Idiopathic Chronic Granulomatous Mastitis

Clinical History

The patient was sent from the Gynecology service with a palpable mass in the left breast. Personal history revealed childbirth three months ago and breastfeeding since then. Ultrasound examination was performed followed by ultrasound-guided core-biopsy and mammography. Steroid therapy was completed. Two years later, she consulted for a tenderness palpable mass in the same location.

Imaging Findings

In the first episode, sonography showed a hypo-echoic and irregular mass with tubular extension in the upper outer left quadrant, regarding the palpable lesion (Fig. 1a). Associated hypo-echoic abnormal lymph nodes were seen in the left axilla (Fig. 1b). Mammogram revealed a focal asymmetry in the upper outer quadrant of the left breast (Fig 2). US-guided core-needle biopsy was performed to reach a diagnosis and exclude malignancy (Fig. 3 and Fig. 4). Finally, she improved with steroid therapy (Fig. 5) and the ultrasound examination returned normal.

Two years later, ultrasound examination depicted a hypo-echoic, heterogeneous and round mass in the same location, regarding the new breast lump (Fig. 6). US-guided core-needle biopsy was performed again and histo-pathologic analysis confirmed the recurrence.

Discussion

Granulomatous lobular mastitis is a rare condition characterized by chronic, noninfectious and noncaseating granulomatous lobular inflammation of the breast. The pathophysiology of this disease is still unknown, although autoimmune aetiology has been suggested [1-4].

It occurs in women of childbearing age, typically with personal history of recent lactation, [1, 3, 4]. The main symptom is a unilateral tender mass that can associate skin thickening, erythema and ulceration, nipple discharge and axillary adenopathy [1, 4].

The diagnosis is based on exclusion [2], combining radiologic and pathologic evaluation [4].
Mammographic appearance is variable [1, 2]. The most frequent presentation is high-density fibroglandular parenchyma with a focal asymmetry [1-3], followed by multiple high-density nodules with ill-defined borders. Furthermore, skin thickening and axillar lymph nodes can be seen [1-3].

Sonography depicts an irregularly shaped heterogeneous mass with ill-delimited margins and tubular extension [1, 3], associated with a striated echo-texture of the breast [3].

RM is reserved for doubtful cases. It demonstrates a non-mass enhancement accompanied by ring-enhancing lesions in T1 post-contrast weighted images [3].

Finally, pathological evaluation is necessary. Ultrasound guided biopsy is recommended [1-3] instead of FNAB [1, 3]. Microscopic features include avascular [2], noninfective and nonnecrotizing granulomas centered on lobules [1, 2] with micro-abscesses [3, 4] and exclude other granulomatous reactions [2, 4].

Treatment is in discussion [4], including excisional biopsy [2], steroid therapy [1] and expectant management [3]. Recurrence is a well-known complication. Therefore, follow up is needed [3].

Differential Diagnosis List

Final Diagnosis

Idiopathic chronic granulomatous mastitis

URL:	https://www.eurorad.org/case/14200
DOI:	10.1594/EURORAD/CASE.14200
ISSN:	1563-4086