ABSTRACT
PURPOSE OF REVIEW: Choanal atresia (CA) is a congenital nasal airway anomaly that, when present bilaterally, requires urgent surgical intervention. Surgical technique has evolved since its inception with most practices now favoring an endoscopic repair. Restenosis requiring revision surgery is a frequent complication, occurring in as many as 50% of cases. This review aims to highlight the most common surgical approaches, techniques used to prevent restenosis, and newer adjuncts to surgery that may improve outcomes. RECENT FINDINGS: Bioabsorbable, steroid-eluting stents were first developed for the adult chronic rhinosinusitis population but have been adapted for use in choanal atresia since 2017. The existing literature consists of multiple case series and one case-control study comparing these stents to traditional stents. To date, there have been no reports of restenosis or stent-related complications with these newer products. SUMMARY: Choanal atresia remains a difficult surgical pathology for which sustainable surgical results can be challenging. There is reason for optimism in bioabsorbable, steroid-eluting stents as an adjunct to CA repair if future studies expound upon their safety and efficacy.
ABSTRACT
Extramedullary hematopoiesis occurs in children with hemoglobinopathy and chronic anemia. The liver and spleen are often affected first, but other foci can develop to support erythrocyte demand. We report a case of a nine-year-old with beta thalassemia and temporal bone extramedullary hematopoiesis causing ossicular fixation and bilateral conductive hearing loss. There is only one case in the literature describing this phenomenon in pediatric patients, and this is the first case report of bilateral hearing loss from this physiologic phenomenon. Otolaryngologists should consider this etiology in patients with chronic anemia and conductive hearing loss in the absence of otitis media.
Subject(s)
Hearing Loss, Conductive/etiology , Hematopoiesis, Extramedullary/physiology , Temporal Bone/pathology , beta-Thalassemia/complications , Audiometry , Child , Humans , Male , Otoscopes , Tomography, X-Ray ComputedABSTRACT
IMPORTANCE: The use of 3-dimensional (3D) endoscopy has been described in the pediatric airway and has been shown to improve visualization of complex airway anatomy. Laryngomalacia is one of the most common airway disorders evaluated in pediatric otolaryngology offices. Whether 3D visualization is superior to standard endoscopy as a means for assessment and surgical management of complex airway anatomy is unclear. OBJECTIVE: To describe a pilot case series using 3D endoscopy to facilitate supraglottoplasty and to assess surgical outcomes. DESIGN, SETTING, AND PARTICIPANTS: A prospective case series was conducted of 11 children undergoing supraglottoplasty from July 1, 2010, to June 31, 2014, at a tertiary care pediatric hospital. Infants and children with symptomatic laryngomalacia were eligible for the study. Follow-up was completed on December 31, 2014, and data were assessed from February 1 to 15, 2015. INTERVENTIONS: Supraglottoplasty performed using 3D endoscopy. MAIN OUTCOMES AND MEASURES: The outcome data collected included length of hospital stay and frequency of complications (ie, aspiration, granuloma formation, supraglottic narrowing, revision surgery, tracheostomy, and gastrostomy). RESULTS: Eleven children were treated for laryngomalacia with supraglottoplasty (6 boys and 5 girls; mean [SD] age, 29 [85] months). Four of these children (36%) also had grade I subglottic stenosis. The 3D endoscope was judged by all participating senior surgeons to improve visualization of the supraglottic anatomy and to permit more precise tissue removal. No complications occurred after the surgery. Hospital stay was found to be an unreliable indicator owing to multiple comorbidities in many children. Worsening of aspiration occurred in 1 child (9%) who subsequently required gastrostomy tube placement. This child demonstrated progressive neurologic impairment and had severe hypotonia and developmental delay. Another child with subglottic stenosis and subglottic cysts required a tracheostomy owing to severe rhinovirus tracheitis. The remaining 9 children (82%) had good outcomes, with a mean follow-up of 14.7 (range, 12-24) months. CONCLUSIONS AND RELEVANCE: The anatomy of the supraglottis in laryngomalacia is better visualized using 3D techniques. Use of 3D endoscopy may allow for more precise tissue removal. The outcomes and complication rates are similar to those of standard 2D techniques. This study provides a platform to begin comparative analysis between 3D and standard 2D techniques.
