G-278 Unmasking an Atypical Presentation of Primary PLA

Periventricular haemorrhagic infarction (PVHI) is a complication of preterm birth associated with cardiorespiratory instability. To date, the role of thrombophilia as a possible additional risk factor in infants with atypical timing and presentation of PVHI has not been investigated. This was a retrospective cohort study of preterm infants who developed PVHI with an atypical timing and presentation either of antenatal onset or late in the postnatal course in the absence of a preceding sudden deterioration of their clinical condition. In infants with atypical PVHI mutation analysis of the factor V Leiden (G1691A), prothrombin (G20210A) gene, and C677T and A1298C polymorphisms in the MTHFR gene was performed, and plasma lipoprotein(a) and homocysteine levels were measured. Sixty-two preterm infants who presented with a PVHI were studied. Seventeen had an atypical presentation (seven males, 10 females; median birthweight 1170g [range 580-1990g]; median gestational age 30.6wks [range 28.7-33.7wks]). The typical PVHI group comprised 28 males and 17 females (median birthweight 1200g [range 670-2210g]; median gestational age 29.6wks [range 25.3-33.6wks]). Among the 17 infants with atypical presentation, the factor V Leiden mutation was found in seven infants (41%) as well as in the mothers of six of these seven infants; in one infant this was concomitant with a prothrombin gene mutation. A polymorphism in the MTHFR gene was also present in these infants. In two infants with an atypical presentation who were tested for this, a mutation in the COL4A1 gene was found (reported previously). All but two of the infants with an atypical presentation developed spastic unilateral cerebral palsy. An atypical presentation of PVHI in preterm infants tends to occur more often in the presence of thrombophilia. Testing of thrombophilia, especially factor V Leiden and prothrombin gene mutation, is recommended in these infants.

Introduction: Rapid prehospital identification of patients with ST-elevation myocardial infarction (STEMI) is a critical step to reduce time to treatment. Broad screening with field 12-lead ECGs can lead to a high rate of false positive STEMI activations due to low prevalence. One strategy to reduce false positive STEMI interpretations is to limit acquisition of 12-lead ECGs to patients who have symptoms strongly suggestive of STEMI, but this may delay care in patients who present atypically and lead to disparities in populations with more atypical presentations. We sought to assess patient factors associated with atypical STEMI presentation. Methods: We retrospectively analyzed consecutive adult patients for whom Los Angeles Fire Department paramedics obtained a field 12-lead ECG from July 2011 through June 2012. The regional STEMI receiving center registry was used to identify patients with STEMI. Patients were designated as having typical symptoms if paramedics documented provider impressions of chest pain/discomfort, cardiac arrest, or cardiac symptoms, otherwise they were designated as having atypical symptoms. We utilized logistic regression to determine patient factors (age, sex, race) associated with atypical STEMI presentation. Results: Of the 586 patients who had STEMI, 70% were male, 43% White, 16% Black, 20% Hispanic, 5% Asian and 16% were other or unspecified race. Twenty percent of STEMI patients (n = 117) had atypical symptoms. Women who had STEMI were older than men (74 years [IQR 62–83] vs. 60 years [IQR 53–70], p < 0.001). Univariate predictors of atypical symptoms were older age and female sex (p < 0.0001), while in multivariable analysis older age [odd ratio (OR) 1.05 per year, [95%CI 1.04–1.07, p < 0.0001] and black race (OR vs White 2.18, [95%CI 1.20–3.97], p = 0.011) were associated with atypical presentation. Conclusion: Limiting prehospital acquisition of 12-lead ECGs to patients with typical STEMI symptoms would result in one in five patients with STEMI having delayed recognition, disproportionally impacting patients of older age, women, and Black patients. Age, not sex, may be a better predictor of atypical STEMI presentation.

