Retropharyngeal abscess in adults: case report and literature review

Introduction

Background

Retropharyngeal abscess (RPA) is a potentially life-threatening deep neck infection that requires prompt diagnosis and treatment because of its risk of rapid progression and severe complications. Although it occurs predominantly in children, RPA is uncommon in adults and is therefore often overlooked in the differential diagnosis of neck pain, fever, and odynophagia. Delayed diagnosis may result in life-threatening complications, including airway obstruction, descending necrotizing mediastinitis, pericarditis, and pleuritis (1).

The retropharyngeal space extends from the skull base to the mediastinum. It is bounded anteriorly by the bucco-pharyngeal fascia, laterally by the carotid sheath, and posteriorly by the prevertebral fascia. The alar fascia divides this space into the true retropharyngeal space and the so-called “danger space”, which provides a direct pathway for the spread of infection into the mediastinum (1). Retropharyngeal lymph nodes, located within the suprahyoid portion of this space, drain the nasopharynx, adenoids, posterior paranasal sinuses, and middle ear. These lymph nodes undergo physiological involution during childhood, explaining why RPAs are considerably more common in children than in adults (2).

Rationale and knowledge gap

In children, RPA most commonly develops following suppurative adenitis of the retropharyngeal lymph nodes after an upper respiratory tract infection (3). In contrast, adult RPA is rare and is usually associated with predisposing factors such as immunosuppression, diabetes mellitus, human immunodeficiency virus (HIV) infection, malignancy, tuberculosis, foreign body ingestion (e.g., fish or chicken bones), or iatrogenic trauma following endotracheal intubation, nasogastric tube placement, or laryngoscopy (4). The infection is typically polymicrobial, involving aerobic organisms such as Staphylococcus spp. and Streptococcus spp., as well as anaerobes including Fusobacterium and Bacteroides spp.

Patients with RPA commonly present with fever, odynophagia, pharyngodynia, neck pain or stiffness, dysphagia, torticollis, and trismus. However, the absence of pathognomonic clinical findings frequently delays diagnosis. Contrast-enhanced computed tomography (CT) is the imaging modality of choice because it accurately identifies the abscess, defines its extent, and detects potential complications. Initial management consists of prompt intravenous broad-spectrum antibiotic therapy, while surgical drainage is indicated in patients with airway compromise, failure of conservative treatment, or extensive collections. The surgical approach may be transoral or transcervical depending on the location and extent of the abscess. When airway protection cannot be safely achieved, tracheostomy may be required before surgical drainage (5).

Objective

We report the case of a 23-year-old immunocompetent woman who developed an RPA despite the absence of recognized predisposing factors. This case highlights that, although uncommon, RPA may occur even in otherwise healthy adults and should not be excluded solely because traditional risk factors are absent. To place this case in context, we also performed a narrative review of the literature. The literature search was conducted using the PubMed and Scopus databases with combinations of the keywords “retropharyngeal abscess”, “adult”, “deep neck infection”, and “retropharyngeal infection” linked by the Boolean operators AND and OR. English-language articles reporting adult cases, case series, reviews, and studies addressing the etiology, diagnosis, microbiology, imaging, and management of adult RPA were considered. Additional relevant publications were identified through manual screening of the reference lists of the retrieved articles. We present this article in accordance with the CARE reporting checklist (available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-2026-0028/rc).

Case presentation

A Caucasian 23-year-old female patient came to our observation in March 2025 with a 15-day history of right-sided cervical swelling, neck stiffness, fever, and odynophagia despite 5 days of oral amoxicillin/clavulanate prescribed by her general practitioner. Her medical history was remarkable for recurrent tonsillitis, with the last episode occurring approximately one month before admission, and previous right hip and hand prosthetic surgery following a road traffic accident in 2022. She denied recent endotracheal intubation, upper gastrointestinal instrumentation, or foreign body ingestion. She had no history of diabetes mellitus, HIV infection, malignancy, tuberculosis, immunosuppressive therapy, organ transplantation, or any other condition associated with immunodeficiency. Therefore, no identifiable predisposing risk factors for adult RPA were identified. On physical examination, right-sided cervical swelling was evident, without erythema or other inflammatory changes of the overlying skin. The exact dimensions of the swelling were not recorded at presentation. Oropharyngeal examination showed hypertrophic palatine tonsils and good dental health. Flexible fiberoptic nasopharyngolaryngoscopy was performed to evaluate the upper aerodigestive tract and revealed medialization of the right lateral oropharyngeal wall and bulging of the posterior pharyngeal wall (Figure 1). Hypertrophic and hyperemic adenoid tissue, consistent with acute adenoiditis, was also observed in the nasopharynx. No other relevant abnormalities of the upper aerodigestive tract were identified. Blood tests on admission revealed elevated white blood cells (WBCs 28.97 ×10³ µL, neutrophils 86.8%), and C-reactive protein (CRP 54.4 mg /L), indicative of infection. A contrast-enhanced neck CT revealed a predominantly right-sided RPA extending from the nasopharynx to the C2–C3 level. The collection measured approximately 79 mm × 30 mm × 6 mm (craniocaudal × transverse × anteroposterior) and showed partial extension into the right lateral pharyngeal space (Figure 2). The patient was therefore started on intravenous piperacillin/tazobactam (4.5 g every 6 hours) and underwent emergency surgical treatment. Given the extensive craniocaudal extension of the abscess, its partial involvement of the right lateral pharyngeal space, persistent symptoms despite prolonged oral antibiotic therapy, and the potential risk of further extension into the deep neck spaces, emergency surgical drainage was indicated. Drainage of the RPA was therefore performed via cervicectomy, followed by placement of a negative-pressure drain. Pus collected during surgery was negative for bacterial and fungal cultures, likely due to prior antibiotic use. The patient received intravenous piperacillin/tazobactam (4.5 g every 6 hours) for 8 days, followed by oral amoxicillin/clavulanate for 10 additional days after discharge. The postoperative course was uneventful. The negative-pressure drain was removed on postoperative day 5, and the patient was discharged 8 days after admission, in March 2025, with complete resolution of symptoms at follow-up (Figure 3). All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Figure 1 Flexible fiberoptic nasopharyngolaryngoscopic view showing medialization of the right lateral oropharyngeal wall and bulging of the posterior pharyngeal wall associated with the RPA. RPA, retropharyngeal abscess.

