Case Author(s): M. Roarke , 9/1/95 . Rating: #D3, #Q4

Diagnosis: Tubulovillous adenoma of the colon hepatic flexure.

Brief history:

This patient had an annular constricting rectal Dukešs stage C carcinoma resected in September 1994. Before this resection, the patient had received a course of radiation therapy. Subsequent to the resection, the patient received chemotherapy. On a follow-up colonoscopy in April 1995, a sessile mass was noted in the ascending colon. This mass was not noted prior to the operation since colonoscopy could not be performed due to the marked stricturing the rectal carcinoma. Biopsy in April 1995 demonstrated benign histology. The patient had a repeat colonoscopy on 7-11-95, which again demonstrated the sessile mass in the region of the ascending colon/hepatic flexure. In light of the previous history of rectal carcinoma, a PET study was requested to evaluate for metastatic disease prior to resection of the hepatic flexure lesion. Biopsy of the hepatic flexure lesion on 7-11-95 again demonstrated a benign histology. Patient with a history of annular constricting rectal Dukešs stage C carcinoma resected in September 1994.

Images:

Images from whole body F-18 FDG PET study.

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Full history/Diagnosis is available below


Diagnosis: Tubulovillous adenoma of the colon hepatic flexure.

Full history:

This patient had an annular constricting rectal Dukešs stage C carcinoma resected in September 1994. Before this resection, the patient had received a course of radiation therapy. Subsequent to the resection, the patient received chemotherapy. On a follow-up colonoscopy in April 1995, a sessile mass was noted in the ascending colon. This mass was not noted prior to the operation since colonoscopy could not be performed due to the marked stricturing the rectal carcinoma. Biopsy in April 1995 demonstrated benign histology. The patient had a repeat colonoscopy on 7-11-95, which again demonstrated the sessile mass in the region of the ascending colon/hepatic flexure. In light of the previous history of rectal carcinoma, a PET study was requested to evaluate for metastatic disease prior to resection of the hepatic flexure lesion. Biopsy of the hepatic flexure lesion on 7-11-95 again demonstrated a benign histology.

Findings:

A single focus of moderately increased activity was found in the area of the previously described sessile mass in the ascending colon hepatic flexure suspicious for malignancy. At surgery, this lesion proved to be a tubulovillous adenoma with a single area of atypia.

Discussion:

As of this writing, PET imaging may not be sufficiently specific in differentiating between malignant and some benign neoplasms of the colon.

Followup:

Resection of the sessile mass in the region of the hepatic flexure/ascending colon revealed tubulovillous adenoma without evidence of malignancy.

Major teaching point(s):

Although FDG-PET is very useful in differentiating between recurrent colorectal cancer and fibrosis, it may not be specific in distinguishing malignant neoplasms of the colon from some of the benign lesions with a high metabolic rate.

ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Gasterointestinal System, Category:Neoplasm, Neoplastic-like condition)

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Case number: pt003

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