Type:
Educational Exhibit
Authors:
P. L. Moyle, S. Hunter, S. O'Keeffe, R. Gaskarth; Cambridge/UK
DOI:
10.1594/ecr2010/C-0362
Background
- The role of DWI is well established in characterisation of benign from malignant breast tumors on the basis of ADC values.
- The use of DWI allows information regarding tissue function as well as structure to be obtained [1].
- Malignant tumors are characterized by high cellularity, causing restricted diffusion of water molecules and causing lower ADC values than benign lesions regardless of the b-value or the technical differences [2-5].
- Mucinous carcinomas of the breast are rare (1–4% primary breast cancers), more likely to occur in older patients and overall have a better prognosis than infiltrating ductal carcinomas [6].
- Histologically the tumor present as clusters of uniform round cells within large pools of extracellualr mucin ( figure 1).
- The volumes of mucin enables water molecules to move freely resulting in ADC values considerably higher than that of other breast malignancies, sometimes higher than benign breast lesions and may even overlap that of normal breast tissue.
- Therefore it has been suggested that mucinous carcinoma can be clearly differentiated from other breast tumors on the basis of ADC values [4].
- Other MRI characteristics of mucinous tumours include:
- Moderate uptake of contrast (slow rising type I or plateau type II curve)
- Very high signal on T2W and rim or heterogeneous pattern of enhancement.
- T1-W imaging can vary from low to high signal intensity (Mucin is believed to affect SI on T1-weighted images because of its protein content) [6, 7].
We present the MRI features of three cases of mucinous breast tumours, particularly illustrating how the cellular morphology of this tumour gives unexpectedly high ADC values for a malignant lesion.