Figure 2 Neck CT showing right RPA extending from the nasopharynx up to the C2–C3 level (red line) with partial involvement of the lateral-pharyngeal space mainly on the right (red arrows). (A) Sagittal scan; (B) axial scan at oropharyngeal level; (C) axial scan at hypopharyngeal level. CT, computed tomography; RPA, retropharyngeal abscess.

Figure 3 Clinical timeline of the present case. The timeline summarizes the relevant medical history and the chronological clinical course, including symptom onset, outpatient antibiotic therapy, hospital admission, diagnostic evaluation, surgical treatment, postoperative management, and outcome. CRP, C-reactive protein; CT, computed tomography; WBC, white blood cell.

Discussion

Key findings

The present case describes an extensive RPA in a 23-year-old immunocompetent woman without recognized predisposing factors. Unlike the typical adult presentation, which is frequently associated with immunocompromised states, tuberculosis, foreign body ingestion, or iatrogenic trauma, our patient had none of these conditions. Nasopharyngoscopy revealed hypertrophic and hyperemic adenoid tissue consistent with acute adenoiditis, which was considered the most likely source of infection. Despite the extensive craniocaudal involvement of the abscess and partial extension into the right lateral pharyngeal space, combined intravenous antibiotic therapy and transcervical surgical drainage resulted in complete clinical recovery without postoperative complications.

The main clinical message of this case is that RPA should not be excluded in young, otherwise healthy adults solely because conventional predisposing factors are absent. Furthermore, the case emphasizes the importance of contrast-enhanced CT in defining the extent of infection and guiding an individualized surgical approach.

Strengths and limitations

The main strength of this report is the detailed clinical, radiological, and therapeutic characterization of an uncommon RPA occurring in a young immunocompetent adult without recognized predisposing factors. Contrast-enhanced CT allowed accurate assessment of the extent of the collection and its involvement of adjacent deep neck spaces, supporting timely surgical decision-making. Furthermore, the combined medical and surgical approach resulted in an uneventful post-operative course and complete clinical recovery.

Nevertheless, several limitations should be acknowledged. The patient had received oral antibiotic therapy before hospital admission, which may have contributed to the negative bacterial and fungal cultures and prevented microbiological identification of the causative pathogen. Moreover, although nasopharyngoscopy revealed findings consistent with acute adenoiditis, its role as the source of the retropharyngeal infection remains presumptive rather than microbiologically demonstrated. From a diagnostic perspective, the nonspecific initial symptoms and previous outpatient antibiotic treatment may have contributed to delayed recognition of the condition. Finally, as this is a single case accompanied by a narrative rather than systematic review of the literature, the findings cannot be generalized and should primarily be interpreted for their clinical and educational value.

Comparison with similar research

Adult RPA differs from the pediatric form in both epidemiology and etiology. While RPA in children commonly results from suppurative involvement of retropharyngeal lymph nodes following upper respiratory tract infections, adult cases are more frequently associated with foreign body ingestion, trauma, immunocompromised states, tuberculosis, or iatrogenic procedures. Less commonly, infection may spread by contiguity from the pharynx or through lymphatic drainage from infected tissues (6).

