Tubulovillous adenoma of the rectum

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Right sided abdominal pain. Incidental finding.

Patient Data

Age: 50 years
Gender: Male

The appendix is distended and its wall edematous. There is a large amount of surrounding fat stranding and multiple right iliac fossa lymph nodes. 

There appears to be a 4 cm diameter enhancing soft tissue mass within the lumen of the rectum without obstruction, but what appears to be a vascular core. 

Small bilateral renal cysts are noted. A 4 mm calcific focus within the lower pole of the left kidney most likely represents a renal calculus. The liver, gallbladder, spleen, pancreas and adrenals are unremarkable. Incidental note is made of a splenunculus

The patient went on to have a scope at the time of appendectomy which confirmed the presence of a rectal mass. 

Appendix

MACROSCOPIC DESCRIPTION

An appendix 60 x 8 mm with attached mesoappendix 7 mm wide. Lumen filled with blood tinged fluid and wall thickness up to 4 mm. Serosa shows fibrin exudate. 

MICROSCOPIC DESCRIPTION

Sections show appendix with mucosal ulceration and transmural infiltration by acute inflammatory cells with focal necrosis of the muscularis layer.  No evidence of tumor is seen.

FINAL DIAGNOSIS: Gangrenous appendicitis.

A number of weeks later the patient went on to have a rectal resection. 

Rectal polyp

MACROSCOPIC DESCRIPTION

A mucosal resection with three orienting a long indicating proximal, a single indicating right distal and a double indicating left distal.  The specimen measures proximal to distal 50 mm, left to right 45 mm. The mucosa contains a villous polypoid mass involving the entire surface. Right side inked green, left side inked blue. The tumor appears to extend to the proximal and distal resection margins.

MICROSCOPIC DESCRIPTION

Sections show colonic mucosa, submucosa and a small amount of muscularis propria, in which a tubulovillous adenoma is seen. The tumor comprises complex tubules and villous structures lined by columnar cells with reduced cytoplasmic mucin. The nuclei are stratified, with coarse chromatin. Some nuclei are vesicular with prominent nucleoli. Mitoses are seen close to the luminal surface. The muscularis mucosae is intact and there is no evidence of malignancy. The tumor appears completely excised in the planes of sections.

FINAL DIAGNOSIS

Tubulovillous adenoma with up to high grade dysplasia.

Case Discussion

Typical appearances of a large tubulovillous adenoma of the rectum. 

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