Histopathological comparisons of irradiated and non-irradiated breast skin from the same individuals.

Because of increasing indications for post-mastectomy irradiation and a growing demand for breast reconstruction using expanders and implants, both these procedures are performed in increasing numbers of patients. Although it is known that irradiation increases the difficulty of subsequent breast reconstruction, there is still insufficient information regarding differences in radiation-induced histopathological changes between individuals. In this study, we had the opportunity to take skin biopsy specimens from both the irradiated and non-irradiated breasts of 20 patients, and examine the histopathological differences between them. Skin was taken from the irradiated breast of 20 patients at the time of breast reconstruction, and skin was taken from the contralateral non-irradiated breast at the time of contralateral reconstruction, reduction or implant insertion for augmentation. A horizontally oriented specimen of skin was taken from both sides. Specimens were horizontally sliced and histopathologically examined by light microscopy and scanning electron microscopy (SEM). We identified five characteristic histological changes in the irradiated breast skin: (1) hyperplasia of the epidermis; (2) flattening of the papillary layer; (3) atrophy of dermal appendages; (4) high density of dermal collagen fibres; and (5) unidirectional alignment of the dermal collagen fibres (UACF). UACF was further confirmed by SEM. UACF seemed to be strongly associated with complications. These histopathological findings correlated with the difficulty of expanding irradiated skin, resulting in poor aesthetic outcomes such as capsular contracture and expander/implant extrusion. Careful attention should be paid to the techniques of breast reconstruction after irradiation.