During the period from January 2009 to October 2014,
we searched the terms mucin,
mucocele and mucinous in our radiology department database.
The research resulted in 41 lesions in 40 patients with histological diagnosis of diseases with extracellular mucin from a total of 5227 patients submitted to imaging-guided breast biopsy during the same period.
The age of the patients ranged from 36 to 84 years old,
mean age of 57 yo.
We retrospectively analyzed the mammograms,
ultrasounds and MRI of those patients according to the BI-RADS® lexicon and compared the findings with the pathological results.
Of the 41 lesions,
9 were pure mucocele-like tumors,
5 were associated with atypia,
2 with ductal carcinoma in situ,
and 25 were associated with invasive carcinoma (Table 1).
The mammographic findings in pure mucocele-like tumors were amorphous calcifications in 3 cases (34%),
coarse heterogeneous calcifications in 2 cases (22 %)(Figures 1,2,3 and 4) and pleomorphic calcifications in 1 case (11%).
For the 3 remaining cases of pure MLT only ultrasound images were available,
one corresponding to a circumscribed mass and 2 cases to not circumscribed masses (Table 2).
Follow up exams were available for only 2 pure MLT,
one submitted to surgical excision with pathological diagnosis compatible with mucocele-like tumor without atypia.
The other case was followed for 12 months showing stability of the circumscribed mass.
Intraductal proliferative lesions like flat epithelial atypia (Figures 5 to 9) and atypical ductal hyperplasia were classified in the category of mucocele-like tumor associated with atypia.
In a total of 5 lesions with atypia,
4 were reported as amorphous calcifications on mammography and one case showed calcifications with segmental distribution; only 1 case of punctate calcifications was reported (Table 3).
Two patients underwent breast-conserving surgery,
one showing similar result of MLT with flat epithelial atypia and the other presented a result of DCIS in the surgical specimen.
The two cases of MLT with CDIS were reported as amorphous calcifications on mammography.
These two patients underwent breast-conserving surgery with DCIS with mucin in the surgical specimen.
Mucinous carcinoma is characterized by cell mucin production of varying amounts,
which are detected in the tumor stroma.
The pure MC of the breast is characterized by mucin in more than 90% of the tumor volume and the mixed type has less than 90% of well differentiated mucinous subtype associated with the presence of less differentiated cells of another type of invasive ductal carcinoma.
Invasive mucinous carcinoma was characterized on mammography as not circumscribed masses in 54% of the mammographic exams.
Three cases (27%) have been reported as pleomorphic calcifications on mammography,
two with segmental distribution.
On ultrasound,
invasive carcinoma was reported as irregular masses with not circumscribed margins in 87% of the cases.
On MR,
two cases presented as non-mass enhancement (Figure 3) and two cases presented as circumscribed masses.
The rest of the cases were reported as masses with irregular morphology and margins (63%) and in 100% of the invasive carcinomas with mucin,
high signal intensity on T2 was observed (Table 4) (Figures 10 to 29).
The diseases with extracellular mucin had many mammographic,
ultrasound and MRI appearances but most frequent they presented as amorphous calcifications or irregular masses with high-signal intensity on T2 weighed images.