Cystic neutrophilic granulomatous mastitis: The Cleveland Clinic experience with diagnosis and management

Cystic neutrophilic granulomatous mastitis: sensitivity and specificity of 16s rRNA and Sanger sequencing for Corynebacterium spp

AIMS

Cystic neutrophilic granulomatous mastitis (CNGM) is a subtype of granulomatous mastitis (GM) associated with Corynebacterium spp infection. We aimed to analyse the prevalence of Corynebacteria in CNGM and non-CNGM cases.

METHODS

Breast specimens diagnosed as granulomatous inflammation between 2010 and 2020 were reviewed to identify a CNGM cohort and a non-CNGM cohort. Polymerase chain reaction-based identification of Corynebacteria by 16S ribosomal RNA (16S rRNA) primers, followed by confirmatory Sanger sequencing (SS), was performed on all cases. Clinical, radiological and microbiology data were retrieved from the electronic patient records.

RESULTS

Twenty-eight CNGM cases and 19 non-CNGM cases were identified. Compared with the non-CNGM cohort, patients in the CNGM cohort were more likely to be multiparous (p=0.01), breast feeding (p=0.01) and presenting with a larger breast mass (p<0.01), spontaneous drainage (p=0.05) and skin irritation (p<0.01). No significant difference in the prevalence of Corynebacteria between the cohorts (7% vs 11%, p=0.68) by microbiological culture was identified. Compared with microbiology culture, the sensitivity and specificity of each Corynebacterial detection method were 50% and 81% for Gram stain, and 25% and 100% for 16S rRNA combined with SS. Regardless of the diagnosis, patients positive for Corynebacteria were more likely to have a persistent disease (p<0.01).

CONCLUSION

CNGM presents as a large symptomatic breast mass in multiparous breastfeeding women. The importance of adequate sampling and repeated microbiology culture in conjunction with sequencing on all GM cases with persistent disease is paramount.

Pathological manifestations of granulomatous lobular mastitis

Granulomatous lobular mastitis (GLM) is a rare inflammatory breast disease with unknown etiology, characterized by non-caseous granulomatous inflammation of the lobules, which infiltrate lymphocytes, neutrophils, plasma cells, monocytes, and eosinophils may accompany. GLM is often misdiagnosed as breast cancer due to the lack of specificity in clinical and imaging examinations, and therefore histopathology is the main basis for confirming the diagnosis. This review provides an overview of the pathological features of granulomatous lobular mastitis and cystic neutrophil granulomatous mastitis (CNGM, a pathologic subtype of GLM). As well as pathologic manifestations of other breast diseases that need to be differentiated from granulomatous lobular mastitis such as breast tuberculosis, lymphocytic mastopathy/diabetic mastopathy, IgG4-related sclerosing mastitis (IgG4-RSM), nodular disease, Wegener's granulomatosis, and plasma cell mastitis. Besides, discusses GLM and CNGM, GLM and breast cancer, emphasizing that their relationship deserves further in-depth exploration. The pathogenesis of GLM has not yet been clearly articulated and needs to be further explored, pathology enables direct observation of the microscopic manifestations of the disease and contributes to further investigation of the pathogenesis.

Idiopathic Granulomatous Mastitis

Idiopathic granulomatous mastitis (IGM) is a rare, benign inflammatory disorder of the breast that is often underrecognized. The exact etiology and pathophysiology are unknown, but milk stasis is felt to play a role. Classically, this condition is noninfectious, but many cases are noted to be associated with Corynebacterium species. Most patients affected are parous women with a mean age of 35, and many have breastfed within five years of diagnosis. Patients typically present with a painful mass and symptoms of inflammation, and these features can sometimes mimic breast cancer. Biopsy is needed to make a definitive diagnosis, and noncaseating granulomas are found on core biopsy. Many patients have a waxing and waning course over a period of six months to two years. Goal of treatment is to avoid surgery given poor wound healing, high risk of recurrence, and poor cosmetic outcomes. Medical treatment is preferred and includes observation, antibiotics, steroids, and immune modulators such as methotrexate. In more recent years, topical and intralesional steroids have become the treatment of choice, with similar outcomes to oral steroids.

