Histochemical, immunohistological and scanning electron microscope analysis of tissue retained on spontaneously extruded ventilation tubes

Abstract

The aim of this study was to analyse the tissue surrounding prematurely extruded ventilation tubes (grommets). Thirty-one ventilation tubes, including 21 Shah and six Shepherd tubes, that had been extruded naturally into the ear canal were examined. After formalin fixation, material adhering to the tubes was retrieved and processed to paraffin wax. Five tubes were processed for scanning electron microscope (SEM) analysis. Sections were stained using histochemical methods for collagen, keratin and keratohyaline. In addition, the presence of collagen (type I and III), keratin, vimentin, fibronectin, tenascin, factor VIII-related antigen, CD31 and CD45 was tested for by immunohistochemistry. Results showed that all specimens consisted of an acellular fibrous material, oriented in concentric rings parallel to the tube surface that was often associated with small collections of CD45+ inflammatory cells. Two specimens contained collagen that was detectable by histochemical and immunohistological methods. Twelve specimens contained identifiable desquamated epithelial cells containing keratin and keratohyaline. Only one specimen stained positively for connective tissue markers (vimentin, fibrous fibronectin, tenascin) or showed the presence of vascular epithelium. SEM revealed adherent clusters or sheets of plate-like structures, consistent with the presence of epithelial squames, on three of the five ventilation tubes examined. It is concluded that tissue retained on extruded grommets consists of orthokeratinitizing epithelium infiltrated by inflammatory cells, a finding that is consistent with the theory that tube extrusion occurs as a result of squamous epithelial proliferation, medial migration, differentiation and desquamation.

Failed Tube Extrusion is Not a Random Event in Children or Their Siblings

“…Because specimens showed some evidence of local inflammation, they suggested that tube extrusion occurred as a result of pressure created by chronic hyperplasia and inflammation causing elevation of the tube. Sammons et al 22 studied naturally extruded tympanostomy tubes by conventional histology and scanning electron microscopy. Such tubes are usually surrounded by concentric rings of keratin that encase them in squamous epithelium, with the most differentiated elements next to the surface of the implant.…”

Factors affecting the persistence of tympanic membrane perforation developed with the extubation of ventilation tube

“…Sammons et al demonstrated concentric rings of keratin usually surrounded the naturally extruded VTs; they suggested that chronic perforations were due to a failure in the normal healing process, and that healing was inhibited by the development of a mature rim around the perforation [12]. Therefore, perforations detected with spontaneous extrusion might be healing or might already have a mature rim around the perforation.…”

Development of a novel biodegradable drug‐eluting Ventilation tube for chronic otitis media with effusion

“…Up to 93% of children experience at least one episode of OME during their childhood, and 74% of them have three or more episodes. 8,9 Nonbiodegradable VTs have unpredictable duration of function, because they rely on the squamous epithelial accumulation of the tympanic membrane (TM) for extrusion. When patients fail medical and conservative treatment, tympanostomy and ventilation tube (VT) insertion are considered the standard treatment for recurrent OME.…”