BackgroundAtypical symptom presentations of Acute Coronary Syndrome (ACS) are common in older adults and may contribute to diagnostic delays or missed recognition in emergency departments (EDs). National-level data examining this relationship remains limited.ObjectiveTo evaluate whether atypical chest pain presentations are associated with reduced likelihood of ACS diagnosis among U.S. adults aged 65 years and older during ED visits.MethodsWe conducted a retrospective cross-sectional study using data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2014 to 2020. ED visits by adults aged ≥65 years were analyzed. Atypical presentations were defined using Reason for Visit (RFV) codes for symptoms such as weakness, dyspnea, dizziness, nausea, syncope, and abdominal pain. The primary outcome was an ED diagnosis of ACS based on ICD-9-CM codes. Multivariable logistic regression was used to assess associations.ResultsAmong 2,470 eligible ED visits, only 15 (0.6%) were diagnosed with ACS. Of those, 7 (46.7%) presented with atypical symptoms. Atypical presentation was not significantly associated with ACS diagnosis (OR: 0.90; 95% CI: 0.32-2.49; p = 0.83). No significant associations were found with age, sex, race/ethnicity, or ED disposition. The variable "admitted to hospital from ED" was excluded due to collinearity.ConclusionNearly half of older adults diagnosed with ACS presented atypically, yet atypical presentation was not significantly associated with missed ACS diagnosis in the ED. Given the limitations of administrative data and low ACS event rates, future research using richer clinical datasets and follow-up outcomes is needed to better understand diagnostic gaps in this high-risk population.

Atypical presentation and outcome of cervicogenic headache in patients with cervical degenerative disease: A single-center experience

There is currently little information about the presentation and clinical course of the 2009 pandemic influenza A (H1N1) virus infection in chronic kidney disease (CKD) patients on hemodialysis. CKD patients are at a high risk of H1N1 infection associated complications during this pandemic. H1N1 influenza is an important differential diagnosis in CKD patients on dialysis who are short of breath or febrile. We report an atypical clinical presentation of H1N1 influenza in a CKD patient. Uremia-induced immune dysfunction might lead to this atypical presentation. Hemodialysis patients are positioned close to each other during their dialysis treatment. Delayed diagnosis due to atypical clinical presentation of H1N1 might increase their exposure to transmission of respiratory infection. Physicians should be aware of this atypical clinical presentation of H1N1 influenza in CKD patients, especially during the flu season, for early diagnosis and prompt antiviral treatment. Delayed diagnosis due to atypical clinical presentation of H1N1 might increase their exposure to transmission of respiratory infection. Physicians should be aware of this atypical clinical presentation of H1N1 influenza in CKD patients, especially during the flu season, for early diagnosis and prompt antiviral treatment.

Association between comorbidities and absence of chest pain in acute coronary syndrome with in-hospital outcome

Background: Abdominal aortic aneurysm (AAA) is a potentially fatal vascular condition that frequently presents with atypical features, creating diagnostic challenges particularly in primary and out-of-hours care settings. When ruptured, AAA carries a mortality rate approaching 80–90%, and delayed diagnosis significantly worsens outcomes. Objective: This narrative literature review examines the evidence on atypical AAA presentations, misdiagnosis rates, the role of screening and diagnostic tools, and the implications for primary care clinical governance and quality improvement. Methods: A structured search of PubMed, Cochrane Library, Scopus, and Web of Science was conducted covering literature published between March 2022 and December 2025. Search terms included 'abdominal aortic aneurysm,' 'primary care,' 'misdiagnosis,' 'rupture,' 'atypical presentation,' 'point-of-care ultrasound,' 'out-of-hours,' and 'screening.' Peer-reviewed studies, systematic reviews, clinical guidelines, and meta-analyses were included. Key Findings: Up to 39% of ruptured AAAs are initially misdiagnosed, with common mimics including renal colic, musculoskeletal pain, and urinary tract infection. Only 25–50% of patients with rAAA present with the classic triad of abdominal pain, hypotension, and pulsatile mass. Women, elderly patients, and those presenting to non-specialist settings are at particular risk of delayed diagnosis. Point-of-care ultrasound (POCUS) demonstrates sensitivity exceeding 98% and specificity of 99.84% for AAA diagnosis. Current NHS screening remains restricted to men aged 65, leaving women and younger high-risk individuals undetected. Conclusion: Improved diagnostic vigilance, expanded POCUS availability, enhanced telephone triage protocols, and inclusive screening policies are urgently needed in primary and out-of-hours care. Quality improvement programmes targeting AAA recognition should be implemented across urgent primary care settings.