Inflammatory Lesions of the Breast

CONTEXT.—

Inflammatory lesions of the breast are rare but not infrequently pose problems both clinically and morphologically, particularly on needle core biopsies. These lesions range from acute inflammatory conditions to chronic lymphoplasmacytic and lymphohistiocytic to granulomatous inflammatory diseases.

OBJECTIVE.—

To provide a comprehensive overview of inflammatory lesions of the breast, with etiopathogenesis and clinical, radiologic, and pathologic features as well as differential diagnostic considerations, clinical management, and prognosis.

DATA SOURCES.—

The existing literature in the English language, including original research articles and review articles describing inflammatory lesions of the breast.

CONCLUSIONS.—

Inflammatory lesions of the breast are characterized by a wide variety of clinical, radiologic, and morphologic features. The histopathologic differential diagnosis often includes a neoplastic process requiring ancillary studies and correlation with clinical and radiologic findings. Although most specimens display nonspecific findings precluding a definitive pathologic diagnosis, pathologists have a unique opportunity to play a crucial role in identifying key histologic features suggestive of certain entities, such as cystic neutrophilic granulomatous mastitis, immunoglobulin (Ig) G4 mastitis, or squamous metaplasia of lactiferous ducts, in the right clinical and radiologic context, and thereby guiding optimal and timely clinical management. The information presented herein will be helpful to practicing anatomic pathologists and pathology trainees in becoming more familiar with specific morphologic features and overcoming differential diagnostic challenges related to pathology reporting of inflammatory lesions of the breast.

Cystic Neutrophilic Granulomatous Mastitis Treatment with Consecutive Dapsone and Adalimumab

Cystic neutrophilic granulomatous mastitis is a rarely reported, benign, mastitis that is not associated with lactation. The pathophysiology is still unknown; however, there is often a relationship with Corynebacterium kroppenstedtii. Cystic neutrophilic mastitis can have deep seated tender nodules and cutaneous ulceration which can clinically resemble pyoderma gangrenous. It can be treatment refractory and can progress to a point where mastectomy is required. This case series reports two patients treated with adalimumab with remission of disease. One patient first received dapsone with remission of symptoms, but incompatible side effects resulted in discontinuation. Both dapsone and adalimumab appear to provide disease remission in patients with cystic neutrophilic granulomatous mastitis.

Further Characterization of Clinicopathologic Features of Cystic Neutrophilic Granulomatous Mastitis

OBJECTIVES

Clinical and demographic features of cystic neutrophilic granulomatous mastitis (CNGM) have not been fully explored due to the rarity of the disease. Herein we studied clinicopathologic characteristics of CNGM in a sizable hospital-based cohort.

METHODS

A case-control study was performed to compare clinicopathologic characteristics between patients with CNGM and granulomatous mastitis other than CNGM and between CNGM with and without Corynebacterium identification.

RESULTS

Cases of CNGM (n = 31) and non-CNGM (n = 30) were included. Compared with the non-CNGM group, patients with CNGM were statistically significantly younger (median age: 38 vs 43 years), were less likely to be smokers (9% vs 40%), were more likely to have a painful lesion (97% vs 77%) or a larger mass-like lesion (median size: 4.6 vs 1.9 cm), and tended to have a higher Breast Imaging Reporting and Data System score in radiologic studies (score ≥4: 81% vs 53%), positive Corynebacterium identification results (36% vs 0%), and a longer resolving time (12 vs 6 months; all P values for above comparisons <.05). Among CNGM cases, patients with and without Corynebacterium identification shared a similar clinicopathologic profile.

CONCLUSIONS

Our study further demonstrated that CNGM is a unique infectious disease with distinct clinicopathologic features.

