A carcinoembryonic antigen-secreting adenocarcinoma arising in tailgut cyst: clinical implications of carcinoembryonic antigen

Abstract

Tailgut cysts (TGCs) are rare congenital cysts that occur in the retrorectal or presacral spaces. Although most tailgut cysts have been reported as benign, there have been at least 9 cases associated with malignant change. We report herein on an unusual case of a 40-year-old woman with a carcinoembryonic antigen (CEA)-producing adenocarcinoma arising within a TGC who underwent surgical resection and local radiation therapy. Despite the complete resection, metastatic adenocarcinoma developed five months after surgery. CEA-producing adenocarcinoma from a TGC is extremely rare and only two cases, including this case, have been reported in the English medical literature. Besides CEA, the serum levels of CA 19-9 became markedly elevated in this patient. Given that the serum CEA level decreased to the normal range after complete resection of tumor and that the tumor recurrence was associated with a rebound of the CEA serum level, our case shows that serial measurements of serum CEA can be used for treatment planning and for assessing the patient's treatment response for this rare disease.

Fig. 1

Barium enema study showing left-anterior displacement of the posterior wall of the rectum (arrows).

Fig. 2

(A) Saggital T1-weighted MRI scan showing presacral lesion with intermediate signal intensity invading surrounding structures (arrow). (B & C) Axial T1- and T2-weighted MRI scan showing multicystic mass with intermediate signal intensity (thick arrow). The cyst shows hypointense and hyperintense signal, respectively (thin arrow).

Fig. 3

On sectioning, the mass displays a firm gray-white appearance (thick arrow) and contains several, discrete cysts (thin arrow) filled with yellow gelatinous material. The ill-defined mass impinges on the outer wall of rectum, presacral soft tissue and coccygeal bone.

Fig. 4

(A) The tumor consisits of many scattered malignant glandular components with infiltrative growth to surrounding tissue (× 100 H&E stain). (B & C) The wall of cysts are lined by benign-looking ciliated columnar (B), columnar (C) and focal cuboidal epithelium (not shown), which is consistent with TGC (× 200 H&E stain).