Subject(s)
Endoscopy/methods , Epiglottis/pathology , Imaging, Three-Dimensional/methods , Laryngomalacia/diagnosis , Child, Preschool , Epiglottis/surgery , Female , Follow-Up Studies , Humans , Laryngomalacia/complications , Laryngomalacia/surgery , Laryngoplasty/methods , Laryngostenosis/diagnosis , Laryngostenosis/etiology , Laryngostenosis/surgery , Male , Prospective Studies , Reproducibility of Results , Treatment OutcomeABSTRACT
Peritonsillar infections are one of the most common deep neck space infections, particularly in adolescents. Inaccurate diagnosis can lead to delay in management and potentially life-threatening complications. Contrast-enhanced computed tomography (CT) scan of the neck traditionally has been used to diagnose suspected peritonsillar abscess. With growing concern over radiation exposure, there has been increasing utilization of ultrasound (US) using intraoral and transcutaneous approaches. We chose the transcutaneous US technique due to its ease of performance in children. The purpose of this article is twofold: a) to describe our technique of performing transcutaneous US of the tonsil showing sonographic appearance of normal tonsil, highlighting pertinent anatomy and unique considerations for this modality in children, and b) to illustrate the sonographic findings in the spectrum of pediatric peritonsillar infections, which includes uncomplicated tonsillitis, peritonsillar cellulitis, small intratonsillar abscess and frank peritonsillar abscess. Parapharyngeal abscess can sometimes be detected.
Subject(s)
Peritonsillar Abscess/diagnostic imaging , Ultrasonography/methods , Child , Contrast Media , Diagnosis, Differential , HumansABSTRACT
OBJECTIVES/HYPOTHESIS: Pediatric peritonsillar abscess (PTA) is a common infection, particularly in the adolescent population. Physical examination alone is not always sufficient to diagnose this pathology, and thus, computed tomography is often utilized as a diagnostic adjunct. With growing concern over radiation exposure in the pediatric population, we conducted a prospective study to investigate the use of ultrasonography in the detection of pediatric PTA. STUDY DESIGN: Prospective single arm cohort study. METHODS: Pediatric patients examined in consultation for concern for PTA were prospectively enrolled in the study. Patients were managed based on clinical symptoms and presentation. Transcervical ultrasonography of the peritonsillar region was performed on all patients. Clinical outcomes were reviewed retrospectively and compared to ultrasound findings. RESULTS: Forty-three patients (age range, 2-20 years) were enrolled in the study. The sensitivity and specificity of transcervical ultrasound when compared to clinical outcomes were 100% and 76.5%, respectively. The positive and negative predictive values were 52.9% and 100%, respectively. Fisher exact test showed a statistically significant association (P < .01) between negative ultrasonography and successful medical management, and multivariate regression analysis showed a strong correlation between ultrasound findings and presence/absence of purulence during surgical intervention (P = .01). CONCLUSIONS: Transcervical ultrasonography is a useful tool in diagnosing pediatric PTA. This imaging modality not only avoids undue radiation exposure, but it also proves to be an excellent tool at identifying patients who will not need surgical intervention. To our knowledge, this is the first study to explore this technique for the diagnosis of pediatric PTA. LEVEL OF EVIDENCE: 2b.