Management of granulomatous lobular mastitis: an international multidisciplinary consensus (2021 edition)

Granulomatous lobular mastitis (GLM) is a rare and chronic benign inflammatory disease of the breast. Difficulties exist in the management of GLM for many front-line surgeons and medical specialists who care for patients with inflammatory disorders of the breast. This consensus is summarized to establish evidence-based recommendations for the management of GLM. Literature was reviewed using PubMed from January 1, 1971 to July 31, 2020. Sixty-six international experienced multidisciplinary experts from 11 countries or regions were invited to review the evidence. Levels of evidence were determined using the American College of Physicians grading system, and recommendations were discussed until consensus. Experts discussed and concluded 30 recommendations on historical definitions, etiology and predisposing factors, diagnosis criteria, treatment, clinical stages, relapse and recurrence of GLM. GLM was recommended as a widely accepted definition. In addition, this consensus introduced a new clinical stages and management algorithm for GLM to provide individual treatment strategies. In conclusion, diagnosis of GLM depends on a combination of history, clinical manifestations, imaging examinations, laboratory examinations and pathology. The approach to treatment of GLM should be applied according to the different clinical stage of GLM. This evidence-based consensus would be valuable to assist front-line surgeons and medical specialists in the optimal management of GLM.

Idiopathic granulomatous mastitis: case series and clinical review

Idiopathic granulomatous mastitis is a chronic inflammatory breast disorder that typically affects young, parous women, often following lactation. Patients present with tender, erythematous breast lesions with histological evidence of non-caseating granulomata and an inflammatory cell infiltrate. An immune-mediated pathophysiology is hypothesised and an association with lipophilic Corynebacterium species is observed. Initial diagnosis is often delayed due to lack of awareness of the condition and management of refractory disease can be challenging. We present an extensive case series of patients collaboratively managed by subspecialty physicians and surgeons at a single centre in Sydney, Australia. The accompanying review expands on features of this condition and supports the utility of a multidisciplinary approach.

Detection of Corynebacterium kroppenstedtii in Granulomatous Lobular Mastitis Using Real-Time Polymerase Chain Reaction and Sanger Sequencing on Formalin-Fixed, Paraffin-Embedded Tissues

CONTEXT.—

Associations between granulomatous lobular mastitis (GLM) and Corynebacterium kroppenstedtii have been reported since 2002, but large scale studies to assess the actual prevalence of this bacterium in GLM have not been performed.

OBJECTIVE.—

To assess the prevalence of C kroppenstedtii in GLM using real-time polymerase chain reaction and Sanger sequencing.

DESIGN.—

We analyzed formalin-fixed, paraffin-embedded tissues from 67 cases of GLM by sequential DNA amplification and sequencing to assess the rate of C kroppenstedtii detection in GLM. A retrospective analysis including patient demographics, history of pregnancy and lactation, clinical signs and symptoms, radiographic findings, histologic pattern, Gram stain results, and microbial cultures was performed on 67 cases of GLM. In addition, 10 cases of nongranulomatous breast abscess were included as controls.

RESULTS.—

C kroppenstedtii 16S rRNA SYBR real-time polymerase chain reaction was positive on formalin-fixed, paraffin-embedded tissues from 46 of 67 (68.7%) GLM cases, while all control cases were negative. Among the positive cases, the majority showed features of cystic neutrophilic granulomatous mastitis.

CONCLUSIONS.—

C kroppenstedtii was highly prevalent in GLM cases and was not found to be associated with nongranulomatous breast abscess in our study (P < .001).

New Insights of Corynebacterium kroppenstedtii in Granulomatous Lobular Mastitis based on Nanopore Sequencing

BACKGROUND

The etiology of granulomatous lobular mastitis (GLM) remains unknown. This study aimed to detect bacteria in GLM using Nanopore sequencing and identify the relationship between GLM and Corynebacterium kroppenstedtii.

METHODS AND MATERIALS

The bacterial detection on fresh samples (including breast pus and tissue) of 50 GLM patients using nanopore sequencing and culture methods. The bacterial detection rate of participants with different stages were compared and analyzed. Formalin-fixed and paraffin-embedded (FFPE) tissues from 39 patients were performed on Gram staining to identify Gram-positive bacilli (GPB) within lipid vacuoles. Moreover, the clinicopathological characteristics of GLM patients in different bacterial subgroups were also conducted.

