Giant tubular adenoma of the accessory breast in the anterior chest wall occurred in a pregnant woman

Background Tubular adenoma of the breast is a rare benign epithelial tumor and only a few literatures have been reported; so far, no cases of tubular adenoma occurred in the accessory breast have been reported in the English literature. Clinical presentation and management of our patient are discussed along with a review of the literature on accessory mammary and tubular adenoma. Case presentation We present a case of 26-year-old woman (gravid 4, para 1) at 37 weeks of pregnancy with rapid enlargement in left anterior chest wall during pregnancy. Physical examination showed the left accessory breast was obviously bigger than the right one that only had a light areola around a small nipple. An elastic, mobile well-circumscribed mass measuring approximately 15 cm × 15 cm was palpated. Moreover, it was edematous and congestive with an increase in local temperature. The breast ultrasound further demonstrated the mass was a relatively homogeneous solid with short stripe blood flow signal. A single live fetus of 37 weeks gestation was observed by abdominal ultrasound scan. After a 2850 g male neonate was delivered, the right accessory breast and the mass in left accessory breast were removed. The resected specimen appeared as a solid white elastic mass with a smooth surface and the cut surface was red-grayish. Microscopically, the lesion consisted of tightly packed homogenous glandular structures which are supported by a single layer of myoepithelial cells with sparse intervening stroma. Conclusions We describe a very rare case of giant tubular adenoma arising within an accessory breast in the anterior chest wall in a late pregnancy woman. The high concentrations of estrogen, progesterone and prolactin might account for the significant tumor enlargement during pregnancy. To our knowledge, this is the first case of giant tubular adenoma occurred within the accessory breast in the anterior chest wall. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6210811191552106 .