Rationale: Nocardia infection is commonly regarded as an opportunistic pulmonary pathogen affecting debilitated or immunocompromised individuals. Brain abscesses caused by Nocardia farcinica are rare and pose a diagnostic challenge. Traditional diagnostic techniques for identifying Nocardia species, such as blood culture, microscopy, and pathology, have shown inadequate performance. In the reported case, we applied metagenomic next-generation sequencing (mNGS) to diagnose a case of brain abscess due to N. farcinica. Patient concerns: A 66-year-old female developed a brain abscess after sustaining a hand injury. The patient exhibited a gradual change in personality and experienced tremors in her right upper limb for a duration of 1 month. Diagnoses: The pathogen responsible for the multiple brain abscesses was identified in the cerebrospinal fluid as N. farcinica through mNGS. Interventions: Antibiotic treatment included trimethoprim-sulfamethoxazole, linezolid, amikacin, meropenem, and moxifloxacin. Outcomes: The patient’s symptoms and signs improved significantly after administration of antibiotics to which the pathogen is known to be sensitive. After 5 months of follow-up, magnetic resonance imaging of the head showed that the abscess was basically cured. The patient lived a normal life with no adverse drug reactions. Lessons: Nocardia brain infection is characterized by an insidious onset and lacks distinctive clinical and imaging features. mNGS was advantageous for the timely identification and management of Nocardia-associated brain abscess in the present case and obviated the need for invasive brain surgery. Expeditious and precise diagnosis coupled with prompt antibiotic therapy can significantly reduce the mortality rate associated with this condition.

Rationale: Non-Hodgkin lymphoma affecting the brain, eyes, and cerebrospinal fluid without systemic spread is known as primary central nervous system lymphoma (PCNSL). While intracerebroventricular PCNSL is commonly found in the lateral ventricles and the third and fourth ventricles, the occurrence of PCNSL originating from the septum pellucidum is extremely rare. Patient Concerns: Two patients presented with recent memory loss and high cranial pressure. Diagnoses: Magnetic resonance imaging revealed a clear enhancing lesion in the septum pellucidum region. Pathological examination confirmed that both cases were primary large B-cell lymphoma GCB (germinal center B-cell-like) subtypes located in an “immune-privileged” area. Interventions: Both patients underwent total tumor resection, and the procedures were successfully completed without surgical complications. Outcomes: Over a 1-year period, treatment included four cycles of high-dose methotrexate combined with temozolomide. During the follow-up period (19–23 months), no recurrence of the lymphoma was observed. Lessons: In cases of PCNSL in the septum pellucidum, it is crucial to consider it as a potential differential diagnosis for intraventricular tumors. Surgical interventions should focus on maximizing tumor resection while ensuring the protection of critical structures like the fornix and peripheral neural components. The role of surgery compared to biopsy, as well as the long-term complications, necessitates extended follow-up. Additionally, an individualized treatment approach, considering factors such as age, Karnofsky performance score, and organ function assessment, can lead to positive outcomes.

Rationale: Primary central nervous system Burkitt lymphoma (PCNSBL) is a rare and aggressive malignancy, particularly challenging to diagnose in immunocompetent individuals due to its nonspecific presentation. Patient concerns: A 38-year-old immunocompetent woman presented with a 1-week history of progressively severe headaches in the left frontotemporal region, without systemic symptoms or significant laboratory abnormalities. Diagnoses: Advanced magnetic resonance imaging revealed a nodular lesion in the left frontal area, initially diagnosed as meningioma. Postsurgical histopathological analysis confirmed the diagnosis of Burkitt lymphoma, characterized by diffuse infiltration of medium-sized lymphocytes, a high MIB1 proliferation index, and Myc gene rearrangement. Interventions: The patient underwent complete surgical resection of the tumor and a 5-cycle chemotherapy regimen based on high-dose methotrexate, without the need for radiotherapy due to the localized nature of the tumor and complete surgical removal. Outcomes: Postoperatively, the patient’s headaches resolved, and no evidence of tumor recurrence was observed on magnetic resonance imaging after 11 months of follow-up. Additional examinations, including fluorodeoxyglucose-18–positron emission computed tomography, bone marrow biopsy, and cerebrospinal fluid cytology, confirmed the absence of systemic involvement. Lessons: This case highlights the importance of considering PCNSBL in the differential diagnosis of brain tumors, even in immunocompetent patients. Early diagnosis and a tailored chemotherapy regimen can lead to favorable treatment outcomes, emphasizing the need for a multimodality approach in managing PCNSBL.

Lymphomatoid granulomatosis (LyG) is a rare extralymphatic lymphoproliferative disease characterized by lymphocytic invasion into vascular walls and damage to blood vessels. The lungs are affected in 90% of LyG cases, followed by the skin, central nervous system (CNS), kidneys and liver. Here we report a case of a young woman with LyG, with CNS involvement as the initial clinical manifestation. Computer tomography (CT) scans showed multiple nodular, patchy and flocculent high-density shadows in both lungs without mediastinal lymph node enlargement. Magnetic resonance imaging (MRI) scans showed multiple abnormal signal intensities in the right cerebellar hemisphere, frontal, parietal and temporal lobes, and dorsal brainstem, which became patchy and annular after enhancement. The post-operative pathological analysis of lesion samples confirmed the diagnosis of grade II LyG. LyG should be concerned in young adults showing multiple radiological brain and lung lesions. Resection and postoperative medication of steroid hormones and IFN-α may be effective in the treatment of LyG.

Rationale: Erdheim-Chester disease (ECD) is a rare progressive disease affecting multiple systems. It has recently been recognized as a neoplastic disease following the discovery of activating mutations in the MAPK pathway. There are several striking signs of ECD, such as the long bone involvement, as well as the hairy kidney appearance on computed tomography scan. It is rare for ECD to manifest neurological symptoms. Central nervous system involvement is a strong prognostic factor and independent predictor of death. ECD is characterized by the overproduction and accumulation of foamy histiocytes and Touton’s giant cells in various tissues and organs. ECD is a multisystem disorder in which any organ may be affected. Patient concerns: This case report describes a 57-year-old woman with headaches and ataxia as the first clinical manifestation, without characteristic bone pain, but with delayed enuresis. In addition to the renal involvement, this patient had rarer splenic involvement. Diagnoses: The imaging presentation of this patient was similar to that of a “multiple meningiomas”. A combination of clinical, imaging and pathology for the diagnosis of ECD. Interventions: Patients were given INF-α therapy. Outcomes: Fortunately, the patient responded well to INF-α treatment. Lessons: ECD patient with neuro-endocrine symptoms.