RESULTS

In 50 GLM patients, the detection rate of bacteria was 78% using nanopore sequencing method, especially in the early stage of GLM (over 80%), which was significantly higher than that using culture methods (24%, p < 0.001). The dominant bacteria were Corynebacterium species (64%), especially for the Corynebacterium kroppenstedtii. The detection rate of C. kroppenstedtii in nanopore sequencing method (56%) was higher than that in culture methods (16%, p < 0.001). Gram staining positive of bacteria in 7 patients, and 5 of them were C. kroppenstedtii. Thirty-one patients (31/39, 79.5%) exhibited typical histological structure of cystic neutrophilic granulomatous mastitis (CNGM), and eighteen patients detected with C. kroppenstedtii.

CONCLUSION

Nanopore sequencing showed rapid and accurate bacteria detection over culture method in GLM patients. GLM is not sterile inflammation and closely related to C. kroppenstedtii. CNGM was associated with Corynebacterium infection, especially for C. kroppenstedtii.

Idiopathic Granulomatous Mastitis of the Breast: Radiologic-Pathologic Correlation

Granulomatous inflammation is an uncommon inflammatory condition of the breast that includes both infectious (bacterial, fungal, parasitic) and noninfectious (autoimmune, sarcoidosis, idiopathic granulomatous mastitis [IGM], reaction to foreign materials) etiologies. IGM is the most common subset of granulomatous inflammation where no underlying etiology is established. Infectious causes of granulomatous inflammation should be excluded, as these have established treatments that can significantly improve patient outcomes. IGM should be considered in the differential when mastitis is refractory to antibiotics. Patients usually present with an erythematous, tender, palpable unilateral breast mass. The most common mammographic presentation is a focal or global asymmetry. The imaging appearance mimics breast cancer, therefore diagnosis usually requires tissue sampling with histopathologic analysis and cultures to exclude infection. When patients are diagnosed with IGM, this poses a clinical dilemma as there are a variety of treatment options available, including oral and intralesional steroids. The time course of the disease is often prolonged by multiple recurrences, and specific treatment remains an area of ongoing research. The purpose of this article is to review the range of clinical features, imaging manifestations, associated histopathology, and management of IGM.

Whole genome sequence of Corynebacterium kroppenstedtii isolated from a case of recurrent granulomatous mastitis

We describe the case of a 33-year-old woman with recurrent granulomatous mastitis associated with Corynebacterium kroppenstedtii. This organism has been increasingly associated with granulomatous mastitis, specifically the cystic neutrophilic histopathologic variant, although currently there is a paucity both of reported cases and genomic sequence data. We highlight the challenges in the diagnosis and treatment of this entity, in particular focusing on the various methods of microbiologic identification, including MALDI-TOF, 16 s rRNA PCR and whole-genome sequencing.

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 during chemotherapy treatment for invasive breast carcinoma – a rare lesion that simulates tumor progression

Background

Cystic neutrophilic granulomatous mastitis (CNGM) is an uncommon and recently described pattern of granulomatous mastitis. To our knowledge, no cases have been described during chemotherapy for invasive breast cancer.

Case presentation

A 42-year-old female patient had a diagnosis of invasive breast carcinoma (3-cm nodule). During neoadjuvant chemotherapy, she presented with an enlargement of the breast nodule that measured 7.0-cm on palpation. The lesion did not show typical inflammatory clinical findings and simulated tumor progression. A core biopsy showed granulomas with pseudocystic spaces with gram-positive bacilli (Corynebacterium sp.), and numerous circumjacent neutrophils. She was treated with antibiotics and resumed chemotherapy. Surgical specimen showed a 1.0-cm residual carcinoma and extensive xanthogranulomatous inflammation with no evidence of residual CNGM.

Conclusion

CNGM is usually associated with typical clinical presentation of mastitis. It is an important pattern of granulomatous inflammation to be recognized in the breast since it directly impacts treatment. The present case highlights its potential occurrence during chemotherapy treatment of breast cancer mimicking progression of breast malignancy.

