Mammographic artifact leading to false-positive result.

Dear Editor,

A female, 75-year-old was referred by another service with previous screening mammogram demonstrating clustered pleomorphic microcalcifications in the superolateral quadrant of her left breast, classified as highly suspicious mammographic findings (BI-RADS category 5), to be submitted to mammography-guided needle localization followed by excisional biopsy of the suspicious lesion.

A new mammography demonstrated an apparently benign nodule already present and stable in relation to the findings of the previous mammogram, besides the presence of clustered pleomorphic microcalcifications, both findings located in the superolateral quadrant of the left breast. The finding of suspicious microcalcifications drew attention for being a round-shaped cluster (Figures 1A and 1B).

Figure 1

A,B: Mediolateral oblique and craniocaudal views of left breast showing a partially calcified nodule (circle) and a cluster of pleomorphic microcalcifications (arrow) located in the superolateral quadrant of the breast. C,D: Metal clip on the dermal nevus with talc residues in its fissures, and craniocaudal view of the left breast demonstrating that the cluster of microcalcifications corresponded to talc residues.

A new assessment detected a skin nevus with irregular surface presenting with talc residues in the lesion fissures. Once the lesion was marked with a metal clip, a new mammographic image revealed that the microcalcifications corresponded to artifacts related to the talc residues present on the dermal nevus surface (Figures 1C and 1D). The mammogram was reclassified as benign mammographic findings (BI-RADS category 2) and the patient was referred for follow-up at the public basic health network.

Except for non-melanoma skin tumors, breast cancer is the most frequent neoplasm with high mortality in women in Brazil(. Mammography is the main imaging method for the early diagnosis of breast cancer; and the analysis of the differences between normal breast tissue and suspicious findings requires high imaging quality for early detection of lesions(. In addition, the presence of imaging artifacts reduces the sensitivity and specificity of imaging methods, masking or mimicking the diagnosis of initial-stage lesions and leading to the adoption os inappropriate approaches.

Most common artifacts are associated with factors related to the patient, to the imaging technique, image processing or problems in the apparatus(. The main patient-related artifacts are caused by motion during images acquisition and use of substances on the skin.

The present case illustrates the necessity of a strict mammographic image quality control and correlation with clinical findings for greater diagnostic accuracy. As already mentioned, the skin lesion led to simulation of a clustered pleomorphic microcalcifications which would imply the necessity of biopsy. The active quest for prevention and detection of artifacts, in association with a continued quality control of imaging, processing, storage and images analysis, reduces the incidence of misdiagnosis and costs, e should be the objective of any team involved in mammography services.