Granulomatous Lobular Mastitis Associated with Mycobacterium abscessus in South China: A Case Report and Review of the Literature

Granulomatous Mastitis Due to Non-Tuberculous Mycobacteria: A Diagnostic and Therapeutic Dilemma

Non-tuberculous mycobacterial (NTM) infections of the breast are rare. These infections present as cellulitis of the breast or breast abscess. Their diagnosis poses a challenge as they manifest signs of acute inflammation, unlike tuberculous mycobacterial infections which present in a chronic pattern. However, on aspiration of pus from the site of infection, primary smear may show acid fast bacilli. This poses a diagnostic dilemma. The present case is that of a 34-year-old woman who presented with recurrent mastitis. She had history of right breast swelling, for which surgical excision had been performed three months prior at another facility. Her histopathology had showed cystic granulomatous neutrophilic mastitis (CNGM). The patient again presented with right breast abscess which was confirmed on ultrasonography. Incision and drainage along with removal of necrotic tissue was done. Primary smear of pus showed acid fast bacilli on Ziehl-Neelson staining. Bacterial culture and line probe speciation revealed non-tuberculous mycobacterium M. abscessus, which responded well to prolonged anti-microbial therapy. These rapidly growing NTM require prolonged treatment and are quite often recurrent. M. abscessus is a rare cause of CNGM, with this being only the third reported case in literature. A brief case report with a review of literature is presented.

Bacteria Associated with Granulomatous Lobular Mastitis and the Potential for Personalized Therapy

Granulomatous lobular mastitis (GLM), also known as idiopathic granulomatous mastitis (IGM), is a chronic inflammatory lesion of the breast. The incidence of GLM has been increasing in recent years, especially among young women. The etiologies of GLM have not been fully elucidated but are associated with autoimmunity and bacterial infection. Bacteria, especially Corynebacterium species, play important roles in GLM. In this article, we review research progress regarding the bacteriology of GLM attained with the application of several new high-throughput detection techniques. Accurate detection might be important for deepening our understanding of the pathogenesis of GLM and hold promise for personalized GLM therapy.

Cystic neutrophilic granulomatous mastitis: an update

Cystic neutrophilic granulomatous mastitis (CNGM) is a rare subtype of granulomatous mastitis with a highly distinct histological pattern often associated with Corynebacterium species. CNGM is characterised by suppurative lipogranulomas that are composed of central lipid vacuoles rimmed by neutrophils and an outer cuff of epithelioid histiocytes. Some of the lipid vacuoles may contain sparse, rod-shaped, gram-positive bacilli that can be easily missed or dismissed. The surrounding mixed inflammatory infiltrate contains Langhans-type giant cells, lymphocytes and neutrophils. CNGM occurs in reproductive age women with a history of pregnancy and typically presents as a palpable mass that can be painful. CNGM has many mimickers, most significantly breast carcinoma. In many cases, CNGM has significant pathological and clinical overlap with other forms of granulomatous mastitis. Given the association with Corynebacterium species, early diagnosis of CNGM is essential in offering patients the most appropriate treatment. Prolonged antibiotic therapy specifically directed to corynebacteria is required, sometimes even beyond resolution of clinical symptoms. This comprehensive review of the existing literature on CNGM describes clinical-pathological features, microbiological findings, challenges associated with the microscopic differential diagnosis, clinical implications of this diagnosis and emerging treatment options. Morphological criteria and suggested comments to convey the degree of diagnostic certainty are also proposed for standard pathology reporting.