Background Hepatitis A is the most common cause of acute viral hepatitis, with a typical simple, self-limiting course. But it is not free from complications. Atypical presentations, such as in the form of prolonged cholestasis, ascites, pleural effusion, relapsing hepatitis, or fulminant hepatic failure, pose challenges to disease management. Knowledge about varying presentations and identification of factors associated with atypical presentations will help to early diagnosis of atypical courses of disease.&#x0D; Objective To describe various atypical clinical presentations, biochemical findings of hepatitis A infection, and possible related factors.&#x0D; Methods Ninety-five children aged 1 to 18 years, diagnosed with hepatitis A infection, and admitted to the Department of Pediatric Gastroenterology &amp; Nutrition, BSMMU, Dhaka, Bangladesh from January 2015 to May 2018 were studied retrospectively.&#x0D; Results Atypical presentations were manifested in 19 (20%) out of 95 children with hepatitis A virus (HAV) infection. The mean age of atypical patients [6.32 (SD 3.45) years] was significantly lower than that of typical patients [8.22 (SD 3.58) years] (P=0.0041). The most common atypical manifestation was ascites (11/19), followed by hepatic encephalopathy (9/19), acute liver failure (719), thrombocytopenia (2/19), pleural effusion (2/19), and cholestasis (1; 1.1%). Children with atypical features had significantly higher international normalized ratio (INR) and serum bilirubin, as well as lower hemoglobin level than the typical group. Children of atypical group had significantly higher number of organomegaly and coagulopathy.&#x0D; Conclusion Ascites, hepatic encephalopathy, acute liver failure, thrombocytopenia, pleural effusion, and prolonged cholestasis were common forms of atypical presentation. Younger age, organomegaly, higher bilirubin level, prolonged PT, and decreased hemoglobin level could be predictive of an atypical presentation of HAV in children.

BackgroundLittle is known about how atypical disease presentations lead to diagnostic errors. Better definitions of atypical presentations may improve our understanding. We aimed to describe how atypical presentations were defined in studies of diagnostic errors in internal medicine.MethodsWe included papers that described the association between atypical presentations in adult patients and diagnostic errors in internal medicine, indexed from database inception to July 31, 2025. We excluded case reports and conference abstracts. The data were extracted through MEDLINE, Web of Science, CINAHL, Embase, Cochrane Library, Google Scholar, and MedRxiv searches.ResultsWe included 56 papers in this review. Thirty studies included a definition of atypical presentation, but there was a considerable heterogeneity among the definitions. Using basic qualitative content analysis, we developed a new approach (Primary, Suggestive, Uncommon, and Chameleon features—the PSUC approach) to describe clinical presentations and identified four patterns at high risk of diagnostic errors. Pattern 1 lacks Primary disease features (i.e., features always written in textbooks) but has Suggestive features (i.e., stimulating consideration of specific disease); Pattern 2 lacks Primary features but Suggestive and Uncommon features (i.e., uncommon but known features in specific disease) are present. Pattern 3 lacks Primary and Suggestive features but has Uncommon features and Pattern 4 is similar to 3 but with Chameleon features (i.e., primary features for other diseases).DiscussionAtypical presentations in studies of diagnostic errors in internal medicine currently have high heterogeneity. A new approach to classify atypical presentations may be useful and warrants investigation in future research.Trial RegistrationOpen Science Framework www.osf.io/27d5m.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-025-09901-z.

