Characteristics of Breast Charcoal Granuloma: A Delayed Complication Following Tattoo Localization

Abstract

Rationale and Objective: To evaluate the characteristic clinical and imaging findings of charcoal granuloma and suggest features that may differentiate charcoal granuloma from breast cancer. Materials and Methods: This retrospective study included 18 patients with a histologically confirmed breast charcoal granuloma between 2005 and 2021 at a single institution. All patients had a history of breast surgery after ultrasound (US)-guided charcoal marking. Two radiologists analyzed the radiologic findings of charcoal granulomas, including the presence of a mass or calcification; the shape, margin and density of the masses on mammography; and the location, size, shape, margin, orientation, echogenicity, vascularity, presence of an echogenic halo, and posterior acoustic shadowing on US. In cases with available follow-up images, we also investigated whether the size and shape had changed. Results: The median interval between breast surgery and the diagnosis of charcoal granuloma was 2.3 years (range, 0.7–18.3 years). Thirteen lesions (72.2%) were detected on screening images. In 11 (61.1%) cases, the surgical incision was not made in the tattooed skin area. Mammography showed positive findings in 10/15 patients, and most lesions were isodense masses (70%). There were no cases with calcification. On US, all lesions were masses and showed a taller-than-wide orientation (61.1%), round or oval shape (55.6%), and iso- or hyperechogenicity (83.3%). Echogenic halo (27.8%) and posterior acoustic shadowing (16.7%) were uncommon. On Doppler US, only four cases (22.2%) showed increased vascularity. Most were classified as BI-RADS 3 (38.9%) or 4A (50.0%). After biopsy, 12 patients had follow-up mammography and US. The size of the lesion decreased in nine cases and remained unchanged in three cases. A decrease in the lesion size after biopsy showed a negative correlation with the interval between detection on imaging and biopsy (p = 0.04). Conclusion: Charcoal granuloma is most commonly found 2–3 years after surgery and occurs more frequently when the incision site is different from the tattooed skin area. US findings of tall and round or oval masses with iso- or hyperechogenicity without increased vascularity could help to differentiate them from malignancies.