Subject(s)
Peritonsillar Abscess/diagnostic imaging , Adolescent , Child , Child, Preschool , Cohort Studies , Female , Humans , Male , Pediatrics , Peritonsillar Abscess/diagnosis , Predictive Value of Tests , Prospective Studies , Retrospective Studies , Sensitivity and Specificity , Ultrasonography , Young AdultABSTRACT
OBJECTIVE: Reactive oxygen species (ROS) can potentiate cellular injury and inflammation. This study aimed to (1) assess the presence of reactive oxygen species in the sinus tissue of patients with chronic rhinosinusitis (CRS) and (2) assess the impact of secondhand smoke (SHS) exposure on reactive oxygen species (ROS) production. STUDY DESIGN: Retrospective cohort study. SETTING: Academic medical center. SUBJECTS AND METHODS: Sinus tissue samples from patients undergoing sinus surgery were analyzed using diaminobenzidine (DAB) staining to assess for ROS. Stained specimens were photographed at random by a blinded photographer and then quantified by 3 blinded graders. The patient's SHS exposure was determined by hair nicotine levels. RESULTS: were compared between non-smoke exposed cohorts and those exposed to secondhand smoke and by diagnosis. RESULTS: Sixty-nine adults undergoing sinus surgery were included in the study. For the non-SHS-exposed cohorts, chronic rhinosinusitis with nasal polyps (CRSwNP) had the highest number of DAB+ cells/high-powered field (hpf) followed by chronic rhinosinusitis without nasal polyps (CRSsNP) and controls. When comparing the control patients to their SHS-exposed counterparts, SHS exposure yielded statistically significantly higher levels of DAB-positive cells/hpf. SHS exposure did not affect DAB staining in CRSsNP or CRSwNP patients. CONCLUSION: ROS are differentially expressed in various subtypes of CRS. SHS exposure increases ROS in sinus tissue of control patients, but the clinical significance of this is unclear.
Subject(s)
Reactive Oxygen Species/metabolism , Rhinitis/metabolism , Sinusitis/metabolism , Tobacco Smoke Pollution , Adult , Chronic Disease , Female , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
OBJECTIVES/HYPOTHESIS: To retrospectively analyze the postoperative management and care needs of patients undergoing spontaneous ventilation supraglottoplasty (SVS). STUDY DESIGN: Retrospective chart review. METHODS: Charts of children undergoing (SVS) for severe laryngomalacia from 2007 to 2011 at a single institution were reviewed. Intraoperative and postoperative management data were collected to review the airway management, postoperative care needs, and potential complications associated with this surgery. RESULTS: A total of 65 patients were included in the study. Only three patients (4.5%) required more than an overnight stay in the hospital, and no patients left the operating room intubated. One patient required temporary intensive care unit observation, and the majority (78.1%) demonstrated adequate oral intake within 4 hours of surgery. Comorbidities did not portend a longer hospital stay or slower return to oral intake. CONCLUSIONS: SVS with cold-steel instruments is a safe and effective surgical intervention with low complication rates. This study suggests that postoperative intubation or intensive care unit monitoring may not be necessary when using these techniques.
Subject(s)
Laryngomalacia/surgery , Otorhinolaryngologic Surgical Procedures/methods , Plastic Surgery Procedures/adverse effects , Postoperative Care/methods , Female , Follow-Up Studies , Glottis/surgery , Humans , Infant , Laryngomalacia/diagnosis , Male , Retrospective Studies , Severity of Illness Index , Treatment OutcomeABSTRACT
OBJECTIVE: To determine whether the human papillomavirus (HPV) status of head and neck squamous cell carcinomas (HNSCCs) can be reliably predicted based on sociodemographic and disease characteristics alone. DESIGN A retrospective medical chart review of clinical and pathologic features. SETTING: Tertiary academic medical center. PATIENTS: We studied patients treated for HNSCC who were tested for markers of HPV or had tissue available for testing between 2006 and 2010. MAIN OUTCOME MEASURES: Four otolaryngology-head and neck surgery trainees were given the database of patient clinical and pathologic features and asked to predict the HPV status for each patient. The trainees' responses were scored for accuracy, positive and negative predictive value, and interrater agreement. Multiple linear regression analyses were performed to determine predictors of HPV positivity. RESULTS: A total of 174 patients meeting inclusion criteria were identified, 95 of whom were determined to have HPV-positive tumor tissue. Residents were able to accurately predict HPV status in 110 to 125 patients (63%-72%), with positive predictive values of 76% to 84% and negative predictive values of 61% to 69%. The only variables significantly related to HPV status were male sex (P = .01) and oropharyngeal subsite (P = .02). Only 4 patients had a "typical" HPV-positive profile. CONCLUSIONS: Knowledge of cancer stage, primary site, basaloid features, tumor differentiation, and presence of cystic neck disease and patient age, race, and smoking status did not allow accurate predictions of HPV status in many patients. Clinical testing of tumor tissue remains essential for a diagnosis of HPV-positive disease.
Subject(s)
Carcinoma, Squamous Cell/virology , Head and Neck Neoplasms/virology , Papillomaviridae/isolation & purification , Carcinoma, Squamous Cell/surgery , Female , Head and Neck Neoplasms/surgery , Humans , Immunohistochemistry , In Situ Hybridization , Male , Middle Aged , Predictive Value of Tests , Retrospective Studies , Reverse Transcriptase Polymerase Chain Reaction , Risk Factors , Socioeconomic FactorsABSTRACT
A series of simple tests have been used to measure the performance of flat-bed film scanners suitable for digitisation of electron micrographs. Two of the film scanners evaluated are commercially available and one has been constructed in the laboratory paying special attention to the needs of the electron microscopist. The tests may be useful for others.
Subject(s)
Image Processing, Computer-Assisted/instrumentation , Microscopy, Electron/instrumentationSubject(s)
Prosthesis Failure , Silicone Gels , Testis , Humans , Male , Middle Aged , Rupture, SpontaneousABSTRACT
Intra-abdominal (as opposed to extremity or limb and limb-girdle) soft tissue sarcomas (STS) are rare and account for less than 1% of all diagnosed neoplasms. These tumours are usually associated with a poor prognosis and are often locally invasive and metastatic at the time of presentation. Retroperitoneal sarcomas with synchronous or metachronous different histological types are rare and intra-duodenal sarcomas extremely unusual. A case of a giant retroperitoneal STS weighing approximately 15 kg consisting of two histologically different types is presented. Intra-duodenal involvement with sarcoma was found intra-operatively. We discuss the management of this condition in the context of an illustrative case in our recent experience.
Subject(s)
Duodenal Neoplasms/surgery , Liposarcoma/surgery , Neoplasms, Multiple Primary/surgery , Retroperitoneal Neoplasms/surgery , Sarcoma/surgery , Adult , Duodenal Neoplasms/pathology , Humans , Liposarcoma/pathology , Male , Neoplasms, Multiple Primary/pathology , Retroperitoneal Neoplasms/pathology , Sarcoma/pathology , Treatment OutcomeABSTRACT
OBJECTIVE: To document long-term survival in patients with renal cell carcinoma (RCC) in whom the primary tumour was left in situ and treatment limited to palliative and symptomatic measures. PATIENTS AND METHODS: All patients with a diagnosis of RCC from January 1994 to January 1999 and in whom the primary tumour was left in situ were identified from hospital records (nine women and 16 men, mean age 69 years). The tumour stage was T1-T4. RESULTS: The mean survival overall was 19.3 months; patients with locally advanced disease, i.e. stage >or= T3a, had a mean survival of 16.9 months. CONCLUSIONS: There is renewed interest in the management of advanced RCC, with data supporting cytoreductive nephrectomy with systemic biological therapy. These results confirm that such patients with or without metastatic disease can survive for a considerable period with no aggressive surgical or systemic measures, and such intervention may offer no significant advantage in outcome and survival over supportive treatment alone.
Subject(s)
Carcinoma, Renal Cell/therapy , Kidney Neoplasms/therapy , Aged , Aged, 80 and over , Carcinoma, Renal Cell/mortality , Female , Humans , Kidney Neoplasms/mortality , Male , Middle Aged , Palliative Care , Survival Analysis , Treatment OutcomeABSTRACT
Gonococcal urethritis in a heterosexual male complicated by periurethral abscess and its treatment with antibiotics and surgical drainage is presented.
Subject(s)
Abscess/etiology , Abscess/therapy , Drainage/methods , Gonorrhea/complications , Urethritis/complications , Adult , Anti-Infective Agents/therapeutic use , Catheterization , Drainage/instrumentation , Humans , Male , Metronidazole/therapeutic use , Urethritis/microbiologyABSTRACT
AIM: Ten percent of soft tissue sarcomas (STS) arise in the retroperitoneal tissues. The prognosis for patients with retroperitoneal sarcoma is poor with a 5-year survival rate between 12% and 70%. Stage at presentation, high histological grade, unresectable primary tumour and incomplete resection are associated with a less favourable outcome. METHODS: Complete follow-up data were available on 22 patients who underwent surgery for retroperitoneal STS in our institution between 1990 and 2000. Patient, tumour and treatment variables were analysed including use of adjuvant therapy and survival status. RESULTS: Eighteen patients underwent surgery for primary disease, four patients were treated for recurrent disease or metastases. Ten patients presented with pain, seven with an abdominal mass, other presentation included weight loss and haematuria. Thirteen patients presented with tumours larger than 10 cm. The tumours were seven liposarcomas, six leiomyosarcomas, three malignant fibrous histiocytomas, two rhabdomyosarcomas, two malignant schwannomas and two undifferentiated sarcomas. Six primary tumours were completely excised, five patients received radiotherapy and five received chemotherapy. Local recurrence rate was 45% and recurrence-free interval for 10 patients with recurrence was 11 months. Five patients received radiotherapy and five received chemotherapy. The median survival for patients with primary tumours was 36 months, and 5-year survival was 44%. Adjuvant therapy was not associated with higher survival rates. CONCLUSION: This study re-emphasizes the poor outcome of patients with retroperitoneal STS. Adjuvant radiotherapy and chemotherapy do not appear to be any proven benefit and the single most important prognostic factor is aggressive successful en bloc resection of the primary tumour. Our resection rate and 5-year survival rates are comparable with previous reported UK series although lower than large reports from North American centres. This might partly be explained by difficulty in data collection in a retrospective analysis, but may reflect inadequate subspecialization in UK centres.
Subject(s)
Retroperitoneal Neoplasms/surgery , Soft Tissue Neoplasms/surgery , Adult , Aged , Aged, 80 and over , Female , Follow-Up Studies , Histiocytoma, Benign Fibrous/surgery , Humans , Male , Middle Aged , Neurilemmoma/surgery , Prognosis , Retroperitoneal Neoplasms/diagnostic imaging , Retroperitoneal Neoplasms/drug therapy , Retroperitoneal Neoplasms/radiotherapy , Retrospective Studies , Sarcoma/surgery , Soft Tissue Neoplasms/diagnostic imaging , Soft Tissue Neoplasms/drug therapy , Soft Tissue Neoplasms/radiotherapy , Survival Analysis , Tomography, X-Ray Computed , Treatment OutcomeABSTRACT
Many woody species can be propagated from leafy cuttings. However, following rooting, cuttings of Corylus maxima Mill. cv. Purpurea do not always survive the transition from a highly supportive rooting environment (e.g., fog) to a more natural environment where evaporative demand is higher. We found that it is not the supply of water to leaves, but stomatal dysfunction that leads to severe water deficits in the rooted cuttings. Two hours after well-rooted cuttings were transferred from the rooting environment, we were able to relate visible signs of leaf water deficit to high stomatal conductance (g(s)) and low relative water content (R). Small expanding leaves (L3) had unusually high g(s) and lower R than fully expanded leaves (L1). Although high cuticular conductances (g(c)) were occasionally observed in L3, SEM confirmed that increased total leaf conductance (g) was mainly a result of abnormally wide stomatal opening. We measured changes in the ability of stomata to control water loss during rooting by determining stomatal responsiveness to leaf water deficit in detached L1 and L3 harvested from cuttings during the first 75 days after severance from stock plants. Reduced stomatal responsiveness was observed within 7 days of severance, prior to adventitious root formation, and was more pronounced in L3 than in L1. A period of acclimatization after rooting (no leaf wetting, but a vapor pressure deficit of 0.20 kPa) reduced g(s) by 50% in L3 but not in L1, and partially restored stomatal responsiveness in L1 but not in L3. After rooting, the original leaves on the cutting retained substantial capacity for photosynthesis (e.g., in L1, 8 micromol m(-2) s(-1) at a photosynthetic photon flux density of 400 micromol m(-2) s(-1)). The implications of the results for post-rooting acclimatization procedures are discussed.
Subject(s)
Betulaceae/physiology , Plant Leaves/physiology , Trees/physiology , Photosynthesis/physiology , Water/physiologyABSTRACT
The author discussed various advanced roles for the perioperative RN; commitment and passion for the OR professional; the need for education, education, education; and how to plan your career.
Subject(s)
Career Mobility , Leadership , Nursing Care/organization & administration , Perioperative Nursing/trends , HumansABSTRACT
Heat shock proteins (hsps) occupy a central role in the regulation of intracellular homeostasis, and differential expression of individual hsps occurs in a broad range of neoplastic processes. This study was performed to test the hypothesis that the particular patterns by which individual hsps become specifically modulated in human prostate cancers are correlated with behavioral phenotype and hence may be of value in determining the most appropriate clinical management of individual patients. Monoclonal antibodies specific for each hsp protein were used to assess expression of hsp27, hsp60, and hsp70 in formalin-fixed, paraffin wax-embedded, archival tissue specimens of early prostatic adenocarcinomas (pT1-2N0M0) removed at radical prostatectomy (n = 25) and in advanced cancers (n = 95) identified at transurethral resection of prostate (TURP). These findings were compared with similar data from control prostates (n = 10) removed at primary cystectomy for urinary bladder neoplasia not involving the prostate and also at TURP for benign prostatic hyperplasia (n = 50). Western blotting of whole cell lysates derived from established human prostatic epithelial cell lines PNT2, LNCaP, DU145, and PC3 was compared with expression of hsps by the primary human tissues. This study found that early in situ neoplastic transformation of normal prostatic epithelium was consistently associated with loss of hsp27 expression and that the level of hsp27 expression by individual prostate cancers was correlated with their Gleason grade. In advanced cancers, hsp27 expression was invariably associated with poor clinical outcome (P = 0.0001). Data from cell lines supported the primary tissue findings, with elevated hsp27 expression only in aggressive malignant cell lines and androgen-insensitive cell lines. Expression of hsp60 was significantly increased in both early and advanced prostate cancer when compared with nonneoplastic prostatic epithelium (P < 0.0001), as well as in malignant prostate cancer cell lines. Expression of hsp70 was unaltered in early prostate cancers when compared with nonneoplastic prostatic epithelium but showed a diminished expression in morphologically advanced cancers (P = 0.0029). No consistent correlation was found between levels of hsp60 or hsp70 expression and phenotypic behavior of individual primary prostatic cancers. Thus, patterns of hsp expression have been confirmed to be specifically and consistently modulated in both early and advanced human prostate cancers. Whereas absence of hsp27 is a reliable objective marker of early prostatic neoplasia, reexpression of this protein by an individual invasive prostatic carcinoma invariably heralds poor clinical prognosis. Because this protein has been shown to alter the balance between proliferation and apoptosis, understanding the mechanism(s) by which individual hsps regulate intracellular homeostasis may assist in explaining some key processes that occur during evolution of human prostate cancers. We suggest that hsp27 expression provides novel diagnostic and prognostic information on individual patient survival which, if obtained at the time of primary diagnosis, would assist in determining tumor-specific management strategies. Development of techniques to therapeutically modulate hsp27 expression raises the possibility of novel targeted approaches to regulate this homeostatic mechanism, thus allowing better control over tumor cell proliferation and hence patient survival.
Subject(s)
Heat-Shock Proteins/biosynthesis , Prostatic Neoplasms/diagnosis , Prostatic Neoplasms/metabolism , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Aged , Aged, 80 and over , Antibodies, Monoclonal , Blotting, Western , Chaperonin 60/biosynthesis , Epithelium/metabolism , Epithelium/pathology , HSP27 Heat-Shock Proteins , HSP70 Heat-Shock Proteins/biosynthesis , Humans , Immunohistochemistry , Male , Middle Aged , Molecular Chaperones , Neoplasm Proteins/biosynthesis , Prostate/metabolism , Prostate/pathology , Prostatic Neoplasms/pathology , Treatment Outcome , Tumor Cells, CulturedABSTRACT
PIP: People who experience disaster are widely regarded as an undifferentiated group of victims. In the immediate crisis period, it is hard for outside professionals to differentiate between varying levels of need and still carry out their pressing disaster-related tasks. However, soon after a disaster strikes, it becomes clear that some people were hit harder than others and that disasters are not the great levelers they are sometimes thought to be. Rather, complex variations exist both within and between social groups broadly understood as middle- and working-class. The author explores the intersection of gender and social class in 2 major flood events in Scotland, Perth in 1993 and Strathclyde in 1994, and argues for a better appreciation of these factors at the conceptual and practical levels, to be incorporated into the disaster management process.^ieng
Subject(s)
Disasters , Interpersonal Relations , Social Class , Developed Countries , Economics , Environment , Europe , Scotland , Socioeconomic Factors , United KingdomABSTRACT
Acclimation to elevated CO2 was investigated in Parmelia caperata originating from the vicinity of a natural CO2 spring, where the average daytime CO2 concentration was 729 ± 39 µmol mol-1 dry air. Thalli showed no evidence of a down-regulation in photosynthetic capacity following long-term exposure to CO2 enrichment in the field; carboxylation efficiency, total Ribulose bisphosphate carboxylase/oxygenase (Rubisco) content, apparent quantum yield of CO2 assimilation, and the light-saturated rate of CO2 assimilation (measured under ambient and saturating CO2 concentrations) were similar in thalli from the naturally CO2 enriched site and an adjacent control site where the average long-term CO2 concentration was about 355 µmol mol-1. Thalli from both CO2 environments exhibited low CO2 compensation points and early saturation of CO2 uptake kinetics in response to increasing external CO2 concentrations, suggesting the presence of an active carbon-concentrating mechanism. Consistent with the lack of significant effects on photosynthetic metabolism, no changes were found in the nitrogen content of thalli following prolonged exposure to elevated CO2. Detailed intrathalline analysis revealed a decreased investment of nitrogen in Rubisco in the pyrenoid of algae located in the elongation zone of thalli originating from elevated CO2, an effect associated with a reduction in the percentage of the cell volume occupied by lipid bodies and starch grains. Although these differences did not affect the photosynthetic capacity of thalli, there was evidence of enhanced limitations to CO2 assimilation in lichens originating from the CO2-enriched site. The light-saturated rate of CO2 assimilation measured at the average growth CO2 concentration was found to be significantly lower in thalli originating from a CO2-enriched atmosphere compared with that of thalli originating and measured at ambient CO2. At lower photosynthetic photon flux densities, the light compensation point of net CO2 assimilation was significantly higher in thalli originating from elevated CO2, and this effect was associated with higher usnic acid content.