BackgroundFever and cough are frequently reported in COVID-19 infections, although little is known about the subgroup of symptomatic patients who do not manifest these classic symptoms. We aimed to compare clinical manifestations and outcomes for hospitalized COVID-19 patients with typical vs. atypical presentations and identify risk factors for atypical COVID-19 presentations.MethodsWe conducted a retrospective cohort of all patients hospitalized with laboratory-confirmed COVID-19 infections during 3/13- 5/13/2020 at UW Health, a network of 3 acute-care hospitals in Midwest. We defined atypical cases as patients hospitalized for COVID-19 related reasons presenting without fever and cough and compared them in univariate analysis with patients manifesting both symptoms (controls). We identified independent risk factors for atypical COVID-19 presentations by logistic regression.ResultsAmong the 163 patients hospitalized during the 60-day study frame, 39 (24%) had atypical presentations. Table 1 shows demographic, clinical manifestations, and outcomes of atypical vs. typical cases. On univariate analysis, atypical cases were more likely to be older, reside in a long-term-care facility (LTCF), have underlying diabetes mellitus, stroke, cardiac disease, and deny myalgias or dyspnea, despite having no significant difference in the prevalence of hypoxia or radiological lung infiltrates. Atypical cases also had a significantly higher Beta-Natriuretic-Peptide and lower C-Reactive-Protein, although other inflammatory markers were not significantly different. They were less likely to be admitted to the ICU, and more likely to die within 30 days, as older patients with respiratory failure and multiple comorbidities opted for comfort measures and less aggressive care. On multivariate analysis, LTCF residence was the only independent predictor for atypical status (Table 2).ConclusionLTCF residents are more likely to experience COVID-19 respiratory illness (hypoxia, pneumonia) without classic symptoms (fever, cough, myalgias, dyspnea). Given the excessive pandemic burden in the LTCF setting, timely recognition and diagnosis of these atypical, more subtle presentations is critical.DisclosuresAll Authors: No reported disclosures

A minority of initial multiple sclerosis (MS) presentations clinically or radiologically resemble other central nervous system (CNS) pathologies, acute disseminated encephalomyelitis (ADEM) or tumefactive demyelination (atypical demyelination presentations). With the aim of better defining the long-term outcomes of this group we have performed a retrospective cohort comparison of atypical demyelination versus ‘typical’ MS presentations. Twenty-seven cases with atypical presentations (both first and subsequent demyelinating events) were identified and compared with typical MS cases. Disease features analysed included relapse rates, disability severity, whole brain and lesion volumes, lesion number and distribution. Atypical cases represented 3.9% of all MS cases. There was considerable overlap in the magnetic resonance imaging (MRI) features of ADEM-like and tumefactive demyelination cases. ADEM-like cases tended to be younger but not significantly so. Atypical cases showed a trend towards higher peak expanded disability severity score (EDSS) score at the time of their atypical presentation. Motor, cranial nerve, cerebellar, cerebral and multifocal presentations were all more common in atypical cases, and less likely to present with optic neuritis. Cerebrospinal fluid (CSF) white cell counts were higher in atypical cases (p = 0.002). One atypical case was associated with peripheral blood myelin oligodendrocyte glycoprotein (MOG) antibodies, but subsequent clinical and radiological course was in keeping with MS. There was no difference in long-term clinical outcomes including annualised relapse rates (ARR), brain volume, lesion numbers or lesion distributions. Atypical demyelination cases were more likely to receive high potency disease modifying therapy early in the course of their illness. Despite the severity of initial illness, our cohort analysis suggests that atypical demyelination presentations do not confer a higher risk of long-term adverse outcomes.

Background: Budd-Chiari syndrome (BCS) is an uncommon liver disorder characterized by the obstruction of the hepatic venous outflow tract. It is characterized by an obstruction in either the hepatic veins or the inferior vena cava. We share a case study of a female patient who initially exhibited mild symptoms, like weakness, fatigue, with a history of menorrhagia, without any overt signs of chronic liver disease. Subsequent evaluation revealed that she was actually suffering from Chronic Budd-Chiari syndrome. This condition typically presents with a classical triad of symptoms: abdominal pain, hepatomegaly, and ascites. This case highlights the diagnostic challenge posed by such disorders and the need for a detailed evaluation in a case of unexplained pancytopenia. However, atypical presentations can complicate diagnosis and management. This case report highlights an uncommon presentation of BCS, detailing its clinical course, diagnostic challenges, and management strategies. Case Report: A 24-year-old female presented with generalized weakness, fatigue, and menorrhagia. She had a history of blood transfusion a few years prior. Physical examination revealed pallor and hepatosplenomegaly, without signs of heart failure or liver disease. Laboratory workup indicated severe anemia with pancytopenia, consistent with iron deficiency anemia. Despite treatment, persistent thrombocytopenia prompted further investigation. Abdominal ultrasound confirmed hepatosplenomegaly, and a triple-phase CT scan suggested Budd-Chiari syndrome. Digital Subtraction Angiography (DSA) revealed a complete blockage of the suprahepatic inferior vena cava (IVC). Balloon venoplasty and stenting were performed to improve blood flow and reduce collateral circulation. Result: Post-procedure, the patient showed marked clinical improvement, with a decrease in hepatosplenomegaly and resolution of anemia. However, thrombocytopenia persisted, necessitating ongoing monitoring. This case underscores the importance of considering atypical presentations in the diagnosis of Budd-Chiari syndrome and highlights the efficacy of advanced interventional radiology techniques in its management. Conclusion: Budd-Chiari Syndrome can present with atypical symptoms, complicating its diagnosis. Early recognition and intervention are crucial for improving patient outcomes. Advanced imaging and interventional radiology techniques play a pivotal role in managing BCS, providing symptomatic relief and improving prognosis. Recommendations: Clinicians should maintain a high index of suspicion for BCS in patients with unexplained hepatic abnormalities and pancytopenia. A multidisciplinary approach, involving hepatologists, radiologists, and hematologists, is essential for optimal management. Regular follow-up and monitoring are recommended to manage potential complications and ensure sustained patient improvement. Keywords: Budd-Chiari Syndrome, Atypical Presentation, Thrombocytopenia, Interventional Radiology, Hepatic Vein Obstruction.

