Anal adenocarcinoma - tumor regression grade 1

Case contributed by Jan Frank Gerstenmaier


Anal adenocarcinoma pre- and post chemoradiotherapy.

Patient Data

Age: 60 years
Gender: Female


CLINICAL NOTES: Ulcerated anal skin tag. 3/12 Hx of pain/PR bleeding -> biopsies.

MACROSCOPIC DESCRIPTION: "Unlabelled as to site":  Multiple fragments of soft tan and cream tissue 1-4mm.  A1. 


The section shows a polypoid epithelial lesion composed of tubular and villous structures lined by a stratified arrangement of pleomorphic columnar epithelial cells. These have enlarged round, oval and angulated hyperchromatic and vesicular nuclei and a small amount of eosinophilic cytoplasm. Occasional mitotic figures are identified. Irregularly shaped glandular structures are seen to extend into connective tissue at the base of the lesion. Similar irregularly shaped glandular structures are also present within the lamina propria of the larger accompanying fragment of squamous mucosa. No lymphovascular or perineurial invasion is seen. The features are of moderately differentiated adenocarcinoma arising in a severely dysplastic tubulovillous adenoma.


Anal skin:  Moderately differentiated adenocarcinoma arising in a severely dysplastic tubulovillous adenoma.

Initial staging MRI


MR Anal Cancer Staging

Multiplanar noncontrast small field of view MR imaging of the pelvis has been obtained.

An anal polypoid lesion identified, extending down from the left anal mucosa.

This measures 3.8 cm in length. Within the distal half of the anal canal, this lesion involves the mucosa at the 1-2 o'clock position, just touching the internal sphincter. The external sphincter is normal and the intersphincteric plane is preserved. The mesorectum and rectum appear normal.

There are no abnormal inguinal lymph nodes. Visible bones are unremarkable. A 1.5 centimeter uterine leiomyoma is shown. In addition, there is increased endometrial thickness at 1.4 centimeters with small cystic spaces within, is seen in previous CT.


Low anal canal lesion from the left side, probably just involving internal sphincter at the 1-2 o'clock position superficially at the level of the anal verge (T2). No external sphincter or intersphincteric fat plane involvement identified. No inguinal lymphadenopathy.

Endometrial abnormality suspicious for malignancy, requires further evaluation.


Nuclear medicine

FDG-avid anal mass. No evidence of metastases.

Staging CT pre- and post chemoradiotherapy


Pre chemoradiotherapy:

Abdomen and pelvis: No focal liver lesion. There is a 7 mm soft tissue attenuation exophytic nodule at the upper pole of the left kidney.

Spleen, adrenal glands, pancreas appear normal. No free fluid or lymphadenopathy in the abdomen or pelvis. The uterus contains a number of calcifications within the myometrium. The endometrial thickness measures at least 12 mm. There is uncomplicated sigmoid diverticulosis.

Some ill-defined soft tissue thickening is seen in the posterior anal canal, apparently extending to the anal cleft. No destructive bone lesion is identified.


1. No evidence of metastatic disease. No convincing rectal lesion, but a low anal lesion with possible extension into the natal cleft is seen.

2. Incidental subcentimeter exophytic nodule at the left kidney suspicious for a small neoplasm;

3. Endometrial thickening. Recommend pelvic ultrasound if clinically appropriate.

Post chemoradiotherapy: No evidence of metastasis.


CLINICAL NOTES: Peri-anal skin Bx - 3 o'clock. Subcutaneous anal tissue - 3 o'clock. 60 y/o F with PHx anal adenoCa treated with chemo + XRT for rebiopsy.


1. "Perianal skin 3 o'clock":  A polypoid fragment of tan tissue 10mm. Bisected.  A1.

2. "Subcutaneous tissue 3 o'clock":  A fragment of fibrous tissue 8mm.  A1.  


1. Sections show squamous mucosa with normal maturation. The lamina propria is moderately fibrotic with a chronic inflammatory infiltrate and occasional dilated vessels.  There is no evidence of dysplasia or an invasive malignancy.

2. Sections show fibrous and fatty tissue with a small amount of squamous epithelium. There is no evidence of dyplasia or of an invasive malignancy.


1. Perianal skin, 3 o'clock:  Benign squamous mucosa.

2. Subcutaneous tissue 3 o'clock: Benign fibrofatty tissue

Post chemoradiotherapy


Comparison is made with the previous examination. At the site of the previously identified anal lesion, no clearly viable residual tumor is identified. At the point of previously identified contact with the internal sphincter at the 3 o'clock position, there is a 17.7 x 2.3 x 11.6 mm lesion with no definite high T2 signal identified to suggest active tumor identified. Previously the lesion measured 25.5 x 5.9 x 20 mm. The rectum and anal sphincters appears normal.

Since previous, the endometrial thickness has normalized. 1.5 centimeter posterior loops of uterine leiomyoma is again noted.

Conclusion: Apparent excellent tumor response with significant reduction in size and no definite residual tumor signal (mrTRG 1).

Case Discussion

The majority of anal carcinomas are keratinizing or basaloid, e.g squamous cell carcinoma. Anal adenocarcinoma is rare. Associations include chronic fistula-in-ano, anal Crohn disease, and anal sexual intercourse.

See reference 1 for details of tumor regression grading.

This case contains the complete workup including initial biopsy result, staging MR, PET/CT and CT, as well as follow up biopsy result, re-stating MR and CT.

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