EARLY IDENTIFICATION OF PERITONSILLAR ABSCESS IN TONSILLITIS PATIENTS USING INFLAMMATORY BLOOD MARKERS

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KBB-Forum 2026 , Cilt 25 , Sayı 3

EARLY IDENTIFICATION OF PERITONSILLAR ABSCESS IN TONSILLITIS PATIENTS USING INFLAMMATORY BLOOD MARKERS

Agah YENİÇERİ; ¹, MD Ayşe Seçil KAYALI DİNÇ; ¹, Prof Çetin ŞAHUTOĞLU; ¹, MD Kardelen KAYIŞ; ¹, MD Melih ÇAYÖNÜ; ¹, Prof

¹Ankara Bilkent Şehir Hastanesi, Kulak Burun Boğaz, Ankara, Türkiye

Summary

Objective: This study aimed to evaluate the effectiveness of inflammatory markers in predicting the development of peritonsillar abscess (PTA) in patients with tonsillitis and to identify key hematological parameters associated with PTA, thereby contributing to early recognition and risk classification of severe tonsillar infections.

Methods: A retrospective analysis was conducted on 382 patients (210 with PTA, 172 with tonsillitis) between April 2019 and January 2024. Demographic, clinical, and laboratory data, including complete blood count (CBC) and C-reactive protein (CRP) levels, were analyzed. Inflammatory markers such as white blood cell (WBC), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and systemic inflammation response index (SIRI) were assessed. Statistical analyses included descriptive statistics, regression models, and receiver operating characteristic (ROC) curve analysis.

Results: Significant differences in inflammatory markers were observed between the PTA and tonsillitis groups (p < 0.05). WBC, CRP, SII, and SIRI demonstrated the highest diagnostic value with areas under the curve (AUC) of 0.833, 0.777, 0.719, and 0.763, respectively. WBC and CRP were the most accurate biomarkers for diagnosing PTA, with sensitivities of 76% and 74%, and specificities of 77% and 75%, respectively. After adjustment for gender, WBC, CRP, SII, and SIRI remained significant independent predictors of peritonsillar abscess.

Conclusion: Our findings highlight the diagnostic value of WBC and CRP in distinguishing PTA from uncomplicated tonsillitis. SII and SIRI were also identified as useful supportive markers. Integrating these inflammatory markers into clinical practice can enhance early diagnosis, improve risk stratification, and optimize patient management.

Summary

Introduction

Tonsillitis is an acute or chronic inflammation of the palatine tonsils and represents one of the most common infections of the upper respiratory tract. Group A beta-hemolytic streptococcus (Streptococcus pyogenes) is the most commonly identified bacterial pathogen in acute cases[1]. However, studies indicate that 70% to 95% of tonsillitis cases are of viral origin[2]. Clinical manifestations include sore throat, fever, odynophagia, and cervical lymphadenopathy, with disease severity varying according to the etiological agent and the host immune response[1]. Although most cases of tonsillitis resolve with appropriate medical treatment, serious complications may develop, particularly when the infection extends beyond the tonsillar tissue.

One of the most common suppurative complications of tonsillitis is peritonsillar abscess (PTA), a localized collection of pus between the tonsillar capsule and the pharyngeal muscles[3,4]. PTA is a frequent cause of emergency department visits and hospitalization in otolaryngology practice[5]. Patients with PTA typically present with more severe symptoms, including trismus, muffled (“hot potato”) voice, severe unilateral throat pain, odynophagia, and uvular deviation[6]. When combined with appropriate antibiotic therapy, needle aspiration, incision, and drainage represent effective treatment strategies for PTA[4,7]. Early recognition and prompt treatment of PTA are essential to prevent progression to more advanced complications requiring surgical intervention. If left untreated, it can progress to life-threatening complications such as parapharyngeal or retropharyngeal abscesses, airway obstruction, septicemia, and Lemierre syndrome[8].

Early differentiation between uncomplicated tonsillitis and PTA is crucial for appropriate management. Clinical examination alone has limited reliability in distinguishing peritonsillar cellulitis from PTA[3]. Although clinical examination and patient history provide valuable diagnostic clues, inflammatory markers and imaging modalities may further improve diagnostic accuracy[3,9]. In recent years, various hematological markers have been investigated and proposed as potential indicators of infection severity and disease progression[9-12].