Cystic neutrophilic granulomatous mastitis - a review of 12 consecutive cases

AIMS

Cystic neutrophilic granulomatous mastitis (CNGM) is an uncommon but increasingly recognised cause of mastitis, often associated with Corynebacterium ssp. infection. We studied the histopathological and clinical features of CNGM in a Canadian setting, and the work-up required to identify pathogenic microorganisms.

METHODS AND RESULTS

A retrospective search for breast specimens with abscess, acute, chronic and/or granulomatous inflammation from 1998 to 2018 was performed. Haematoxylin and eosin slides were reviewed for typical histological features of CNGM. Histochemically stained slides for microorganisms were also reviewed. Repeat Gram stains were performed if initially negative. Electronic medical records were abstracted for microbiology results and relevant clinical data. Twelve cases were identified. All were female, aged 25-57 years, mainly Caucasian, with one Venezuelan and two of Chinese ethnicity. Most were parous (10 of 12); five of 12 had an endocrinopathy. Bacteria were identified in one or more specimens from eight of 12 patients; additional Gram stains revealed organisms in four of 12 cases. Of four bacterial cultures, one grew Corynebacterium kroppenstedtii. 16S polymerase chain reaction for three samples was negative. Two patients had multiple breast biopsies, showing early palisaded granulomas followed by classic features of CNGM. The patients had various management approaches, including surgery and antimicrobials.

CONCLUSIONS

CNGM may present as palisaded granulomatous inflammation, without the expected 'cystic' pattern, suggesting that there is an evolution of histomorphology with this infection. Most patients with CNGM are parous, and there may be an association with endocrinopathies. Application of multiple Gram stains increases the yield of microorganism identification. Recognition of CNGM in breast biopsies and collaborative communications are essential to direct appropriate therapy.

A Novel First-Line Treatment Alternative for Noncomplicated Idiopathic Granulomatous Mastitis: Combined İntralesional Steroid İnjection with Topical Steroid Administration

Background

Idiopathic granulomatous mastitis (IGM) is a rare form of nonlactational mastitis. Due to the small number of case series and consequently inadequate prospective studies, there is still no consensus on the optimal treatment of IGM. In this study, we aimed to compare the efficacy of intralesional steroid injection with concomitant topical steroids to systemic steroid therapy only in the treatment of noncomplicated IGM.

Methods

Between June 2015 and April 2018, the patients' data was prospectively collected and analyzed retrospectively. The study included a total of 78 female patients diagnosed with IGM. Patients were divided into 2 groups: the local steroid treatment group (intralesional steroid injection with topical steroid administration; group 1, n = 46) and the peroral systemic steroid treatment group (group 2, n = 32). Response to the therapy, side effects, recurrence, the need for surgical treatment, and complication rates were compared.

Results

Forty-three patients (93.5%) in group 1 achieved a partial or complete response compared to 23 patients (71.9%) in group 2 after 3 months; this difference was significant (p = 0.012). The recurrence rates were significantly lower in group 1 (8.7%) compared to group 2 (46.9%; p = 0.001), and the need for surgical treatment was significantly less in group 1 (2.2%) than in group 2 (9.4%; p = 0.001). While the complication rates were similar between groups, a higher rate of systemic side effects was observed in group 2.

Conclusion

Based on the results of our study, combined steroid injection and topical steroid treatment in IGM is as effective as systemic steroid treatment. We suggest that this combination therapy of topical steroids and local steroid injection should be used as first-line therapy in patients with noncomplicated IGM.

"Thick Section" Gram Stain Yields Improved Detection of Organisms in Tissue Sections of Cystic Neutrophilic Granulomatous Mastitis

OBJECTIVES

Cystic neutrophilic granulomatous mastitis (CNGM) is an uncommon subtype of granulomatous mastitis featuring epithelioid histiocytes/neutrophils rimming discrete cystic spaces. When present, gram-positive bacteria (typically Corynebacterium species) are identified within these cystic spaces, although they can be difficult to appreciate on tissue sections.

