Teaching Case

A 43-year-old female presented with a palpable lump within the right breast for 1 month.

On ultrasound, the palpable lump corresponded to a lobulated complex cystic mass, measuring 5.1 x 1.1 cm (Figure 1a). It demonstrated multiple cystic spaces and a solid component with intrinsic vascularity (Figure 1b).

Mammographic projections (Figures 2a, 2b and 2c) revealed a heterogeneous mass with internal dependent calcifications. On the mediolateral oblique and mediolateral views (Figures 2b and 2c), the calcifications appeared as semilunar, crescent-shaped or teacups, typical of milk of calcium.

On the recombined images of the contrast-enhanced mammogram (Figures 3a, 3b and 3c), the mass showed heterogeneous enhancement with multiple tiny non-enhancing components corresponding to the sonographic internal cystic spaces. There was a washout on the delayed mediolateral view (Figure 3c), a finding that should raise concern for malignancy.

Ultrasound-guided biopsy (Figure 1c) and surgical pathology revealed high-grade ductal carcinoma in situ with cribriform architecture associated with comedonecrosis and teacup calcifications (Figures 4a, 4b and 4c). Note Figures 5a, 5b and 5c, where the radio-pathological correlation of the layering calcifications is put in perspective.

Milk of calcium calcifications are found in 4–6% of diagnostic mammograms [1]. As a general rule, they are considered typically benign by the BI-RADS lexicon [2] and usually represent sedimented calcifications within benign cystic lesions or fibrocystic changes [3,4]. Its appearance of dense, linear and curvilinear “teacup” layering is considered pathognomonic in the mediolateral (ML) and mediolateral oblique (MLO) views. On the craniocaudal (CC) projection, they should have a “cloudlike” or smudgy appearance, like tea leaves in the bottom of a teacup, whereas ductal carcinoma in situ (DCIS) retains a linear shape [3].

Although uncommon, milk of calcium calcifications can be associated to malignancy. In the review by Linden and Sickles [1], 4% of cancers were associated with milk of calcium calcifications. However, malignancies related to milk of calcium were described near or adjacent, not within them [1,5].

The interesting fact about this case is that the teacup calcifications were located not in the periphery, but within the cystic spaces generated by a high-grade DCIS with comedonecrosis (Figures 4a, 4b and 4c). The surgical piece was reviewed, and there were no fibrocystic changes associated that could contribute to the appearance of milk of calcium. Incidentally, there was a small focus of invasive carcinoma in situ (not shown).

The teaching point is that not all milk of calcium calcifications are benign. It is necessary to evaluate ancillary findings associated to the calcifications. In this case, the presence of milk of calcium within a complex cystic mass should always prompt a biopsy in order to rule out malignancy. Although debatable, one could say that there were also linear and pleomorphic calcifications within the mass, which is very challenging to assess given the extensive component of milk of calcium.

All patient data have been completely anonymised throughout the entire manuscript and related files.