However, the clinical presentation of PTA can often be ambiguous, and distinguishing the early stages of uncomplicated tonsillitis from PTA remains a challenge in clinical practice. The aim of this study was to evaluate the diagnostic value of inflammatory markers in differentiating PTA from tonsillitis and to identify key hematological parameters associated with PTA, thereby contributing to the early recognition and risk classification of patients with severe tonsillar infections.

Introduction

Methods

Study design
This study was designed as a retrospective case-control analysis based on medical records. This study was conducted in accordance with the principles of the Declaration of Helsinki. Ethical approval was obtained from the hospital’s ethics committee prior to the initiation of the study (Ethical approval number: TA-BED-2-25-1055).

Patients
This retrospective study included a total of 382 patients, comprising 210 individuals diagnosed with peritonsillar abscess and 172 with tonsillitis. All patients were selected from the medical records of a single tertiary care center, between April 2019 and January 2024. The study population was formed by retrospectively identifying patients who met the predefined inclusion criteria. Patients aged 18 to 55 years, without any other diagnosed infection, who had complete blood count (CBC) and C-reactive protein (CRP) tests available were included. Patients who had used antibiotics in the last 14 days, received anti-inflammatory therapy, or had oncological diseases, immune deficiency, or chronic diseases that could alter inflammatory marker levels were excluded. All patient data were anonymized to ensure confidentiality.

Data collection
Demographic and clinical data, including age, gender, and laboratory test results, were retrospectively collected from medical records. In patients with a preliminary diagnosis of PTA, contrast-enhanced computed tomography (CT) was performed to confirm the diagnosis. In this study, abscess diameter was retrospectively obtained from the corresponding CT reports. Complete blood count (CBC) and C-reactive protein (CRP) levels obtained at the time of initial diagnosis were analyzed. From the CBC, white blood cell (WBC), neutrophil (NEU), lymphocyte (LYM), monocyte (MONO), and platelet (PLT) counts, as well as the delta neutrophil index (DNI), large unstained cell count (#LUC), and large unstained cell percentage (%LUC), were recorded. Based on these laboratory parameters, the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII = neutrophil count × platelet count / lymphocyte count), and systemic inflammation response index (SIRI = neutrophil count × monocyte count / lymphocyte count) were calculated.

Statistical Analysis
Statistical analysis was performed using SPSS software (v20; IBM SPSS Statistics, Chicago, IL, USA). For descriptive statistics, categorical variables are expressed as number (n) and percentage (%), and while continuous variables are expressed as median and interquartile range (IQR) due to non-normal data distribution. The patients were divided into two groups: peritonsillar abscess and tonsillitis. The distribution of all continuous numerical variables was assessed using the One-Sample Kolmogorov-Smirnov test, which revealed that the data did not follow a normal distribution. Differences between the groups in terms of the investigated parameters were evaluated using the Mann-Whitney U test for nonparametric two-independent samples and the chi-square test. Binary logistic regression analyses adjusted for gender were performed to evaluate whether the inflammatory markers with the highest diagnostic performance in ROC analysis (WBC, CRP, SII, and SIRI) were independently associated with peritonsillar abscess. Separate regression models were constructed for each marker, and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Additionally, a receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of the investigated inflammatory markers and to evaluate the diagnostic performance and discriminative ability in tonsillitis patients. Ap-value of <0.05 was considered statistically significant.

Methods

Results

In the study, the demographic and clinical features of the patients are presented in Table 1. The median age was 30 (IQR: 13) years in patients with PTA and 32 (IQR: 13.7) years in patients with tonsillitis, with no statistically significant difference between the groups (p = 0.146).

Regarding gender distribution, there was a significant difference between the two groups. In the PTA group, 80 patients (38%) were female, and 130 patients (62%) were male. In contrast, the tonsillitis group consisted of 90 females (52.3%) and 82 males (47.7%), with a significant gender difference observed (p = 0.005). The median abscess diameter was 20 mm (IQR: 11.25) in patients with PTA.

In the comparison of inflammatory markers between PTA and tonsillitis groups, significant differences were observed in several markers. WBC, #LUC, %LUC, DNI, CRP, SIRI, SII, NLR, and MLR all showed statistically significant differences (p < 0.05), with values in the PTA group generally higher than in the tonsillitis group. However, PLR showed no significant difference between the two groups (p = 0.86) (Table 2).

