Balamuthia mandrillaris amoebic encephalitis mimicking tuberculous meningitis.

A 76-year-old female with no apparent immunosuppressive conditions and no history of exposure to freshwater and international travel presented with headache and nausea 3 weeks before the presentation. On admission, her consciousness was E4V4V6. Cerebrospinal fluid analysis showed pleocytosis with mononuclear cell predominance, elevated protein, and decreased glucose. Despite antibiotic and antiviral therapy, her consciousness and neck stiffness gradually worsened, right eye-movement restriction appeared, and the right direct light reflex became absent. Brain magnetic resonance imaging revealed hydrocephalus in the inferior horn of the left lateral ventricle and meningeal enhancement around the brainstem and cerebellum. Tuberculous meningitis was suspected, and pyrazinamide, ethambutol, rifampicin, isoniazid, and dexamethasone were started. In addition, endoscopic biopsy was performed from the white matter around the inferior horn of the left lateral ventricle to exclude brain tumor. A brain biopsy specimen revealed eosinophilic round cytoplasm with vacuoles around blood vessels, and we diagnosed with amoebic encephalitis. We started azithromycin, flucytosine, rifampicin, and fluconazole, but her symptoms did not improve. She died 42 days after admission. In autopsy, the brain had not retained its structure due to autolysis. Hematoxylin and eosin staining of her brain biopsy specimen showed numerous amoebic cysts in the perivascular brain tissue. Analysis of the 16S ribosomal RNA region of amoebas from brain biopsy and autopsy specimens revealed a sequence consistent with Balamuthia mandrillaris. Amoebic meningoencephalitis can present with features characteristic of tuberculous meningitis, such as cranial nerve palsies, hydrocephalus, and basal meningeal enhancement. Difficulties in diagnosing amoebic meningoencephalitis are attributed to the following factors: (1) excluding tuberculous meningitis by microbial testing is difficult, (2) amoebic meningoencephalitis has low incidence and can occur without obvious exposure history, (3) invasive brain biopsy is essential in diagnosing amoebic meningoencephalitis. We should recognize the possibility of amoebic meningoencephalitis when evidence of tuberculosis meningitis cannot be demonstrated.

Thorahcic SMARCA4-deficient undifferentiated tumors with ganglioneuroma and enchondroma: implications for SLC7A11 and ARID1A expression: a case report.

BACKGROUND: SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4-deficient thoracic sarcoma (SMARCA4-DTS) is a rare disease that has recently been described as an entity. It is characterized by an aggressive clinical course and specific genetic alterations. As an immunohistological feature, the tumors are deficient in SMARCA4 and SMARCA2 and express sex-determining region Y (SRY)-box 2 (SOX2). Occasionally, there are cases that are less frequent and difficult to distinguish from SMARCA4-deficient non-small cell lung carcinoma (SMARCA4-dNSCLC). Therefore, the 5th edition of the World Health Organization (WHO) classification describes thoracic SMARCA 4-deficient undifferentiated tumors (SMARCA4-UT). In contrast, Carney's triad is a syndrome that combines three rare soft tissue tumors: gastric leiomyosarcoma, pulmonary chondroma, and extra-adrenal paraganglioma. Protein kinase cAMP-dependent type I regulatory subunit alpha (PRKAR1A) has been proposed as the causative gene. Both diseases are valuable cases; moreover, there have been no previous reports of their coexistence. CASE PRESENTATION: A 43-year-old man visited our hospital because of respiratory distress. Computed tomography revealed a large mass measuring 55 mm in the upper lobe of the right lung and front mediastinum, with metastases in the surrounding lymph nodes. Needle biopsy was performed for diagnosis, and histological examination of the samples revealed monotonous epithelioid-like cells with loose binding and sheet-form proliferation. The tumor cells had distinct nuclei with some rhabdoid-like cells. Immunohistochemical analysis revealed that the tumor cells were positive for AE1AE3, SOX2, CD34, and p53 and negative for SMARCA4 and SMARCA2. The patient died 6 months after admission, without any treatment. Autopsy revealed ganglioneuroma and enchondroma suggestive of an incomplete Carney complex. CONCLUSION: SMARCA4-UT is a rare and recently established disease. While it is difficult to diagnose, it is necessary to distinguish undifferentiated carcinoma, large cell carcinoma, Ewing sarcoma, and epithelioid sarcoma when diagnosing tumors involving the mediastinum. Moreover, cases of SMARCA4-UT with ganglioneuroma and enchondroma are very rare. We discuss and report a case of SMARCA4-UT in which we also examined ARID1A and SLC7A11expression.