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Methemoglobinemia is a potentially life-threatening condition caused by the formation of methemoglobin, a form of hemoglobin that cannot bind oxygen. While there are some rare congenital causes of methemoglobinemia, most cases are acquired from the effects of specific drugs or environmental exposures. In this retrospective study, we analyzed a large data set of whole blood samples analyzed for methemoglobin at an academic medical center in Midwestern United States that provides both pediatric and adult services. For a 14 year timeframe (May 2009- June 2023), we performed detailed chart analysis of all patients with a methemoglobin concentration of 3.1 % or higher. For an earlier 13 year timeframe (January 1996-April 2009), we performed chart review for all patients with a methemoglobin concentration of 10.0 % or higher. For the 2009-2023 data, dapsone was the most frequent cause of methemoglobinemia (methemoglobin 3.1 % or higher) in both pediatric (73.3 %, 115 clinical encounters, 105 unique patients) and adult (65.3 %, 195 clinical encounters, 190 unique patients) populations. Inhaled nitric oxide as medical therapy was the next most frequent cause in both pediatric (18.1 %) and adult (13.2 %) populations. Causes associated with two or more unique episodes with methemoglobin concentrations of 10.0 % and higher included the following: dapsone (n = 40 episodes), benzocaine (n = 10), recreational use of amyl or isobutyl nitrite (n = 3), suicide attempt with sodium nitrite (n = 3 with 1 fatality; all 3 cases within last 3 years), food contaminated with nitrates (n = 2), and sepsis (n = 2). A total of 18 patients received treatment with methylene blue including 5 cases associated with benzocaine and all of the cases associated with amyl nitrite, isobutyl nitrite, sodium nitrite, and contaminated food. Only 3 patients with dapsone-associated methemoglobinemia received methylene blue, reflecting primary management by dose reduction or discontinuation of drug. Overall, our data reinforce previous studies showing dapsone, inhaled nitric oxide, and nitrites as common agents causing methemoglobinemia in a patient population seen at a medical center. Our data also are consistent with recent epidemiology trends showing increase in suicide attempts using sodium nitrite.

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PURPOSE: There is an unmet need for effective renal sparing treatments for upper tract urothelial carcinoma (UTUC). Gemcitabine/Docetaxel (Gem/Doce) has shown favorable efficacy in nonmuscle invasive bladder cancer. We report the outcomes of patients treated with endoluminal Gem/Doce for noninvasive high-grade UTUC. METHODS: A retrospective review of patients treated with Gem/Doce for clinically noninvasive high-grade UTUC with no radiographic or endoscopically visible disease, either at diagnosis or following ablation, was performed. Treatment was instilled via nephrostomy or retrograde ureteral catheter. Induction instillations were performed weekly for 6 weeks, followed by 6 monthly instillations if disease-free. Recurrence was defined as biopsy-proven disease or high-grade (HG) cytology. Progression was defined by development of muscle invasion, metastases, or death due to cancer. Survival was assessed with the Kaplan-Meier method. RESULTS: The final cohort included 31 patients with 41 upper tract units, 51% of which would have been dialysis dependent with nephroureterectomy. Median (IQR) age was 74 years (68-81). Median follow-up was 29 months (IQR 20-58). Prior to treatment, 37 (90%) units presented with a localizing HG cytology (presumed occult CIS), and 4 (9.8%) with HG biopsy-proven disease. Sixteen (52%) patients reported any side effects; 5 were Grade 3 and 1 was Grade 5. Recurrence-free survival was 76%, 54%, and 40% at 1, 2, and 3 years, respectively. Five patients died from urothelial carcinoma. The 3-year progression-free and overall survival were 75% and 75%, respectively. CONCLUSIONS: Gem/Doce demonstrates promising safety and efficacy as a renal-sparing treatment option for high-grade UTUC in appropriately selected patients.

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BACKGROUND: Malignant peripheral nerve sheath tumor (MPNST) is an exceedingly rare and aggressive tumor, with limited literature on its management. Herein, we present our series of surgically managed craniospinal MPNSTs, analyze their outcomes, and review the literature. METHODS: We retrospectively reviewed surgically managed primary craniospinal MPNSTs treated at our institution between January 2005 and May 2023. Patient demographics, tumor features, and treatment outcomes were assessed. Neurological function was quantified using the Frankel grade and Karnofsky performance scores. Descriptive statistics, rank-sum tests, and Kaplan-Meier survival analyses were performed. RESULTS: Eight patients satisfied the inclusion criteria (4 male, 4 female). The median age at presentation was 38 years (range 15-67). Most tumors were localized to the spine (75%), and 3 patients had neurofibromatosis type 1. The most common presenting symptoms were paresthesia (50%) and visual changes (13%). The median tumor size was 3 cm, and most tumors were oval-shaped (50%) with well-defined borders (75%). Six tumors were high grade (75%), and gross total resection was achieved in 5 patients, with subtotal resection in the remaining 3 patients. Postoperative radiotherapy and chemotherapy were performed in 6 (75%) and 4 (50%) cases, respectively. Local recurrence occurred in 5 (63%) cases, and distant metastases occurred in 2 (25%). The median overall survival was 26.7 months. Five (63%) patients died due to recurrence. CONCLUSIONS: Primary craniospinal MPNSTs are rare and have an aggressive clinical course. Early diagnosis and treatment are essential for managing these tumors. In this single-center study with a small cohort, maximal resection, low-grade pathology, young age (< 30), and adjuvant radiotherapy were associated with improved survival.

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BACKGROUND: Malignant triton tumors (MTTs) are a rare and aggressive type of malignant peripheral nerve sheath tumor identified histologically by focal rhabdomyoblastic differentiation. OBSERVATIONS: A 37-year-old female with a prior history of Hodgkin lymphoma presented with acute-onset confusion, cognitive deficits, and weakness. Brain magnetic resonance imaging revealed a hemorrhagic intracranial mass later confirmed to be a malignant triton tumor. The patient underwent two resections and several courses of chemoradiation for multiple tumor recurrences and metastases. Unfortunately, despite extensive treatment, she died 2 years after initial presentation from complications of this tumor. Her overall survival (OS) of 26.7 months was double that reported in historical cohorts (OS ∼13 mos). LESSONS: The diagnosis and treatment of central nervous system MTTs are difficult and require a multidisciplinary team of neurosurgeons, radiologists, and oncologists. Histopathological analysis is required for confirmation of diagnosis. Gross-total resection of tumor and adjuvant radiation therapy have been shown to give patients the highest rates of survival and improved outcomes. Further studies and clinical trials are warranted to investigate the efficacy of chemotherapeutic agents like temozolomide, bevacizumab, and abemaciclib.