Table 1: Demographic and clinical features of the patients

The ROC analysis was performed to assess the diagnostic performance of various inflammatory markers in predicting the risk of developing PTA. The results showed that WBC, CRP, SII, and SIRI had significant diagnostic value (p<0.001). WBC had an AUC of 0.833 (95% CI: 0.79–0.87), with a cut-off value of 10.9, sensitivity of 76%, and specificity of 77%. CRP demonstrated an AUC of 0.777 (95% CI: 0.73–0.825), with a cut-off value of 41.7, sensitivity of 74%, and specificity of 75%. SII showed an AUC of 0.719 (95% CI: 0.66–0.77), with a cut-off value of 1299.6, sensitivity of 63%, and specificity of 70%. Lastly, SIRI had an AUC of 0.763 (95% CI: 0.71–0.81), with a cut-off value of 2.94, sensitivity of 69%, and specificity of 70%. These findings highlight the effectiveness of these inflammatory markers, particularly WBC and CRP, in diagnosing and predicting PTA in tonsillitis patients (Table 3).

Because a significant difference in gender distribution was observed between the groups, gender-adjusted binary logistic regression analyses were performed for the inflammatory markers with the highest diagnostic performance in ROC analysis (WBC, CRP, SII, and SIRI). After adjustment for gender, all four markers remained significantly associated with PTA. WBC (OR=1.417, 95% CI:1.312–1.530, p<0.001), CRP (OR=1.015, 95% CI:1.010–1.019, p<0.001), SII (OR=1.054 per 100-unit increase, 95% CI:1.031–1.078, p<0.001), and SIRI (OR=1.223, 95% CI:1.135–1.318, p<0.001) were all independently associated with PTA (Table 4).

In patients with PTA, the relationship between abscess size and inflammatory markers was analyzed using Pearson correlation. No significant correlation was observed between abscess size and any of the inflammatory junctive tools in identifying patients at increased risk for PTA and may facilitate earlier and more targeted clinical interventions.

Table 2: Comparison of inflammatory markers between groups

Table 3: Receiver operating characteristic (ROC) analysis results of inflammatory markers

Table 4: Gender-adjusted binary logistic regression analyses of inflammatory markers associated with peritonsillar abscess

The distinction between PTA and uncomplicated tonsillitis remains a significant diagnostic challenge in otolaryngology practice. Radiological imaging modalities, particularly ultrasound and CT, are frequently employed in the diagnosis of peritonsillar abscess and in the evaluation of its potential complications[13]. However, differentiating early-stage PTA from other infectious conditions, such as tonsillitis or peritonsillar phlegmon, often poses a clinical challenge3. Early identification of PTA allows for more controlled and timely patient management, enabling the timely initiation of appropriate treatment. This may help reduce the risk of complications and avoid unnecessary invasive interventions. Therefore, integrating inflammatory markers into the diagnostic process can provide significant value in ensuring an accurate diagnosis at an early stage and help prevent unnecessary imaging or invasive interventions.

Physical examination findings, especially in early-stage cases, may not be adequate on their own to establish a definitive diagnosis[6]. Given the limitations of clinical examination, laboratory markers have gained increasing attention due to their potential to facilitate early diagnosis. In this context, Spiekermann et al. have reported that serum and saliva S100A8/A9 levels could be a useful diagnostic tool for distinguishing between PTA and acute tonsillitis during emergency outpatient consultations[14]. Yüksel et al. have suggested that the CRP/albumin ratio could be a prognostic score for predicting the transformation of acute tonsillitis into a PTA[15]. Additionally, another study has demonstrated that the pan-immune inflammation value is an effective marker for predicting the severity and potential complications of PTA cases[16]. Several studies have reported that mean platelet volume levels are statistically significant in patients with PTA and may help distinguish PTA from uncomplicated tonsillitis[9,10,17].

