Abstract
Here we report the case of a 77-year-old woman with a huge cancer of the right breast for which size was measured on computed tomography in our hospital preoperatively and in other hospital 3 years earlier. During the 3-year untreated interval, the tumor grew from 4 cm to 13 cm in maximum diameter, and the tumor-volume doubling time (TVDT) was calculated as 209 days. The patient underwent mastectomy with axillary lymph node dissection, with the large skin defect covered by autologous skin graft. The pathological diagnosis was pure mucinous carcinoma (MC) of the breast with a low MIB-1 index, no vessel invasion, and no lymph node metastasis. Breast MC has been known to show a slow growth rate, but the TVDT of this current tumor was not markedly different from that of common breast cancers described in previous reports. This short TVDT notwithstanding the low aggressiveness may be due to abundant mucin occupying the majority of the tumor volume. To the best of our knowledge, no previous reports have provided accurate TVDTs for breast MC.
Introduction
Mucinous carcinoma (MC) of the breast is a special type of breast carcinoma, accounting for 1–6% of all invasive mammary cancers [1]. MC of the breast is divided into pure and mixed types [1]. In pure MC, the mucinous component represents over 90% of the tumor, whereas mixed MC is 50–90% mucinous component, usually with an infiltrating ductal epithelial component [2]. Pure MC shows a far better prognosis than either common-type invasive breast cancer or mixed MC (10-year survival rates: 90.4% vs. 63.5% or 66.0%, respectively) [3]. Although pure MC is considered to be slow growing, no reports have provided exact measurements from imaging modalities during untreated periods. A case of huge pure MC in which surgery was performed 3 years after diagnosis is described here, with measurements from computed tomography (CT).
Case report
A 77-year-old postmenopausal woman visited our hospital in May 2014 with a huge mass in the right breast, oozing bloody exudate from the nipple (Fig. 1). The mass was elastic hard and occupied almost the entire right breast. The mass had been pathologically diagnosed as MC of the breast based on core needle biopsy (CNB) specimens from the same lesion at another hospital in May 2011. At that time, the mass had measured 4 cm in maximum diameter on CT (Fig. 2). The patient had been recommended to undergo mastectomy by a doctor at the previous hospital, but had declined to undergo surgery out of fear regarding the operation. The mass had gone untreated for 3 years and had grown to 13 cm in maximum diameter on CT (Fig. 2) and magnetic resonance imaging (MRI) (Fig. 3). CNB at our hospital in May 2014 confirmed MC of the breast. In June 2014, the patient underwent mastectomy and axillary lymph node (LN) dissection. A split-thickness skin graft obtained from the left thigh was transplanted to 14
Discussion
MC of the breast is usually seen in postmenopausal elderly women. The incidence of LN metastasis from pure MC of the breast has been reported as very low, but the omission of axillary LN dissection has remained controversial in cases involving huge tumors [4–6]. The current case underwent axillary LN dissection, but showed no metastases at this LN station. The average size of breast MC has been reported as 1.8–2.8 cm [7,8]. The present case represented a huge tumor compared to previous reports of breast MC [4,9]. The tumor-volume doubling time (TVDT) for the current tumor was calculated as 209 days, using the maximum diameters measured on CT between June 20, 2011 (t1) and May 14, 2014 (t2) and the following formula, based on an assumption of constant exponential tumor growth [10,11]: