Anal metastasis of rectal cancer-adenocarcinoma of squamous cells: a case report and literature review

Anal fistula metastasis of rectal cancer after neoadjuvant therapy: a case report

BACKGROUND

Anal metastasis of colorectal cancer is very rare and may present synchronously or metachronously, regardless of pre-existing anal diseases. We report a case of anal fistula metastasis after completion of neoadjuvant therapy for rectal cancer, followed by surgical resection of the primary tumor and metastatic lesion.

CASE PRESENTATION

A 50-year-old man was diagnosed with rectal cancer located 5 cm from the anal verge, with a clinical stage of cT3N0M0. He denied any medical or surgical history, and physical examination revealed no perianal disease. He underwent preoperative chemoradiation therapy (CRT) consisting of a tegafur/gimeracil/oteracil potassium (S-1)-based regimen with 45 Gy of radiation. After completion of CRT, computed tomography (CT) revealed the primary tumor's partial response, but a liver mass highly suggestive of metastasis was detected. This mass was later diagnosed as cavernous hemangioma 3 months after CRT initiation. He then underwent and completed six cycles of consolidation chemotherapy with a capecitabine-based regimen. Subsequent colonoscopy revealed the complete response of the primary tumor, but CT showed thickening of the edematous rectal wall. Therefore, we planned to perform low anterior resection as a radical surgery. However, he presented with persistent anal pain after the last chemotherapy, and magnetic resonance imaging revealed a high-intensity mass behind the anus, suggestive of an anal fistula. We considered the differential diagnosis of a benign anal fistula or implantation metastasis into the anal fistula. Fistulectomy was performed, and a pathological diagnosis of tubular adenocarcinoma, suggestive of implantation metastasis, was made. Thereafter, we performed laparoscopic abdominoperineal resection. Histopathological examination revealed well-differentiated adenocarcinoma, ypT2N0, with a grade 2 therapeutic effect. Subsequent immunohistochemistry of the resected anal fistula showed a CDX-2-positive, CK20-positive, CK7-negative, and GCDFP-15 negative tumor, with implantation metastasis. There was no cancer recurrence 21 months after the radical surgery.

CONCLUSIONS

This is the first report of anal fistula metastasis after neoadjuvant therapy for rectal cancer in a patient without a previous history of anal disease. If an anal fistula is suspected during or after neoadjuvant therapy, physical and radiological assessment, differential diagnosis, and surgical intervention timing for fistula must be carefully discussed.

Rectal Cancer Metastasis to the Anal Verge: An Unusual Case Presentation and Review of the Literature

Background

Anal metastasis of colorectal adenocarcinoma is very rare, represented by only a handful of case reports in the literature. Previously, reports of metastasis to this region had occurred following a history of anorectal disease, such as anal fistulae. Antecedent trauma to the area from hemorrhoidectomy, fissures, or perineal retractor injury have also been implicated.

Case Presentation

Herein we report the case of 69-year-old man without any history of anal disease presenting with a metachronous metastasis of a colorectal-type adenocarcinoma to the anal verge. He was previously treated for T1N0 rectal adenocarcinoma at the rectosigmoid junction with a low anterior resection 5 years prior, then had a T3N0 local recurrence at the colorectal anastomosis treated with neoadjuvant chemoradiation, and eventually a Hartmann's procedure 4 years later. Subsequently, on surveillance flexible sigmoidoscopy, a new tumor was identified on the perianal skin extending from the anal verge. Histopathology demonstrated colorectal-type adenocarcinoma. Flexible endoscopy identified no other residual or recurrent disease in the colon or rectal stump. The patient was treated with wide local excision and advancement flap reconstruction.

Conclusion

Isolated metastasis to the anus is an extremely rare occurrence for colorectal adenocarcinoma. There exists little evidence to inform management. One option is to treat like a locally recurrent rectal cancer with aggressive tri-modality management consisting of chemoradiation, abdominal perineal resection, and adjuvant chemotherapy. In the absence of metastatic disease, local resection and close surveillance remain an option. As always, patient factors should guide management.

Relapse of Rectal Cancer in an Anal Fistula: A Rare Case

BACKGROUND

Colorectal cancer is the second most common cause of cancer-related death worldwide. It is well-known that metasta sis to the liver and lung and local recurrences can occur. Additionally, colorectal cancer occasionally metastasizes to other sites. Only a few reports of such metastases have been published and no definitive therapeutic strategies have been proposed for them.

CASE REPORT

The case of a 77-year-old man who was diagnosed with rectal cancer is presented. Eighteen months after curative laparoscopic low anterior resection and D3 lymph node resection, an anal fistula metastasis was diagnosed by computed tomography and biopsy. After administering radiotherapy, percutaneous excision of the lesion. was performed. At 21 months from the surgery, the patient is healthy and no recurrence has been found.

CONCLUSION

Metachronous metastasis of a colorectal cancer to an anal fistula is rare. Careful investigation and optimal treatment can result in a disease-free status.

Endoluminal tumor implant of a colorectal cancer in an anal fistula detected by FISH techniques: a case report

Intraluminal shedding of tumor cells is a rare infrequent sporadic colorectal cancer (sCRC) mechanism of spreading. Less than 30 cases of sCRC metastasis into anal fistula have been reported. Here, we study a 72-year-old male with an adenocarcinoma arising in an anal fistula. Subsequent studies revealed another tumor in the rectum without distant metastatic disease; therefore, a curative-intent abdominoperineal resection was performed. The histologic study showed a moderately differentiated adenocarcinoma in both locations. No perineural or lymphovascular invasion was observed, and all the lymphatic nodes resected were negative for malignancy. Both tumors showed positive CK20 and negative CK7 immunostaining, but KRAS G12D mutation was only detected in the rectal tumor. After those conventional studies, a cytogenetic profile of both tumors was performed by interphase fluorescence in situ hybridization (iFISH) techniques. The FISH study displayed an identical genetic profile in both tumors, loss of the chromosomes 8 and 18q, and no alteration in chromosome 7 and 13q. Based on pathological and genetic findings, we established the same clonal origin of both tumors. Currently, the diagnosis of an intraluminal CRC metastasis relies on histologic and immunohistochemistry findings. We suggest that genetic studies at the individual cell level by FISH techniques may be useful in order to differentiate synchronous from intraluminal metastasis.

Implantation of rectosigmoid cancer in a preexisting anal fissure

Colorectal cancer (CRC) rarely spreads by implantation. We report a case of implantation of rectosigmoid cancer in an anal fissure. A 70-year-old woman with a 15-year medical history of anal fissure was referred to our hospital with anal pain of 3-month duration. Colonoscopy revealed a rectosigmoid tumor and a 10-mm submucosal tumor at the anal verge. Biopsy of the rectosigmoid and anal tumors revealed that both were moderately differentiated adenocarcinomas, and abdominoperineal resection (APR) was performed. The anal adenocarcinoma was surrounded by squamous cell epithelium and mainly proliferated in the submucosal and muscular layers. The patient was diagnosed as having rectosigmoid cancer with implantation of cancer in a preexisting anal fissure. The patient remains well 43 months post-surgery with no sign of recurrence. Implantation of CRC in anal fissure is a rare occurrence. Nevertheless, performing adequate anal examination of patients with CRC before surgery and during follow-up is necessary. Further, it is important to perform preoperative large bowel examination of patients with benign anal diseases to prevent implantation of CRC.