Esophageal cysts are rare benign lesions.  

Malignant transformation is an extremely rare event occurring within esophageal cysts, adenocarcinoma being the most common histology.   

Squamous carcinoma has also been reported.

- Retention cyst or mucocele - Usually located in the lower esophagus  and is lined by squamous epithelium or cuboidal cells and is probably related to post-inflammatory cystic dilatation of excretary duct of submucosal esophageal gland.

- Duplication (developmental) cysts -Esophageal duplication cysts are rare congenital anomalies lined by esophageal, bronchial or gastric type epithelium.  60% of duplication cyst is located in the lower esophagus. Foregut duplications occur as a result of abnormal canalization of the foregut during intrauterine life.

  Site:  May be attached to the esophagus in a paraesophageal location or may be intramural.

- Inclusion cysts - Unilocular intramural cyst in the lower part of the esophagus, lined by squamous or columnar epithelium or ciliated columnar epithelium. 

Abstracts:

Intra-abdominal esophageal duplication cyst in an adult.Yonsei Med J. 2005 Dec 31;46(6):859-61.

A case of esophageal duplication cyst with a 13-year follow-up period.Endoscopy. 2005;37(9):870-2.

Case report: Squamous carcinoma in an oesophageal foregut cyst.Br J Radiol. 2003 May;76(905):343-6.

Clinicopathologic assessment of esophageal cysts--a report of 8 cases.Nippon Kyobu Geka Gakkai Zasshi. 1990 Jun;38(6):982-8.

Isolated intra-abdominal esophageal cyst. Case report and review of the literature.Am J Surg Pathol. 1996;20(4):476-9.

AN APPROACH TO THE  REPORTING  OF ESOPHAGEAL BIOPSIES

BARRETT'S   ESOPHAGUS   (INTESTINAL METAPLASIA  DYSPLASIA  &   ADENOCARCINOMA)

BENIGN TUMOURS AND  TUMOUR - LIKE CONDITIONS  OF  ESOPHAGUS

 1. SQUAMOUS PAPILLOMA OF THE ESOPHAGUS

 2. INFLAMMATORY FIBROID POLYP OF THE ESOPHAGUS

 3. LEIOMYOMA OF THE ESOPHAGUS

 4. GRANULAR CELL TUMOUR OF THE ESOPHAGUS

 5. ESOPHAGEAL CYSTS

 6. GLYCOGENIC ACANTHOSIS

 7.FIBROVASCULAR POLYPS

REPORTING  OF  ESOPHAGEAL  RESECTION SPECIMENS

SQUAMOUS  EPITHELIAL  DYSPLASIA INCLUDING SQUAMOUS CELL CARCINOMA IN-SITU OF THE ESOPHAGUS

SMALL CELL CARCINOMA OF THE ESOPHAGUS

DRUG  RELATED  LESIONS  OF  THE GASTROINTESTINAL TRACT