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Special Feature
January 2012

Image of the Month—Diagnosis

Arch Surg. 2012;147(1):94. doi:10.1001/archsurg.2011.702b
Answer: Low-Grade Neuroendocrine Carcinoma Arising From a Tailgut Cyst

The final pathologic diagnosis was low-grade neuroendocrine carcinoma arising from a tailgut cyst. At the initial 3-month follow-up, the patient was doing well, with no signs of recurrence on physical examination and transrectal ultrasonography. His follow-up will consist of physical examination and transrectal ultrasonography every 3 months for the first year, every 6 months for the second, and yearly after that for a total of 5 years. Computed tomographic scan of the abdomen and pelvis will be obtained every year for 5 years. Regular colonoscopy protocol will be followed as per average-risk patients.

Tailgut cysts, or cystic hamartomas, are rare developmental cysts derived from tailgut remnants, an embryological precursor of the gastrointestinal system, thus explaining the common finding of glandular columnar epithelium within.1 The differential diagnoses include other congenital developmental (epidermoid cysts, dermoid cysts, and teratomas) and miscellaneous (chordomas, anterior meningocele, rectal duplications, and adrenal rest tumors) cystic lesions, inflammatory lesions (granulomas and abscesses), neurogenic neoformations (neurofibromas, neurolemmomas, ependymomas, ganglioneuromas, and neurofibrosarcomas), osseous tumors (osteomas, osteogenic sarcomas, sacral bone cysts, and Ewing tumor), and other neoplastic lesions (metastases, lymphangiomas, desmoid tumors, leiomyomas, and fibrosarcomas).2 Congenital lesions account for 55% to 70% of retrorectal lesions, and 60% of them are developmental cysts.3 Tailgut cysts can occur at any age but are more frequent in middle-aged women and most of the time are asymptomatic and incidentally diagnosed by routine physical examination or imaging studies obtained for nonspecific and often unrelated symptoms.4 Malignant transformation is unusual but the development of adenocarcinomas, carcinoids, squamous cell carcinomas, and sarcomas has been described.5 Digital rectal examination can provide essential information on the location, consistency, and mobility of the lesion, while endoscopic ultrasonography, computed tomographic scan, and magnetic resonance imaging are valuable tools in defining texture, extent, and relationships with surrounding structures of the lesion, the latter being the diagnostic imaging tool of choice.1 The role of transrectal or presacral needle biopsy is controversial because of the low likelihood of obtaining a significant sample for an adequate diagnosis, along with the potential risk of tumor seeding.6 A primary carcinoid tumor arising in a retrorectal tailgut cyst is a rare finding, with only 12 cases previously reported in the literature.5,7 Neuroendocrine carcinomas arising in tailgut cysts have a real malignant potential, as the occurrence of distant metastases has been reported in the literature.8 Besides the oncological concerns, the need for surgical excision of tailgut cysts resides in the potential for infection and fistulization.9 Surgical resection is the keystone in the management of all retrorectal tumors, aiming to excise the mass intact and surrounded by macroscopically intact tissue. For low lesions (below the fourth sacral element), a posterior approach is preferred to the transabdominal route to better assess local invasion without violating the rectal wall, unless it is involved.10 As confirmed in this case, a parasacrococcygeal approach with resection of the coccyx provides optimal exposure, thus facilitating radical en bloc resection of the tumor, sparing the uninvolved surrounding structures, with minimal surgical trauma and morbidity and fast recovery.

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Article Information

Correspondence: Alessandro Fichera, MD, 5841 S Maryland Ave, MC 5095, Chicago, IL 60637 (afichera@surgery.bsd.uchicago.edu).

Accepted for Publication: April 27, 2011.

Author Contributions:Study concept and design: Zoccali, Hart, and Fichera. Acquisition of data: Zoccali. Drafting of the manuscript: Zoccali and Fichera. Critical revision of the manuscript for important intellectual content: Hart and Fichera. Study supervision: Hart and Fichera.

Financial Disclosure: None reported.

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