Pseudoballs as a distinct endotype of sinonasal bioballs

Abstract

Background Fungal ball has been known as a noninvasive subtype of chronic rhinosinusitis (CRS). Recently, other endotypes of sinonasal bioballs, which we reported as bacterial balls and mixed balls.

Objectives This study aimed to investigate the pseudoball as a distinct endotype of sinonassal bioballs.

Methods This study included 41 CRS patients with suspected fungal balls who underwent functional endoscopic sinus surgery (FESS) from January 2020 to November 2022. All fungus-like biomaterials were stained with Hematoxylin-Eosin, Gomori-Methenamine-Silver (GMS), and Gram stains. Diagnosis of pseudoballs was made when both GMS and Gram staining were negative. Clinical and computed tomography (CT) findings were compared between fungal balls and pseudoballs.

Results Four endotypes of sinonasal bioballs were identified: fungal balls (56.1%), mixed balls (26.8%), pseudoballs (12.2%), and bacterial balls (4.9%). During FESS, the pseudoballs had heterogeneous gross features with a gel-like or semi-solid consistency and yellow-to-gray colors. Histopathology of the pseudoballs showed a matrix with thick acellular mucous material without any fungi or bacteria. When compared with fungal balls, all pseudoballs cases were immunocompetent (100%) and prone to involvement of the posterior ethmoid sinus (60%, p = 0.01) in CT scans.

Conclusions The pseudoballs were dual-negative in GMS and Gram staining and showed distinct clinical and radiological characteristics as a different endotype.

背景 真菌球被认为是慢性鼻窦炎 (CRS) 的一种非侵袭性亚型。近年来, 我们报道了其它类型的鼻窦生物球, 例如细菌球和混合球。

目的 本研究旨在探讨作为鼻窦生物球的一种独特内型的假球。

方法 本研究纳入了 41 例疑似真菌球的 CRS 患者。这些患者于 2020 年 1 月至 2022 年 11 月接受了功能性内镜鼻窦手术 (FESS)。所有真菌样生物材料均采用苏木精-伊红染色、Gomori-六胺-银 (GMS) 染色和革兰氏染色。当GMS 和革兰氏染色均为阴性时, 诊断为假球。比较了真菌球和假球的临床和计算机断层扫描 (CT) 表现。

结果 鼻窦生物球可分为四种内型: 真菌球(56.1%)、混合球(26.8%)、假球(12.2%)和细菌球(4.9%)。在FESS 过程中, 假球具有异质性大体特征, 呈凝胶状或半固体状, 颜色为黄灰色。假球的组织病理学检查显示基质中含有厚厚的无细胞黏液物质, 不含任何真菌或细菌。与真菌球相比, 所有假球病例免疫功能均正常(100%), 且 CT 扫描显示后筛窦易受累(60%, p = 0.01)。

结论 假球在 GMS 和革兰氏染色中均为阴性, 并表现出独特内型的临床和放射学特征。