The goal of breast reconstruction is to restore the breast as normally and attractively as possible while minimizing visible scars. In the discussion of reconstruction after breast cancer, the breast has been arbitrarily divided into quadrants. Although quadrants are easy to comprehend and communicate, they neither represent the teardrop shape of the breast nor consider lines of demarcation.

Reconstructive lip or nose surgeons use a reconstructive subunit principle. For example, Millard used the Abbe flap to replace the entire filtrum in unsuccessful cleft lip repair (1). Burget and Menick’s nasal subunit description expanded on his theory by advocating the replacement of complete unit nasal reconstruction to place the borders in shallow valleys and on the lighter ridges of the nasal surface (2).

A similar philosophy in breast reconstruction is appealing to assist the surgeon in choosing a more cosmetically attractive option. The breast differs from the nose in that it lacks shadows and ridges, yet there are skin-type transitions at the areola and inframammary fold (IMF). Unlike the situation with regard to the nose, clothing usually covers the majority of the breast. Therefore, clothing and tan lines compose other transitions of the breast that assist in breast reconstruction camouflage. The superomedial aspect next to the sternum is most often exposed. Uncovered incision lines that extend onto the superomedial aspect of the breast are unsightly. The visible short transverse incision for placement of the chemotherapy infusion catheter is frequently unattractive and placed without consideration for aesthetics. It is prominent, fails to hide in any light shadows or creases, and is virtually impossible to camouflage. In contrast to this obvious scar is an incision placed at the IMF, which provides an excellent transition between reconstruction and native skin. This is the beginning of a subunit principle of the breast. Execution of the principle may require a sacrifice of the residual native skin superior to the IMF, but the long-term results will be improved. Restifo advocated this principle in delayed transverse rectus abdominis myocutaneous (TRAM) reconstruction (3).

This concept has been expanded upon in the recent literature with the popularity of free tissue autogenous reconstruction (4). Pulzl et al. in their paper appropriately titled “Respecting the Aesthetic Unit in Autologous Breast Reconstruction Improves the Outcome” discussed a plan change when using microvascular tissue. Because one of the risks of free flaps is total failure, a lifeboat is incorporated. The area between the mastectomy scar and the inframammary fold is deepithelialized and buried under the free flap. This ultimately serves three functions: (a) It avoids a “double-bubble” by hiding the transition of the free flap and the mastectomy flap at the IMF, (b) it provides greater bulk at the lower half of the breast, and (c) it maintains tissue coverage of the chest in the event of free flap loss (5,6).

Two subsequent papers emphasized a change in thinking in breast reconstruction. As stated by Blondeel et al. (7), “sculpting a flap of autologous tissue into an aesthetically pleasing breast has become the most demanding, while the technical aspects of flap harvesting and microsurgery have become routine in most centers.” This sentiment was echoed by Davison, who felt that maximizing aesthetic outcomes for the reconstructed breast was a priority (5). Similarly, Blondeel et al. also advocated a deepithelialization of the skin below the scar to the IMF to maximize aesthetic results.

Coutinho et al.’s prospective study made an excellent attempt to identify aesthetic implications of scar or flap position in breast reconstruction (8). To simulate scars, lines were drawn on normal breast pictures with intact areolar complexes to neutralize distracting variables. Patients were surveyed on preferable scar/flap patterns. In these results, a single line scar was preferred over a flap unless the scar extended into the superomedial quadrant of the breast. Flap reconstructions that transitioned at the IMF and spared the upper medial quadrant were rated higher than other flaps. Incisions that ran vertically in the lower midline of the breast and that would be covered by a bra cup were rated as acceptable.

A consistent problem with reconstructions is the patchlike appearance of poorly placed skin and scars. Frequently, flaps are eccentrically placed where the incision was made (often one that incorporates previous biopsy sites), without thought to the final prospective. Restifo (3), Hidalgo (9), Gabka et al. (10), and Nahai (11) condemned this type of appearance. Development of the circumareolar mastopexy, with immediate reconstruction using either the TRAM or latissimus flap as described by Bensimon and Bergmeyer (12), has raised the standard for autogenous reconstruction. After devising a subunit principle for the breast, we now use it in preoperative and intraoperative planning for such reconstructions. Application of the subunit principle has favorably influenced results, particularly in changing eccentric skin-sparing mastectomy incisions to circular periareolar defects and replacing the entire breast as a subunit with free TRAM reconstructions.

Taking this decision to its extreme is the decision on the placement of incisions for nipple-preserving, skin-sparring mastectomies (13). This raises the question whether the incision is better placed around the areola or in the IMF. The extrapolation of this aesthetic subunit principle to incision placement will continue to be debated as interest in both oncoplastic surgery and the treatment of genetically at-risk patients increases.