Our findings are consistent with previous studies showing higher WBC and CRP levels in PTA patients compared to tonsillitis patients, thereby supporting the validity of our findings[12,18]. However, studies indicating that WBC and CRP can be used as predictive markers for PTA are quite limited, and this highlights the significant contribution of our study to the literature. In the study by Şentürk et al., it was reported that WBC and CRP levels were significantly higher in the pre-treatment PTA group compared to the post-treatment group[10]. Additionally, Menekşe et al. demonstrated that in complicated PTA cases, WBC and CRP levels were significantly higher compared to those in uncomplicated cases[16]. This suggests that WBC and CRP, beyond their diagnostic role, can also serve as important parameters for monitoring inflammation in the assessment of PTA treatment follow-up and prognosis. However, contrary to our findings, some studies have reported that WBC and CRP do not show a significant difference between tonsillitis and PTA, and even when a significant difference is observed, these markers may not be used as predictive markers[15,17,19]. These discrepancies across studies may be attributed to differences in study design, patient selection criteria, and the timing of laboratory measurements, which can significantly influence inflammatory marker levels. Therefore, our study provides additional evidence supporting the diagnostic utility of WBC and CRP, particularly when combined with clinical findings, and reinforces their clinical relevance in contemporary PTA management. In contrast to previous reports, the relatively large sample size and the inclusion of multiple inflammatory indices in our study may have contributed to a more robust assessment of their diagnostic value.

In our study, SII and SIRI were also found to be significantly higher in the PTA group compared to the tonsillitis group. The AUC value for SII was calculated as 0.719, while the AUC for SIRI was 0.763. These indices offer a more comprehensive assessment of systemic inflammation by combining counts of neutrophils, monocytes, platelets, and lymphocytes. The prognostic and predictive efficacy of these markers has previously been demonstrated in various inflammatory diseases and malignancies[20-23]. Koder et al. highlight the potential of SII as a valuable biomarker in distinguishing between acute tonsillitis and PTA.[11] Unal et al. have supported this view with their reported findings[9]. Elevated SII and SIRI levels in PTA patients reflect an enhanced inflammatory response associated with abscess formation. However, the sensitivity and specificity of these markers were found to be lower compared to WBC and CRP. This suggests that while SII and SIRI provide supportive clinical value, they cannot replace traditional inflammatory markers.

In contrast, PLR did not show a significant difference between the two groups. This finding contradicts some previous studies that suggested PLR could be a potential marker for distinguishing bacterial infections[11,24]. The lack of a significant difference in PLR in our study may be attributed to the fact that PTA involves localized neutrophilic activation rather than a systemic platelet response.

A significant difference in gender distribution was observed between the PTA and tonsillitis groups. Therefore, gender-adjusted binary logistic regression analyses were performed to evaluate whether the observed associations between inflammatory markers and PTA were independent of potential demographic differences. After adjustment for gender, WBC, CRP, SII, and SIRI all remained significantly associated with PTA. These findings indicate that the diagnostic value of these inflammatory markers is not solely attributable to differences in gender distribution between the study groups. Thus, both traditional inflammatory markers and composite inflammatory indices appear to provide clinically relevant information for distinguishing PTA from uncomplicated tonsillitis. Another noteworthy finding is the lack of a significant correlation between abscess size and inflammatory markers. This suggests that while inflammatory markers are valuable in diagnosing PTA, they may not directly reflect the size of the abscess.

The findings have significant implications for clinical practice. Identifying reliable inflammatory markers for distinguishing PTA from tonsillitis can enable early diagnosis, allowing for timely intervention and reducing the risk of severe complications such as parapharyngeal abscess, retropharyngeal abscess, airway obstruction, and Lemierre syndrome. However, these markers should be interpreted in conjunction with clinical and radiological findings rather than used as standalone diagnostic tools. These findings should be interpreted in the context of existing literature, as variations across studies highlight the complexity of inflammatory marker behavior in different clinical settings.

The detailed evaluation of a wide range of inflammation markers in our study constitutes a strength of our study. However, our study also has certain limitations. Due to the retrospective design, establishing a causal relationship is challenging, and the inclusion of a study population from a single tertiary care hospital may limit the generalizability of the results. Additionally, although significant differences in inflammatory markers were observed between PTA and tonsillitis patients, the potential influence of confounding factors such as bacterial virulence variations and host immune response should be further investigated. Future research is crucial for further developing predictive models and enhancing diagnostic accuracy in clinical practice.

Results

Conclusion

In conclusion, our study has demonstrated the diagnostic value of various inflammatory markers in distinguishing PTA from uncomplicated tonsillitis. WBC and CRP emerged as the most diagnostically accurate biomarkers, while SII and SIRI were identified as supportive markers. Our findings highlight that integrating laboratory markers into clinical decision-making processes may enhance early diagnosis and optimize patient management.

Conclusion