Imaging Appearances of Pseudoangiomatous Hyperplasia of Mammary Stroma: Case Reports

Abstract

A 34-year-old pre-menopausal women complained of ‘tingling’ in the outer half of the right breast which was associated with enlargement of the breast. There were no other symptoms. On examination the right breast was noted to be larger than the left breast. A discrete mass was not palpated. Mammography showed a uniform increase in the density of the breast but a discrete mass was difficult to identify (Fig. 1). Subsequent ultrasound demonstrated a large predominantly echogenic lesion with a well-defined wall and occasional cyst-like areas at its periphery. It was so large that it was not possible to measure the size of the lesion accurately, although using the cursors on the ultrasound image enabled an antero-posterior size estimate to be made (Fig. 2). Fine needle aspiration cytology (FNAC) was inadequate. Trucut biopsy showed scanty fragments of fibrocollagenous tissue with a few ductal clusters but a definitive diagnosis remained elusive. Magnetic resonance imaging (MRI) of the breast was undertaken on a Siemens Open 0.2T system using a shoulder coil with the patient in a semisupine position. T1-weighted spin-echo images (TR 420, TE 15 ms) were obtained before and after intravenous administration of 20 ml (9.4 g) dimeglumine gadopentetate (Gd-DTPA, Magnevist, Schering Health Care). Repeated T1W sequences were undertaken immediately following administration of the contrast agent but a dynamic sequence was not employed in this instance. These images confirmed the presence of a well-encapsulated lesion measuring 10 cm in diameter with signal characteristics strikingly lower than the adjacent fat. The lesion had a mixed signal pattern with areas of intermediate signal interspersed with islands of low intensity. The cystic lesions shown on ultrasound were difficult to identify on the non-enhanced images but were clearly identified after GdDTPA by the presence of an enhancing margin (Fig. 3). T2-weighted turbo spin-echo images (TR 3879, TE 102 ms) showed a low signal capsule encasing a lesion which was predominantly of high signal but within which there were areas of low signal (Fig. 4). The fluid nature of the cystic lesions noted on ultrasound was confirmed with low signal on T1W and high signal on T2W. An encapsulated mass measuring 13 × 11 × 3 cm was excised from the breast. The cut surface was mainly solid but with a few cysts at the periphery (Fig. 5). On microscopy the mass had a normal mixture of stromal and epithelial elements but the epithelium showed extensive microcystic change and occasional macroscopic cysts separated by abundant stoma containing a network of spaces lined by myofibroblasts (Fig. 6); this was confirmed by using S100 and factor VIII staining. A diagnosis of pseudoangiomatous hyperplasia was made.