Approach to a Unilateral Sinonasal Mass in a Pre-Adolescent Male: An Unusual Presentation of Allergic Fungal Rhinosinusitis

Abstract

This case report presents the clinical evaluation of an 11-year-old boy with a unilateral polypoid nasal mass causing nasal obstruction, facial asymmetry, and intermittent epistaxis. His clinical picture raised concerns of a juvenile nasopharyngeal angiofibroma; however, further imaging and histopathological evaluation ultimately confirmed the diagnosis of allergic fungal rhinosinusitis (AFRS). Although this patient was younger in age than those traditionally associated with AFRS, classical features present on both computed tomography (CT) and magnetic resonance imaging (MRI) aided in his diagnosis and management. This case underscores the importance of a comprehensive diagnostic approach when evaluating unilateral sinonasal masses in paediatric patients, specifically in atypical presentations where the diagnosis of AFRS may not initially be considered. It highlights the critical role of imaging as a diagnostic tool, specifically CT and MRI, which were pivotal in the work-up and management of this case. Additionally, the need for caution during biopsies of sinonasal masses in children is emphasised, as there is potential for catastrophic bleeding in vascularised masses such as juvenile nasopharyngeal angiofibroma. This case demonstrates that AFRS can occur in younger children, highlighting the need to include this in the differential diagnosis, even in patients outside of the traditionally described age group.

1. Introduction

Allergic fungal rhinosinusitis (AFRS) is a non-invasive fungal sinusitis associated with chronic non-IgE-mediated allergic mucosal inflammation [1,2,3]. It is a subtype of eosinophilic Type 2 chronic rhinosinusitis (CRS), where inflammation results from the activation of innate immune cells, with eosinophilic chemotaxis acting in response to extra-mucosal fungi, rather than an IgE-mediated reaction [3,4,5]. AFRS constitutes up to 72% of fungal rhinosinusitis cases, occurring in immunocompetent individuals [1,4,6,7].

Diagnosing AFRS relies on the Bent–Kuhn criteria, where nasal polyposis, extra-mucosal fungal hyphae, eosinophilic mucin, Type 1 hypersensitivity to fungi, and characteristic radiological findings encompass the major criteria [1,5]. This criterion is limited as only 90% of patients have IgE-mediated hypersensitivity to fungal antigens. Additional features include bony erosion, Charcot–Leyden crystals, peripheral eosinophilia, disease unilaterality, immunocompetence, and atopy [1]. The clinical presentation may mimic other unilateral sinonasal masses, such as juvenile nasopharyngeal angiofibroma (JNA), particularly in cases of peri-adolescent males presenting with recurrent epistaxis. This case examines an 11-year-old male who presented with a unilateral sinonasal mass.

2. Detailed Case Description

An 11-year-old male presented to the Otorhinolaryngology outpatient clinic at Tygerberg Hospital with a 1-year history of left-sided nasal obstruction, hemifacial asymmetry, and recurrent self-aborting epistaxis. There was no significant medical history, including no mucopurulent nasal discharge, facial pain, or cough; no exposure to environmental allergens; and no family history of atopy.

On examination, he was a healthy child with facial asymmetry, including left pre-maxillary fullness and proptosis, but preserved visual acuity, pupil reactivity, and extra-ocular muscle function. Anterior rhinoscopy revealed nasal polyps filling the left nasal cavity, deviating the nasal septum to the right lateral nasal wall.

Due to the slowly progressive nature, patient age, and history of epistaxis, there was concern for a JNA. Imaging was therefore performed to investigate the nature of the lesion prior to tissue sampling due to risk of excessive bleeding, should it be a highly vascular tumour.

2.1. Imaging

Computed tomography (CT) imaging confirmed unilateral sinonasal opacification with bone expansion and remodelling, as well as left cribriform plate and lamina papyracea dehiscence—see Figure 1. Axial CT images showed symmetry of the pterygopalatine fossa bilaterally—see Figure 2. A subsequent MRI revealed typical features of AFRS—see Figure 3. These findings, alongside the clinical presentation guided the decision for surgical intervention.

2.2. Management and Outcome

The patient underwent left-sided endoscopic sinus surgery, where copious inspissated allergic mucin was identified (Figure 4 and Figure 5). A histopathologic examination of the polyps confirmed eosinophilic polypoid respiratory mucosa with Charcot–Leyden crystals and non-invasive Aspergillus and Candida species on histochemical staining. These confirmed the diagnosis of allergic fungal rhinosinusitis. The patient was initiated on systemic corticosteroids and intranasal corticosteroids in saline rinses to manage chronic inflammation. Postoperative follow-up showed the resolution of nasal obstruction and rhinorrhoea, as well as improved facial symmetry. Although skin prick testing excluded hypersensitivity to fungal antigens, the clinical and histological findings were definitive for AFRS.

3. Discussion

Nasal polyps in children are rare, with a prevalence of 0.1% in individuals under the age of 10 [2]. Their presence should encourage a thorough evaluation to exclude midline congenital skull-base defects, benign tumours, cystic fibrosis, and primary ciliary dyskinesia [2,8].

AFRS is a subtype of chronic rhinosinusitis, with nasal polyps (CRSwNP) being associated with Type 2 inflammation. The aetiology of CRSwNP is multifactorial, involving an impaired interaction between environmental factors including fungi, mucosal barrier breakdown, and chronic inflammation. This chronic inflammatory pattern is categorised into 2 endotypes—Type 2 and non-Type 2 [9].

Type 2 inflammation involves specific cytokines IL4, IL5, IL13, and IgE, which initiate the infiltration of eosinophils and mast cells into the sinonasal mucosa [1,9]. This leads to goblet cell hyperplasia, epithelial barrier disruption, and fibrin deposition, producing polyps [1]. Individuals with Type 2 CRS have a higher propensity for resistance to standard treatments and exhibit polyp-related phenotypes [1].

AFRS has a higher incidence and earlier age onset in warmer climates [4,5,6]. The American literature reports a mean onset age of 13–21.9 years [5], whereas the European literature reports an older age of 37.88–45.71 years [6]. There is male predominance in younger patients, shifting to female predominance in adults [5]. Although this patient was a male, he falls outside of this traditionally described age group for AFRS.

Radiographic imaging aids in diagnosis and surgical planning. Non-contrast CT scans show hyperdensities in the sinuses with bony expansion, and unilaterality in 70% of paediatric cases [1,5,7]. The hyperdensities result from the calcium, iron, magnesium, and manganese that are found in fungal deposits [1,7]. Gadolinium-contrasted MRI is useful in assessing intracranial or intra-orbital extension and may show characteristic hypo-intensities from allergic mucin on T2W sequences [1,7].

The management of AFRS is primarily surgical [1,5,6]. Surgery clears allergic mucin containing the inciting fungal debris and opens sinus drainage pathways while preserving normal tissue to maintain mucociliary clearance [1,5]. Medical treatments aim to suppress eosinophilic inflammation, utilising oral corticosteroids followed by intranasal saline douches with topical corticosteroids [6]. Long-term management may include both corticosteroids and immunotherapy, although the role of immunotherapy in AFRS requires further research [1,5,6].

This case underscores the importance of comprehensive diagnostic evaluation for sinonasal masses in paediatric patients, emphasising the need to consider AFRS as a differential in younger age groups.