Imaging diagnosis
Case 217
【Progress】
She was introduced to the hospital expert for breast cancer. She was scheduled to receive tumor resection. We were waiting for the histologic results of the specimen. Lately, it revealed a breast cancer.
【Discussion】
It is imperative to differentiate breast cancer from benign tumor on MRI. It is well known that Gd-dynamic enhanced MRI is evaluated a golden standard to differentiate it by comparing the Gd-washout pattern (1). The marked decrease in delayed phase of Gd-enhanced signals of tumor obtained in arterial phase implies breast cancer and the increase or the maintenance of Gd-enhanced signal in delayed phase of them implies benign tumor. Although Gd enhancement is not available, MRI with weighted image and ADC values is also useful for the differentiation. It is reported that ADC values become lowering in breast cancer and become elevating in benign tumor (2, 3). The cutoff values to breast cancer differentiating from benign tumors are less than 1.0 (3).
However, the phyllodes tumor which belong to benign tumor is exceptional. The accumulation reviews of ADC values on phyllodes tumor are yet to be known. The case report says ADC values of phyllodes tumor were below 1.0. In our case, the ADC values of breast tumor was 0.75.
There are three main benign tumors in breast: fibroadenoma, phyllodes tumor and hamartoma. Fibroadenoma and phyllodes tumor are similar in pathology. They compose of fibrous tissue and epithelial tissue (4-6). Phyllodes tumor own growing factor (gene) of epithelial component and it sometimes grows rapidly. It can grow more than 10 cm. The average age is around 45, indicating to the close age of menopause. The phyllodes tumor occurs in less than 1% (6, 7). Meanwhile, fibroadenoma is deficient of growing factor and it sometimes decreases in size spontaneously. It rarely grows more than 3 cm. The average age is around 25. Fibroadenoma is the most common of the benign breast tumors. Popcorn calc on mammography is prominent where it arises from epithelial tissue.
Hamartoma composes of not only fibrous and epithelial tissue but also lipid, gland and smooth muscle tissue. The key is the presence of lipid to differentiate hamartoma from fibroadenoma and phyllodes tumor on imaging diagnosis. Hamartoma occurs in 0.1 to 0.2 % of all breast tumors and in less than 5% of benign breast tumors (4, 5).
Of the three benign tumors, ADC values of fibroadenoma and hamartoma are high, whereas those of phyllodes tumor might be low. ADC values depend on water molecular diffusion and microcirculation. Water diffusion is restricted by cellular dense, high protein fluid and mucin fluid. The phyllodes tumor proliferation is considered to increases cellular dense inducing low values of ADC. The more accumulation data on ADC values of phyllodes tumor should be warranted for the evaluation.
【Summary】
We presented a seventy eight-year-old female with a hard mass sized 3cm X 3cm in her right breast. Mammography, non-enhanced CT, and MRI with fat suppression T2WI and T1WI did not depict the presence of the tumor but contrast-enhanced CT and MRI with diffusion WI and ADC values depict the tumor. ADC values of the tumor was approximately 0.75. This tumor was not contradictory to phyllodes tumor but histologic examination revealed breast cancer. It is borne in mind that cutoff values of ADC to differentiate breast cancer from benign tumors are less than 1.0. There are three benign tumors in breast: fibroadenoma, phyllodes tumor and hamartoma. Both fibroadenoma and phyllodes tumor own fibrous component and epithelial component microscopically and the difference is that phyllodes tumor have the epithelial component with growth factor (gene), inducing rapidly growing, while fibroadenoma is deficit of growth factor, inducing decrease in size as time pass. Hamartoma contains not only fibrous and epithelial components but also lipid and gland components. Then, the key to differentiate hamartoma from fibroadenoma and phyllodes tumor on imaging diagnosis is whether the tumor contain lipid component or not.
【References】
1.Feder JM, et-al. Unusual breast lesions: radiologic-pathologic correlation. Radiographics. 1999;19 Spec No : S11-26.
2.Amornsiripanitch N, et al. Diffusion-weighted MRI for Unenhanced Breast Cancer Screening. Radiology. 2019 Dec;293(3):504-520.
3.Pereira1 FPA, et al. Assessment of Breast Lesions With Diffusion-Weighted MRI: Comparing the Use of Different b Values. AJR 2009; 193:1030–1035.
4.Arrigoni MG, et al. The identification and treatment of mammary hamartoma. Surg Gynecol Obstet. 1971;133 (4): 577-82.
5.Murat A, et al. Hamartoma of the breast. Australas Radiol. 2007;51 Spec No. : B37-9. doi:10.1111/j.1440-1673.2007.01818.x - Pubmed citation
6.Tan BY, et al. Phyllodes tumours of the breast: a consensus review. Histopathology. 2016;68(1):5‒21.
7.Ng CCY, et al. MED12 is frequently mutated in breast phyllodes tumours: a study of 112 cases. J Clin Pathol. 2015;68:685–91.
2021.1.6