Published series also suggest that adult RPA occurs more frequently in men and at an older age than in the present case. Harkani et al. reported five adult patients, with a male-to-female ratio of 3:2, and identified foreign body ingestion as the most common predisposing factor (7). Similarly, Sanz Sánchez et al., in a series of 33 adult patients, reported a male predominance (19 men and 14 women) and a mean age of 52 years (8). In contrast, our patient was a 23-year-old woman with no recognized predisposing factors. Nevertheless, the absence of an identifiable conventional etiology is not unprecedented: in the series by Sanz Sánchez et al., no clear cause was identified in 18 of 33 patients, whereas foreign body ingestion accounted for nine cases. Less frequent causes included esophageal perforation, peritonsillar abscess, local cocaine injection, and previous radiotherapy for head and neck cancer (8).

Microbiological findings in adult RPA are heterogeneous. In the series by Sanz Sánchez et al., cultures were obtained in 28 patients and identified organisms including Staphylococcus aureus, Streptococcus viridans, Fusobacterium, Streptococcus pyogenes, Pseudomonas aeruginosa, and Streptococcus milleri. Cultures were negative in eight patients; a finding potentially related to previous antibiotic treatment and consistent with our case (8). Miyazaki et al. similarly described aerobic and anaerobic microorganisms in two adult patients, supporting the polymicrobial nature of RPA (9).

Treatment strategies reported in the literature range from intravenous antibiotic therapy alone to combined medical and surgical management. In the series by Sanz Sánchez et al., 27 of 33 patients underwent surgical drainage, including 22 transcervical and five transoral procedures, whereas six patients were successfully treated with antibiotics alone (8). Harkani et al. also reported favorable outcomes using antibiotic therapy combined with drainage when indicated (7). The main characteristics of the adult RPA cases and series considered in our narrative review are summarized in Table 1.

Explanations of findings

Several features may explain the unusual presentation observed in our patient. Although no conventional predisposing factor for adult RPA was identified, nasopharyngoscopy demonstrated hypertrophic and hyperemic adenoid tissue consistent with acute adenoiditis. Considering the anatomical relationship between the nasopharynx, adenoid tissue, and retropharyngeal lymphatic drainage, contiguous or lymphatic spread from acute adenoid inflammation represents a plausible mechanism for abscess formation (6). Nevertheless, because no causative microorganism was isolated and a direct causal relationship could not be demonstrated, acute adenoiditis should be regarded as the most likely rather than a definitively proven source of infection.

The negative microbiological cultures may be explained, at least in part, by the oral amoxicillin/clavulanate therapy administered before hospital admission. Similar culture-negative cases following previous antibiotic exposure have been reported in the literature (8). Therefore, negative cultures should be interpreted cautiously and do not exclude an infectious etiology when clinical, laboratory, and radiological findings are strongly suggestive of RPA.

Contrast-enhanced neck CT played a central role in the diagnostic and therapeutic pathway. In addition to confirming the diagnosis, CT accurately demonstrated the marked craniocaudal extension of the collection and its partial involvement of the right lateral pharyngeal space. CT is considered the imaging modality of choice for RPA because it can define the extent of infection, identify involvement of adjacent deep neck spaces, detect potential complications, and reveal foreign bodies, with reported sensitivity ranging from 64% to 100% (4,10,11).

These anatomical findings also influenced the choice of surgical approach. Although abscess size may contribute to therapeutic decision-making, no universally accepted size threshold determines whether a transoral or transcervical approach should be used (4). Surgical planning should instead consider the location and extent of the collection, involvement of adjacent deep neck spaces, accessibility through the oral cavity, and airway status. In our patient, the extensive craniocaudal extension and partial involvement of the right lateral pharyngeal space favored transcervical drainage, which also allowed placement of a negative-pressure drain.

Implications and actions needed

This case has several practical implications. First, RPA should remain in the differential diagnosis of adults presenting with fever, odynophagia, cervical swelling, and neck stiffness even when traditional predisposing factors are absent. In particular, young age and an immunocompetent status should not lead clinicians to prematurely exclude this diagnosis.

Second, early contrast-enhanced CT should be considered when clinical findings raise suspicion of a deep neck infection, as accurate characterization of the location and extent of the collection is crucial for treatment planning. Finally, management should be individualized rather than based solely on abscess size. Airway status, response to antibiotic therapy, anatomical extent, involvement of adjacent deep neck spaces, and surgical accessibility should collectively guide the decision between conservative treatment and surgical drainage, as well as the choice of surgical approach (4,12,13).

Conclusions

Adult RPA is an uncommon but potentially life-threatening condition that may occur even in young, immunocompetent patients without recognized predisposing factors. In the present case, acute adenoiditis represented a plausible source of infection, although a definitive causal relationship could not be established. Early recognition, contrast-enhanced CT assessment, and individualized treatment based on clinical status and anatomical extent are crucial for appropriate management. This case reinforces the importance of including RPA in the differential diagnosis of adults presenting with compatible symptoms, regardless of the absence of traditional risk factors.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-2026-0028/rc

Peer Review File: Available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-2026-0028/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jeccm.amegroups.com/article/view/10.21037/jeccm-2026-0028/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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