Feline Esophagus

What It Is

"Feline esophagus" (also called ringed esophagus or trachealization) is an endoscopic/radiologic finding where the esophageal mucosa shows stacked circular rings or concentric transverse ridges, resembling the striped pattern of a cat's tail or the rings of a trachea. The term refers to the supposed endoscopic resemblance to a striped cat's coat.

Robbins Pathologic Basis of Disease, p. 707: "the esophageal mucosa can resemble stacked circular rings (referred to as feline esophagus because of supposed endoscopic resemblance to a striped cat's tail) with strictures and linear furrows."

Primary Association: Eosinophilic Esophagitis (EoE)

Feline esophagus is the hallmark endoscopic feature of Eosinophilic Esophagitis (EoE). It is one of the most characteristic findings alongside linear furrows and white exudates (eosinophilic abscesses).

Endoscopic Findings in EoE

Feature	Description
Feline/ringed esophagus	Stacked circular mucosal rings (fixed or transient)
Trachealization	Same as above - rings resemble a trachea
Linear furrows	Vertical longitudinal lines
White exudates/plaques	Whitish papules = eosinophilic abscesses
Edema/pallor	Decreased vascular markings
Strictures	Narrowing of esophageal lumen
Narrow-caliber esophagus	Long-segment narrowing (small-caliber esophagus)
Crepe-paper mucosa	Mucosal fragility

Important: Endoscopic findings are normal in at least one-third of EoE patients - normal endoscopy does not exclude the diagnosis. - Sleisenger & Fordtran's GI and Liver Disease

Histology of EoE (the diagnostic standard)

Histology comparing reflux esophagitis (A) with scattered eosinophils vs. eosinophilic esophagitis (B) showing dense eosinophilic infiltration

Fig: (A) Reflux esophagitis - scattered intraepithelial eosinophils with mild basal zone expansion. (B) EoE - numerous intraepithelial eosinophils (dense sheets).

The cardinal histologic feature is:

>15 eosinophils per high-power field (x40) - large numbers of intraepithelial eosinophils, predominantly superficial, forming clusters and sheets
Intercellular edema
Basal hyperplasia and papillary lengthening

Sensitivity of biopsy: a single specimen has only 55% sensitivity; taking 5 biopsy specimens increases sensitivity to 100% (due to patchy distribution). - Sleisenger & Fordtran

Rings vs. Trachealization: Key Distinction

From the Clinical GI Endoscopy textbook, rings in EoE are classified and must be distinguished from transient plications (which can mimic feline esophagus). Rings are best appreciated when the esophagus is fully insufflated during endoscopy.

Fixed rings (fibrostenotic) - also called concentric rings, corrugated esophagus, trachealization - graded by severity
Transient rings - may be peristalsis-related; easily confused with true feline/ringed esophagus

Differential Diagnosis of Feline Esophagus

While most strongly associated with EoE, feline esophagus can also appear in:

GERD - overlap exists; ringed appearance can occur with chronic reflux
Transient mucosal folds - peristaltic contractions can transiently produce a striped/ringed pattern on fluoroscopy (original radiologic description)
Hiatal hernia-related changes

Pathogenesis of EoE

EoE is an immune-mediated (Th2-driven) allergic disorder:

Associated with atopy (atopic dermatitis, allergic rhinitis, asthma)
Food antigens (especially cow's milk) trigger IgE- and non-IgE-mediated eosinophilic infiltration
Mast cells and IL-4/IL-13 signaling are implicated
Incidence has increased over the last 20 years in parallel with other Th2-mediated allergic disorders

Clinical Features of EoE

Feature	Children	Adults
Presentation	Reflux, vomiting, food refusal, failure to thrive	Dysphagia, food impaction, chest pain
Demographics	Young children, predominantly male	Can occur at any age
Atopy	Common	Common

Diagnosis of EoE

Suggestive history (dysphagia, food impaction)
Esophageal eosinophilic infiltrate on biopsy (>15 eos/hpf)
Exclusion of GERD (normal pH monitoring or failure to respond to high-dose PPIs)
Multiple biopsies (at least 5) for adequate sensitivity

Treatment

Dietary: Empiric elimination of cow's milk and dairy (first-line dietary approach); guided elimination based on skin patch/IgE testing
Pharmacologic: PPIs, topical corticosteroids (swallowed budesonide/fluticasone)
Biologic: IL-4/IL-13 receptor antagonists (dupilumab) are beneficial
Endoscopic: Dilation of strictures - must be done in small increments to reduce risk of mucosal tears and perforation; does not reduce inflammation
Robbins, Cotran & Kumar Pathologic Basis of Disease; Schwartz's Principles of Surgery, 11th ed.; Sleisenger & Fordtran's GI and Liver Disease

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