Polymicrobial brain abscesses: A complex condition with diagnostic and therapeutic challenges.

Brain abscesses (BA) are focal parenchymal infections that remain life-threatening conditions. Polymicrobial BAs (PBAs) are complex coinfections of bacteria or bacterial and nonbacterial pathogens such as fungi or parasites, with diagnostic and therapeutic challenges. In this article, we comprehensively review the prevalence, pathogenesis, clinical manifestations, and microbiological, histopathological, and radiological features of PBAs, as well as treatment and prognosis. While PBAs and monomicrobial BAs have some similarities such as nonspecific clinical presentations, PBAs are more complex in their pathogenesis, pathological, and imaging presentations. The diagnostic challenges of PBAs include nonspecific imaging features at early stages and difficulties in identification of some pathogens by routine techniques without the use of molecular analysis. Imaging of late-stage PBAs demonstrates increased heterogeneity within lesions, which corresponds to variable histopathological features depending on the dominant pathogen-induced changes in different areas. This heterogeneity is particularly marked in cases of coinfections with nonbacterial pathogens such as Toxoplasma gondii. Therapeutic challenges in the management of PBAs include initial medical therapy for possibly underrecognized coinfections prior to identification of multiple pathogens and subsequent broad-spectrum antimicrobial therapy to eradicate identified pathogens. PBAs deserve more awareness to facilitate prompt and appropriate treatment.

Clinicopathologic characteristics of Nocardia brain abscesses: Necrotic and non-necrotic foci of various stages.

Nocardia brain abscesses are rare bacterial infections associated with a high mortality rate, and their preoperative diagnosis can be difficult for various reasons including a nonspecific clinical presentation. While late-stage nocardial brain abscesses may be radiologically characteristic, early-stage lesions are nonspecific and indistinguishable from another inflammatory/infectious process and other mimics. Despite the paucity of previous histopathological descriptions, histopathological examination is critical for the identification of the pathogen, lesion stage(s), and possible coexisting pathology. In this study, we examined the clinical, radiological and histopathological features of 10 patients with brain nocardiosis. Microscopic findings were analysed in correlation with clinical and radiological features in 9 patients, which revealed that brain nocardiosis was characterized by numerous necrotic and non-necrotic foci of various stages (I-IV) along with Nocardia identification, as well as the leptomeningeal involvement in most cases, and co-infection of brain nocardiosis with toxoplasmosis in 2 patients. The imaging features were characteristic with a multilobulated/bilobed ring-enhancing appearance in 8 patients including 2 patients with multiple lobulated and non-lobulated lesions and 1 patient showing the progression from a non-lobulated to lobulated lesion. These findings suggest that nocardial brain abscesses particularly at late-stages share common characteristics. Nevertheless, given the complex pathologic features, including possible co-infection by other pathogens, nocardial brain abscesses remain a therapeutic challenge.

Merkel Cell Carcinoma of the Head and Neck.

Merkel cell carcinoma (MCC) of the head and neck is a rare and aggressive non-melanoma skin cancer. The objective of this study was to assess the oncological outcome of MCC by retrospective review of electronic and paper records of a population-based cohort of 17 consecutive cases of the head and neck MCC without distant metastasis, diagnosed in Manitoba between 2004 and 2016. The average age of the patients at initial presentation was 74.1 ± 14.4 years with 6 patients presenting with stage I, 4 with stage II, and 7 with stage III disease. Both surgery or radiotherapy alone were the primary treatment modalities in 4 patients each and the remaining 9 patients had a combination of surgery with adjuvant radiotherapy. During the median follow-up of 52 months, 8 patients had recurrent/residual disease and 7 eventually died of it (P = .001). Metastatic spread of disease to the regional lymph nodes was observed in 11 patients either at presentation or during the follow-up and to the distant sites in 3 patients. At the time of the last contact on November 30, 2020, 4 patients were alive and disease-free, 7 had died of disease, and 6 had died of other causes. The case fatality rate was 41.2%. Five-year disease-free and disease-specific survivals were 51.8% and 59.7%, respectively. The 5-year disease-specific survival was 75% for early stage MCC (stage I and II) and 35.7% for stage III MCC. Early diagnosis and intervention are crucial for disease control and improving survival.

Le carcinome à cellules de Merkel (CCM) de la tête et du cou est un cancer de la peau non mélanique rare et virulent. La présente étude visait à évaluer le pronostic oncologique du CCM par une analyse rétrospective des dossiers électroniques et papier d'une cohorte en population de 17 cas consécutifs de CCM de la tête et du cou sans métastases distantes, diagnostiqués au Manitoba entre 2004 et 2016. Les patients avaient un âge moyen de 74,1±14,4 ans à la première consultation. Six d'entre eux étaient atteints d'un cancer de stade I, quatre d'un cancer de stade II et sept, d'un cancer de stade III. La chirurgie était la modalité thérapeutique primaire chez quatre patients, la radiothérapie, chez quatre autres, et les neuf derniers ont reçu une combinaison de chirurgie et de radiothérapie adjuvante. Pendant le suivi médian de 52 mois, huit patients ont souffert d'une récurrence ou d'une maladie résiduelle, et sept ont fini par en mourir (p=0,001). Onze patients ont présenté une propagation métastatique aux ganglions lymphatiques soit à la présentation, soit pendant le suivi, et trois en ont souffert à un siège distant. Au moment du dernier contact, le 30 novembre 2020, quatre patients étaient vivants et exempts de maladie, sept étaient décédés de la maladie et six étaient décédés d'autres causes, pour un taux de létalité de 41,2 %. La survie exempte de toute maladie et de cette maladie au bout de cinq ans s'élevait à 51,8 % et à 59,7 %, respectivement. La survie exempte de cette maladie au bout de cinq ans s'élevait à 75 % pour le CCM des stades I et II, et à 35,7 % pour le CCM de stade III. Il est essentiel de poser le diagnostic et d'intervenir rapidement pour contrôler la maladie et accroître la survie.