A 40-year-old woman presents for evaluation of a palpable mass at the 3 o’clock position of the left breast (figures 1-4). What is your diagnosis?
A 40-year-old woman pre-sents for evaluation of a palpable mass
at the 3 o'clock position of the left breast (figures 1-4). What is
Medullary carcinoma is a subtype of infiltrating ductal
carcinoma, accounting for 5% to 7% of all breast cancer. It is
characterized by its well-circumscribed borders, sheets of poorly
differentiated cells with high nuclear grade, and prominent
lymphoid infiltration both in and around the tumor. Up to 60% of
patients with medullary carcincoma are under 50 years old and it
represents 11% of breast cancers in women 35 years of age or
The prognosis is more favorable than with other ductal carcinomas,
with reports of 10-year survival rates as high as 92%.
Mammographically, medullary carcinoma typically appears as a
well-circumscribed, medium to high density, non-calcified mass with
lobulated contours. Occassionally, there is a partial or complete
"halo sign" of surrounding lucency.
Reactive axillary adenopathy even without nodal metastasis is a
On gross pathology, there is typically a distinct margin between
the tumor and the surrounding breast tissue and, if there is
significant peripheral fibrosis, the appearance is that of an
encapsulated lesion. The borders "push" rather than infiltrate the
surrounding tissue. On microscopic pathology, sheets of solid
syncytium like large cells with pleomorphic nuclei and mitosis are
surrounded by a lymphoplasmacytic reaction which results in the
smooth, rounded contour seen on mammography.
There is a lack of tubule formation. The diagnostic work up of such
a palpable mass should include ultrasound examination to exclude a
cyst. If a solid mass is noted, ultrasound-guided core needle
biopsy is appropriate to allow definitive management. Based on
mammographic features, other diagnostic considerations include both
benign and malignant lesions. The presence of adjacent and
coalescing nodules favors malignant etiology in this case.
Intracystic papillary carcinoma and mucinous (colloid) carcinoma
also often present as relatively well-defined, dense masses. Among
benign lesions, a fibroadenoma or phyllodes tumor would be the most
likely considerations. Although this process was mammographically
dense, complex cysts or papillomas could also have this
Prepared by Barbara M. Jaeger, MD, and Wendie A. Berg, MD,
PhD, Department of Radiology, University of Maryland School of
Medicine, Baltimore, MD.