Simulation of microcalcifications on specimen radiographs of breast biopsies by inks used in marking the surgical resection margins.

In routine practice, the evaluation of breast excisional biopsy specimens is assisted by the use of various tissue marking inks to delineate surgical margins and preserve tissue orientation. These inks may simulate microcalcifications in specimen and tissue block radiographs. The magnitude of this problem is studied by systematically identifying the factors leading to the creation of this artifact. Samples of fresh tissue from breast reduction mammaplasties were painted separately with fresh wet ink and ink mixed with dried powdery residue. Black India ink and commercial colored tissue inks (the Davidson Marking System) were tested. The painted tissues were radiographed before and after routine paraffin embedding. Routine histologic sections were obtained from each tissue block for microscopic examination. Compared with unmarked controls, samples inked with blue, green, and red inks containing powdery residues showed radiopaque artifacts on radiographs prior to tissue processing. Only the sample marked with red ink showed residual radiopaque artifacts after processing. Microscopically the dried red ink particles were readily distinguishable from microcalcifications on the tissue sections. On the tissue radiographs, the dried ink artifacts were indistinguishable from true microcalcifications. This study demonstrates that some tissue marking inks used in the pathology laboratory are radiopaque. Inks contaminated with particles of dried residue, often present on ink container lids, may appear as artifacts mimicking microcalcifications on specimen and tissue block radiographs, occasionally complicating the histologic localization of mammographically demonstrated microcalcifications. Tissue marking inks should be tested for radiopacity prior to use on breast biopsies. Ink containers should be checked frequently for buildup of dried residue.