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Shah et al. Breast metastasis mimicking as second primary cancer

Figure 6: Immunohistochemistry markers results in our patient. CK: cytokeratin; mCEA: carcinoembryonic antigen; ER: estrogen receptor;
MUC2: mucin2; CDX2: Caudal type homeobox2
breast they lack an in situ component. Lymphovascular indicates a poor prognosis. Metastases to the breast
space invasion may be prominent. This type of unusual are rare in themselves, and such metastasis occurring
histopathology in breast with previous history of secondary to a previous anorectal carcinoma makes
malignancy are suggestive of metastasis. But the final this case very unusual. The liver, lungs and bone are the
diagnosis is established after studying the cytokeratin usual sites of spread from colorectal cancers. Breast
pattern. IHC when performed, tends to be positive for metastases with sparing of these organs is unlikely but
colorectal markers like caudal type homeobox-2 (CDX- possible. Our patient presented with an isolated breast
2), cytokeratin (CK20), and CEA, and negative for lump and without any other complaints. She was
breast markers CK7, estrogen receptor, progesterone managed considering the lesion to be second primary
receptor, human epidermal growth factor receptor-2, cancer of the breast but post operative histopathology
and gross cystic disease fluid protein-15. [14,15] with IHC showed it to be metastases. On the basis of
Expression of CK7 and CK20 is considered to be most histopathology showing adenocarcinoma and history
helpful in identifying the origin of adenocarcinomas. of previous malignancy alone, the diagnosis of lesion
being metastasis to breast should not be arrived upon
Most importantly, the great majority of primary breast and in such patients the importance of IHC to exclude
tumors are CK7-positive and CK20-negative, while the diagnosis of primary breast lesion cannot be
colorectal carcinomas are usually CK7-negative and undermined.
CK20-positive. [16,17] IHC markers used in our case were
consistent with these findings as shown in Table 1. The Financial support and sponsorship
strong nuclear positivity with CDX-2 is highly sensitive Nil.
and specific for colonic cancers. In addition, estrogen
[18]
and progesterone receptors are usually negative in Conflicts of interest
metastatic breast cancers. A patchy reaction for CK5/6 There are no conflicts of interest.
and comedo like necrosis can mimic ductal carcinoma
in situ disease. Histological features such as epithelial Patient consent
stratification, high nuclear atypia, significant mitotic Obtained.
activity, and positive reactions for CK20 and CDX-2 can
help to overcome this difficulty. Metastatic carcinomas Ethics approval
in the breast are associated with a poor prognosis with Ethics approval was obtained prior to the
a survival rate of less than 12 months from the time of commencement of the study.
breast tumor diagnosis. [16,19,20]
REFERENCES
Metastatic disease in the breast is a marker for
disseminated metastatic spread, and therefore 1. Hajdu SI, Urban JA. Cancers metastatic to the breast. Cancer
394 Journal of Cancer Metastasis and Treatment ¦ Volume 2 ¦ September 30, 2016