METHODS

Based on pilot gram-stained tissue sections of CNGM cases cut on 6 μm thickness (in which bacterial organisms were more readily identifiable) instead of the traditional 4 μm, a formal comparative analysis of 19 CNGM cases was performed on parallel 6-μm ("thick") vs 4-μm sections from one representative block per case.

RESULTS

Biopsies (n = 17) and excisional specimens (n = 2) from 19 CNGM cases were included. Gram-positive palisaded rods were identified in seven cases using 4-μm sections and in 11 cases using 6-μm sections (sensitivity of 37% vs 58% in identifying organisms). Among all seven cases of organisms seen on the 4-μm section Gram stain, the paired 6-μm section Gram stain showed a higher number of and more readily identifiable bacteria.

CONCLUSIONS

Thick section Gram stain of representative tissue blocks performed at 6 μm improves both detection rate and ease of identification of gram-positive organisms in CNGM.

A systematic surgical approach for the treatment of idiopathic granulomatous mastitis: a case series

Background

Surgical resection can be performed for idiopathic granulomatous mastitis (IGM), but recurrence and tissue defects remain issues. Here we report our 6-year experience with a four-pattern surgical approach for IGM that involves the use of a random breast dermo-glandular flap (BDGF).

Methods

Sixty-eight consecutive patients with IGM were prospectively enrolled from 01/2012 and 03/2017. Based on the extent, shape, and location of the lesions, four different patterns of surgery based on BDGF were used to remove the lesion and repair the defect. Operative data (time, blood loss, and intraoperative complications), primary healing time, recurrence, and patient-reported outcomes (cosmetic outcome, and improvement in dressing change and bathing) at 2 years were evaluated.

Results

Patients' median age was 35 (range, 22-55) years. Duration of IGM was 3-22 months, with a median lesion size of 3.5 (range, 0.9-9.1) cm. The operative time was significantly longer, and blood loss was more important with the increasing lesion size (both P<0.05). No significant intraoperative complications occurred. All wounds healed by primary intention. IGM relapsed in three patients (3/68, 4.4%); they were treated successfully with a second operation. The self-evaluated cosmetic outcome was "much better" in 45 patients (66.2%), "a little better" in 18 (26.5%), and "same or worse" in five (7.3%). The self-evaluated improvement in dressing change and bathing was "improved a lot" in 51 patients (75.0%), "improved a little" in 11 (16.2%), and "not improved or getting worse" in six (8.8%).

Conclusions

The BDGF-based systematic four-pattern surgical approach is effective in the treatment of IGM. Recurrence rate is low, there are no complications, and the cosmetic results and improvement in dressing change and bathing are generally favourable.

Mastitis in Autoimmune Diseases: Review of the Literature, Diagnostic Pathway, and Pathophysiological Key Players

Mastitis frequently affects women of childbearing age. Of all the pathological breast conditions requiring specific management, autoimmune mastitis is in the third position after infection and breast cancer. The aim of this literature review was to make a comprehensive description of autoimmune diseases targeting the mammary gland. Four main histological patterns of autoimmune mastitis are described: (i) lymphocytic infiltrates; (ii) ductal ectasia; (iii) granulomatous mastitis; and (iv) vasculitis. Our literature search found that all types of autoimmune disease may target the mammary gland: organ-specific diseases (diabetes, thyroiditis); connective tissue diseases (such as systemic erythematosus lupus or Sjögren’s syndrome); vasculitides (granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, giant cell arteritis, polyarteritis nodosa, Behçet’s disease); granulomatous diseases (sarcoidosis, Crohn’s disease); and IgG4-related disease. Cases of breast-specific autoimmune diseases have also been reported, including idiopathic granulomatous mastitis. These breast-limited inflammatory diseases are sometimes the first symptom of a systemic autoimmune disease. Although autoimmune mastitis is rare, it is probably underdiagnosed or misdiagnosed. Early diagnosis may allow us to detect systemic diseases at an earlier stage, which could help to initiate a prompt, appropriate therapeutic strategy. In case of suspected autoimmune mastitis, we hereby propose a diagnostic pathway and discuss the potential pathophysiological pathways leading to autoimmune breast damage.

