Granulomatous mastitis secondary to Corynebacterium kroppenstedtii.

A 37-year-old female presented with recurrent non-lactation associated left breast mastitis and abscess, despite previous aspirations and multiple 1–2-week courses of empiric antimicrobials including cephalexin, amoxicillin-clavulanate, and doxycycline. Initial aspiration cultures remained negative. On exam, she had lateral breast fullness and warmth and skin discoloration overlying a tender, mobile, fluctuant mass (Fig. 1A). Magnetic resonance imaging (MRI) showed rim enhancing lesions suggestive of abscesses in the lower outer left breast (Fig. 1B). Due to the concern for an underlying malignancy, patient underwent incision and drainage with biopsy, which revealed cystic neutrophilic granulomatous mastitis with faintly staining bacterial rods within and near the edges of small cystic spaces (Fig. 2). Subsequent cultures were positive for Corynebacterium kroppenstedtii, identified by Matrix-Assisted Laser Desorption-Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). The isolate was susceptible to tetracycline. She was diagnosed with granulomatous mastitis secondary to C. kroppenstedtii and treated with a 12-week course of doxycycline. Surgical drainage coupled with prolonged antimicrobial treatment helped resolve signs of infection. Granulomatous mastitis secondary to C. kroppenstedtii is an emerging clinical entity that should be considered in females presenting with recurrent abscesses [1]. Communication with the microbiology lab to look for and identify this organism could help in securing the diagnosis.

Fig. 1

(A) Left breast fullness and skin discoloration overlying a tender, mobile, fluctuant mass. (B) MRI of the breast showing left 2 enhancing neighboring lesions (red arrow) suggestive of abscesses in the left lower outer breast.

Fig. 2

Breast histopathology (hematoxylin and eosin; 200x original magnification) showing neutrophilic granulomatous mastitis with Gram variable organisms (black arrow) near the edges of small cystic space (1000x; inset).

Competing Interests

The authors report no competing interests.

Consent

Not applicable. Image submission. Clinical image without identifiers.

CRediT authorship contribution statement

Hussam Tabaja: Conceptualization, Writing – original draft, Writing – review & editing. Isin Yagmur Comba: Writing – review & editing, Visualization. Bobbi S. Pritt: Resources (histopathology slides), Writing – review & editing, Supervision. Omar M. Abu Saleh: Conceptualization, Writing – review & editing, Resources (clinical image), Supervision.