Carcinoid Tumor Arising in a Tailgut Cyst of the Anorectal Junction With Distant Metastasis: A Case Report and Review of the Literature

Abstract

Tailgut cyst is a rare congenital presacral lesion and is believed to arise from the persistent remnants of the postanal gut. Malignancy occurring in a tailgut cyst is extremely rare, and to our knowledge only 5 cases of carcinoid tumor arising in a tailgut cyst have been reported in the literature to date. We report a sixth case of carcinoid tumor arising in a tailgut cyst. The patient was a 41-year-old woman who presented with perianal pain. Sigmoidoscopy showed a 2-cm submucosal mass located 4 cm above the anal verge. The mass was a multilocular cyst with gray-tan solid portions. The cyst was lined by ciliated columnar, squamous, and transitional epithelia with small foci of carcinoid tumor in the cystic wall. The carcinoid tumor showed a trabecular growth pattern with uniform oval or round cells containing fine chromatin and positive immunoreactivity for chromogranin, synaptophysin, and cytokeratin. This case was unique because the tumor occurred at the anorectal junction, not in the retrorectal space, and unlike previously reported cases showed aggressive behavior and distant metastases.

An Unusual Perianal Presentation of a Tailgut Cyst

“…A large majority of tailgut cysts are benign; however, malignant transformation, although rare, has been reported in several cases. They include adenocarcinomas, carcinoid tumors, neuroendocrine carcinomas, endometrioid carcinomas, adenosquamous carcinomas, squamous cell carcinomas, and sarcomas, in decreasing order of frequency [ 1 - 6 ]. Evidence suggests that the dysplasia-carcinoma sequence, initially established in the colon, can also exist in tailgut cysts [ 6 ].…”

“…However, it is not recommended as there are chances that it may contain only fibrous tissue without epithelia or only one epithelium, and the malignant foci may not be sampled. Additionally, there is a risk of infection, and malignant cells can spill into the abdominal cavity and lead to tumor spread [ 1 , 2 , 5 ].…”

“…Tailgut cysts or retrorectal cystic hamartomas are rare, congenital, hamartomatous lesions that arise from the persistent embryological remnants of the postanal gut (hindgut) that fail to regress completely [ 1 ]. They occur in all age groups, more commonly in middle-aged women and mostly in the retrorectal (presacral) space.…”

Malignant Transformation of Tailgut Cyst to Squamous Cell Carcinoma, a rare case with poor outcome

“…The infectious process like repeated urinary tract infection, abscess, and fistula formation may also occur with symptoms including high fever, pain, and frequent micturition. (5)(6)(7)(8)(9)(10)(11) Differential diagnoses that should be considered for retro-rectal masses include anal gland cyst, duplication cyst, endometriotic cyst, sacral meningocele, or pilonidal sinus. ( 4)…”

“…(9) CT and MRI are required to diagnose and characterize differential diagnosis and treatment strategies. (10,11) Malignant and benign lesions show different characteristics on MRI examination, especially on T2-weighted images (12). Sarkar et al believed that radiological examination could contribute to diagnosing cystic lesions in the presacral space; however, the definitive diagnosis can only be achieved by surgical exploration and histological examination (13).…”