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.

The Role of Establishing a Multidisciplinary Team for Idiopathic Granulomatous Mastitis in Improving Patient Outcomes and Spreading Awareness about Recent Disease Trends

Background

Iidiopathic granulomatous mastitis (IGM) is stereotypically described as a mysterious entity that mimics breast carcinoma imposing management challenges. In 2002, we established a multidisciplinary team to treat patients with IGM. This study aimed to evaluate the role of this team in improving patient outcomes. Also, a review of literature is provided to highlight recent disease trends. Patients and Methods. Pertinent data for 44 patients treated for IGM from 2002 to 2018 were analyzed and compared to data prior to 2002.

Results

Mean age at diagnosis was 37.9 years ± 6.4. The diagnosis of IGM was confirmed by True-cut biopsy (TCB), Frozen section (FS), and surgical biopsy in 70.5%, 25%, and 4.5% of patients, respectively. FS was used to assess the resection margins in three patients. Suspicion for malignancy was raised in one out of 39 ultrasound reports, and one out of 20 mammography reports. Wide local excision was the main treatment modality (95.5%). 19 patients (43.2%) received corticosteroids. Prior to 2002, IGM was only recognized after surgical resection with a 71% initial false impression of carcinoma. After 2002, the initial false clinical impression of carcinoma dropped to 29.5%. Recurrence rate was 31.82%. Younger age at diagnosis was significantly associated with recurrence (χ ² = 5.598; p = 0.018). Chi-square analysis showed no significant association between BMI and recurrence (χ ² = 0.776; p = 0.678).

Conclusion

The establishment of a multidisciplinary team for IGM was associated with a reduced erroneous impression of breast cancer, and a reduced false positive radiological diagnosis of breast carcinoma. FS was a useful confirmatory procedure. Our series included the first case of a diffuse papular rash as a systemic manifestation of IGM. Recent literature indicates that IGM is changing its face. IGM is being reported in all age groups, and even in males. The clinical manifestations have markedly expanded. Diagnosis by TCB has replaced blind surgical excision. More data regarding predictors of recurrence is accumulating.

Cystic Neutrophilic Granulomatous Mastitis: A Clinicopathological Study With 16s rRNA Sequencing for the Detection of Corynebacteria in Formalin-Fixed Paraffin-Embedded Tissue

Cystic neutrophilic granulomatous mastitis (CNGM) is a histologically characterized variant of granulomatous lobular mastitis that is associated with lipophilic Corynebacterium species. It remains a largely underrecognized entity in India. Our aim was to study CNGM in the Asian Indian population and explore if 16s rRNA sequencing could be used on formalin-fixed paraffin-embedded (FFPE) tissue to identify the causative organism. We studied 24 cases with histological features of CNGM with hematoxylin and eosin, Gram, Ziehl-Neelsen, and Periodic acid-Schiff stains. Tuberculosis-polymerase chain reaction and 16s rRNA gene sequencing on DNA extracted from FFPE was attempted (N = 23). Gram-positive bacilli were seen in 20/24 cases. Routine culture with prolonged incubation yielded Corynebacterium species in 8 cases; 7 of these cases were evaluated by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for species identification. C matruchotti was identified in one case by BD Phoenix. MALDI-TOF MS identified the remaining 7 cases as C kroppenstedtii (N = 4) and C tuberculostearicum (N = 2), with no identification in one. Corynebacteria were identified by 16s rRNA sequencing on DNA extracted from FFPE in 12/23 cases using a primer targeting the V5-V6 region that was found to be more conserved in Corynebacterium species. All cases were negative for the diagnosis of tuberculosis. CNGM can be identified by routine stains. Culture using routine media with prolonged incubation is often adequate to isolate the organism. 16s rRNA sequencing on DNA extracted from FFPE tissue can help make an etiological diagnosis in some cases where only paraffin blocks are available.