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Tattoo Ink Within Lymph Nodes: A Possible Clinical Mimicker of Abnormal Calcifications

A 35-year-old female presented clinically with a tender left breast mass. Mammogram and ultrasound was significant for a 2.1 cm high density, antiparallel mass with ill-defined margins, located in the middle third of the breast at 12 o’clock. BI-RADS score was 5, highly suggestive of malignancy. Stereotactic core biopsy of the mass revealed invasive ductal adenocarcinoma, grade III, with basaloid features. Ancillary studies revealed the tumor to be negative for ER and PR immunohistochemical stains, and Her2 ISH. The patient underwent neo-adjuvent chemotherapy with good response, and following completion of therapy a preoperative mammogram was obtained. At this time, the original mass was noted to have decreased in size to 1.2 cm, but an additional group of amorphous, clustered calcifications were seen in the posterior third of the left breast at 4 o’clock (Fig. 1). BI-RADS score was 4, suspicious for malignancy; the differential diagnosis included DCIS, treatment effects, or dystrophic benign calcifications. A stereotactic biopsy of this region was performed. A postbiopsy specimen radiograph confirmed the presence of calcifications within the excised breast parenchyma (Fig. 2A). Microscopic examination of the biopsy revealed fragments of an intraparenchymal lymph node, with prominent black particulate pigment material that was suggestive of tattoo ink (Fig. 2B). There was no evidence of invasive carcinoma, DCIS, or the calcium pyrophosphate that is typically seen in breast calcifications, in any of the core biopsies. Polarization microscopy did not show evidence of calcium oxalate or other polarizable material that could have explained the radiographic calcifications. The formalin-fixed paraffinembedded tissue block was reimaged, confirming the presence of calcifications within the tissue. Additional levels performed on the block again showed prominent tattoo ink within a lymph node without evidence of associated malignancy, and the presence of this tattoo ink seemed to correlate with the calcifications seen within the specimen radiograph. Thus, it was felt that the tattoo pigment was responsible for the calcificationlike findings seen on initial mammography. The final diagnosis was intramammary lymph node, with prominent tattoo pigment. Clinical follow-up confirmed the presence of multiple tattoos on the upper arm of the patient, and no evidence of disease progression at this site was seen on most recent mammogram. Since the current case was an example of tattoo ink resulting in a clinical false-positive imaging result, we