Purpose: A mucinous breast carcinoma has a better prognosis than an invasive ductal carcinoma, so it is important to differentiate between pure and mixed mucinous carcinomas of the breast because the former has a more favorable prognosis. We
investigated the clinical features of mucinous carcinomas of the breast and the differenting characteristics of the two types. Methods: A retrospective review was done of 31 patients with a mucinous breast carcinoma who had been treated between
Sep.
1994 and Aug. 1999 at the Department of General Surgery, Samsung Medical Center. The clinical features and the radiologic and pathologic findings were assessed. The pure type was defined as a carcinoma with a mucin component of 50% or more.
Results: The
clinical characteristics, including age distributions, symptoms & signs, and tumor locations, were similar to those of other types of breast cancer. Mammography in cases of malignancy showed an ill-defined mass density with pleomorphic or
granular
calcifications in 8/19 cases (42.1%), an ill-defined mass density without calcifications in 2/19 cases (10.5%), and pleomorphic calcifications only in 1/19 (5.3%) cases. Other findings were indicated as benign: a well-circumscribed mass in 4/19
(21%),
smudged or ring-like calcificaitons in 3/19 cases (15.8%), and a negative finding in 1/19 cases (5.3%). Ultrasonography showed well- or ill-defined masses in 14 cases and 7 of those 14 cases (50%) were diagnosed as being malignant. The cytologic
findings for 21 cases showed tumor cell clusters with mucous backgrounds. Among those 21 cases, 19 (90.5%) were diagnosed as being malignant. Breast conservation surgery was performed on 10 patients (32.3%) and a modified radical mastectomy on 21
patients (67.7%). Among 31 cases, 21 cases were a pure type, and the rest were a mixed type with an invasive component. Tumor cell nests floated in a profuse extracellular mucin pool. The pure type showed a smaller tumor size (p=0.001) and less
nodal
metastasis (p=0.047). Early stages (stage IIa or less) were more common in pure type (76.2%) than in the mixed type (40%)(p=0.025), but there were no differences in hormonal status between the two types. Conclusion: There were no differences in
the
clinical characteristics between mucinous and other types of breast carcinomas, but the radiologic findings for mucinous carcinomas were not typical of a malignancy. Cytologic examinations were useful in diagnosing mucinous carcinomas of the
breast.
Since the tumor sizes were smaller and axillary nodal metastases were rare in pure mucinous carcinomas, it is important to differentiate it from the mixed type.
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