A 36-year-old woman with a unilateral breast mass. Necrotizing granulomatous mastitis secondary to budding yeast forms morphologically consistent with Histoplasma capsulatum

Cat Scratch Disease of the Breast/Axilla: Recognition of a Rare Disease and Approaches for Differential Diagnosis

Cat scratch disease rarely presents as a breast or axillary mass mimicking carcinoma both clinically and radiologically. Diagnosing breast/axillary cat scratch disease is challenging due to its rarity and nonspecific findings. Here, we reported 2 patients with breast cat scratch disease and reviewed 14 patients with cat scratch disease involving breast/axilla from the past 30 years. It mainly affects women (median age: 48), consistently presenting as axillary lymphadenopathy, and demonstrates ipsilateral breast mass in half of patients (50%, 8/16). The breast mass was most commonly located in the upper outer quadrant (88%, 7/8), indicating the possibility of disease extension from axillary adenopathy. Around half of patients (56%, 9/16) reported cat exposure. Histologically, most patients (93%, 14/15) presented as necrotizing granulomas, with characteristic stellate-shaped necrosis in 5 patients. Although pathologic differential diagnoses between cat scratch disease and cancer are straightforward, distinguishing cat scratch disease from other granulomatous mastitis poses diagnostic challenges. Silver stains should be included in the diagnostic workup panel when highly suspecting cat scratch disease clinically. However, they were only able to highlight the causative microorganism in 54% (7/18) patients, and the gram stain was negative in all 12 tested patients. In contrast, polymerase chain reaction (PCR) for the causative microorganism was consistently positive in all 3 tested patients, while serologic test confirmed diagnosis in 85% (11/13) patients; 1 patient with negative serology showed a positive PCR result. Therefore, upfront PCR tests with or without serologic study should be considered to confirm the diagnosis of cat scratch disease in a timely manner.

Non-lactational Infectious Mastitis in the Americas: A Systematic Review

Background: Non-lactational infectious mastitis (NLIM) is an inflammatory breast disease with broad clinical presentation. Inadequate treatment can lead to chronic infections that cause breast deformities. NLIM information is limited, especially in the Americas. A systematic review and meta-analysis have been conducted here. Methods: Literature search was conducted in three databases (Lilacs, PubMed, and Scielo) on NLIM cases in the Americas. Demographic, epidemiological, clinical, radiological, and laboratory data were extracted. The main characteristics and results were also compared according to the country's gross national income. Results: A total of 47 articles were included, resulting in 93 cases. The etiological agent was described in 86 (92.5%) patients. Bacteria were the most prevalent etiology (73; 84.8%). Amongst bacterial diagnoses, more frequent cases were Mycobacterium tuberculosis (28; 38.4%); Corynebacterium spp. (15; 20.5%); non-tuberculous mycobacteria (13; 17.8%). The cases were reported in eight different countries, with the USA being the country with the highest number of cases (35; 37.6%). Patients from high-income countries group presented a shorter diagnostic time when compared to low, low-middle, and upper-middle-income countries. A greater number of radiographic studies with pathological findings were described in high-income countries. Conclusion: Non-lactational infectious mastitis is a complex public health problem with diagnostic and treatment challenges. Hence, multi-professional approach-based additional studies are recommended on its epidemiology, diagnosis, treatment, and control.

Idiopathic granulomatous lobular mastitis

Idiopathic granulomatous lobular mastitis (IGLM) is a rare breast condition with prominent skin findings. It is typically seen in young parous women. Painful breast masses, draining sinuses, scarring, and breast atrophy are the main clinical manifestations. IGLM can resemble a variety of other inflammatory and neoplastic processes of the breast. It is thought to result from obstruction and rupture of breast lobules. Extravasated breast secretions then induce an inflammatory reaction. Corynebacteria have also been implicated in the pathogenesis. Treatment is surgical, but systemic corticosteroids, methotrexate, and antibiotics also play a role.

A human immunodeficiency virus-positive infant with probable congenital histoplasmosis in a nonendemic area

A 5-week-old infant presented with a fever, and was diagnosed with congenital human immunodeficiency virus and histoplasmosis. Both infections were likely transmitted vertically. The child was effectively treated with antifungal medications and highly active antiretroviral therapy. This represents the first case of delayed presentation of vertically transmitted histoplasmosis, and the first case in a nonendemic area.