoplasia (LN) involved the peripheral ductules in a patchy fashion; seven of these cases were graded as LN 2 and one as LN 1. A grade II intraductal carcinoma with solid and cribriform patterns was noted in three cases, one of which was noteworthy because the central core contained DCIS (grade II) distorted by the dense fibroelastic tissue, mimicking an invasive pattern. An immunostain for actin demonstrated the presence of myoepithelial cells surrounding all the entrapped ductules confirming their noninvasive nature. An invasive carcinoma was present in the remaining six cases; these were predominantly focal and in the peripheral region of the radial scar. While all invasive carcinomas were well differentiated and ductal in type with abundant tubule formation, only one was a classic tubular carcinoma. In all six cases it was difficult to detect the malignant infiltrating nature of the lesion because of the associated stromal fibrosis and distortion of surrounding tubular structures. The occurence of neoplastic and malignant lesions involving or arising in a radial scar has received scant attention in the literature. This series indicates that the ducts and lobules emanating from radial scars can serve, albeit rarely, as the milieu for the development of or secondary involvement by lobular neoplasia, intraductal, or invasive carcinoma. It should be emphasized that these cases reflect a highly select group of problematic radial scars in a high-volume consultation practice; the vast majority of radial scars encountered in routine practice of surgical pathology are benign. At present there is no evidence that the scar element of the lesion serves as a precursor or promoter of the various neoplastic changes.