Concurrent fibroadenoma and intraductal papilloma - A recurring complex lesion in a premenarcheal girl.

Breast diseases are rare in childhood and adolescence, most lesions being fibroadenomas and papillomas. We report the case of an 11-year old girl with a complex breast lesion with hybrid features of fibroadenoma and intraductal papilloma with an early recurrence. Microscopically, the lesion was composed of dilated ducts showing intraluminal papillary projections with small to broad fibrovascular stalks. The typical leaf-like appearance of fibroadenoma was determined by the presence at the periphery of ducts compressed and distorted by the prominent stromal component. Despite its florid epithelial hyperplasia and mild cytological atypia (more evident in the relapse), immunohistochemical staining for p63 and smooth muscle actin highlighted a continuum outer myoepithelial layer, confirming the non-invasive appearance of the lesion. Two pathogenetic links have been hypothesized: one is based on the morphological continuum between these two entities, which may represent different evolutive stages in the same lesion; the other is based on epithelial/mesenchymal interactions. The possible malignant transformation of such complex lesion is also discussed, along with its differential diagnoses. The relevance of this case lies in its rarity, as well as in the therapeutic strategies related to its biological potential and to the necessity of a conservative treatment, due to the young age of the patient