This study aimed to assess the prevalence of atypical presentations and their association with diagnostic errors in various diseases. This retrospective observational study was conducted using cohort data between January 1 and December 31, 2019. Consecutive outpatients consulted by physicians from the Department of Diagnostic and Generalist Medicine at a university hospital in Japan were included. Patients for whom the final diagnosis was not confirmed were excluded. Primary outcomes were the prevalence of atypical presentations, and the prevalence of diagnostic errors in groups with typical and atypical presentations. Diagnostic errors and atypical presentations were assessed using the Revised Safer Dx Instrument. We performed primary analyses using a criterion; the average score of less than five to item 12 of two independent reviewers was an atypical presentation (liberal criterion). We also performed additional analyses using another criterion; the average score of three or less to item 12 was an atypical presentation (conservative criterion). A total of 930 patients were included out of a total of 2022 eligible. The prevalence of atypical presentation was 21.7 and 6.7 % when using liberal and conservative criteria for atypical presentation, respectively. Diagnostic errors (2.8 %) were most commonly observed in the cases with slight to moderate atypical presentation. Atypical presentation was associated with diagnostic errors with the liberal criterion for atypical presentation; however, this diminished with the conservative criterion. An atypical presentation was observed in up to 20 % of outpatients with a confirmed diagnosis, and slight to moderate atypical presentation may be the highest risk population for diagnostic errors.

Organizing pneumonia is an interstitial lung disease that affects the distal bronchiole, respiratory bronchiole, alveolar ducts, and walls. To diagnose cryptogenic organising pneumonia, other aetiologies, such as inflammatory infections, connective tissue disease, drug responses, pulmonary infarction, and organ transplantation need to be ruled out. Radiological and histological progress in this disease will help to understand the disease in a better way. Early diagnosis of organizing pneumonia is important because of a good prognosis if it is treated earlier. But atypical clinical and radiological presentation will lead to difficulty in diagnosis and delay in treatment. Here we report two atypical presentations of organizing pneumonia cases to highlight the importance of upfront aggressive multimodality diagnostic approaches to rule out rare causes of cavitating lesions.

Ataxia-telangiectasia (AT) is a rare autosomal recessive neurodegenerative multisystem disorder. A minority of AT patients can present late-onset atypical presentations due to unknown mechanisms. The demographic, clinical, immunological and genetic data were collected by direct interview and examining the Iranian AT patients with late-onset manifestations. We also conducted a systematic literature review for reported atypical AT patients. We identified three Iranian AT patients (3/249, 1.2% of total registry) with later age at ataxia onset and slower neurologic progression despite elevated alpha-fetoprotein levels, history of respiratory infections, and immunological features of the syndrome. Of note, all patients developed autoimmunity in which a decrease of naïve T cells and regulatory T cells were observed. The literature searches also summarized data from 73 variant AT patients with atypical presentation indicating biallelic mild mutations mainly lead to an atypical phenotype with an increased risk of cancer. Variant AT patients present with milder phenotype or atypical form of classical symptoms causing under- or mis- diagnosis. Although missense mutations are more frequent, an atypical presentation can be associated with deleterious mutations due to unknown modifying factors.