Primary Rectal Tumor With Extensive Choriocarcinoma Differentiation in a Woman With Lung, Liver and Disseminated Peritoneal Disease: A Primary Rectal Adenocarcinoma With Extensive Choriocarcinoma Differentiation or Primary Rectal Choriocarcinoma?

Primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation is a rare neoplasm, with only sporadic cases reported worldwide. The prognosis is typically poor, and no standard therapy has been established for this tumor. We report a case of a 63-year-old woman who presented with lower abdominal and pelvic discomfort, as well as rectal bleeding. Endoscopy revealed a rectal tumor. She was diagnosed with primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation, accompanied by liver metastasis and peritoneal carcinomatosis. The immunohistochemical profile demonstrated strong and diffuse positivity for keratin (AE1/AE3), beta-human chorionic gonadotropin (β-HCG), p53, MYC, p16, and Ki-67. Molecular analysis indicated mutations in KRAS, TP53, and PI3KCA. Despite the tumor's profile, the serum β-HCG level was not elevated. A chemotherapy regimen for metastatic colorectal adenocarcinoma was initiated, but there was a poor response, with rapid tumor progression. The patient survived for only 5 months postdiagnosis. We discuss the histopathological, immunohistochemical, and molecular findings, emphasizing their relevance to the differential diagnosis of neoplasms with choriocarcinomatous differentiation.

Histologic transformation of rectal adenocarcinoma to choriocarcinoma after surgery and chemotherapy: A rare case report and review of the literature

INTRODUCTION AND IMPORTANCE

Choriocarcinoma is a rapidly progressive, widely metastatic, β-human chorionic gonadotropin (β-hCG)-secreting malignant tumor originating from trophoblast cells. Most choriocarcinomas are pregnancy-related. Choriocarcinoma of nonpregnant origin is very rare.

CASE PRESENTATION

A 60-year-old woman underwent abdominopelvic resection (APR) for low rectal cancer in May 2020. Postoperative pathological findings showed a poorly differentiated adenocarcinoma. Because of a post-operative recurrence, then she underwent chemotherapy for rectal adenocarcinoma. In February 2021, imaging finding showed metastases in her liver, both lungs and pelvis. Surprisingly, the β-hCG level was significantly elevated. A transvaginal pelvic tumor biopsy was performed and the pathology report was presented after discussions: choriocarcinoma differentiated carcinoma was considered, with no adenocarcinoma component detected. Then the patient underwent chemotherapy regimens for choriocarcinoma, which were initially effective but quickly became resistant. The patient died 8 months after the diagnosis of adenocarcinoma of the rectum transformed into choriocarcinoma.

CLINICAL DISCUSSION

The dedifferentiation of adenocarcinoma to choriocarcinoma is rarely diagnosed and the disease is often overlooked, leading to delays in diagnosis and treatment, documenting cases and their clinical outcomes is important for future research and to improve patient prognosis. Perhaps genomic assessment using next-generation sequencing (NGS) technology could help in diagnosis and guide therapeutic strategies.

CONCLUSION

We report a very rare case of non-pregnant choriocarcinoma transformed from primary rectal adenocarcinoma. Awareness of secondary biopsies in special cases and genetic testing based on the dynamics of the disease should be raised in clinical practice to better develop precise treatment plans.

Primary colon adenocarcinoma with choriocarcinoma differentiation: a case report and review of the literature

Background

Choriocarcinoma is an aggressive malignancy of trophoblastic tissue, typically of gestational etiology. Sporadic, nongestational cases are rarely found outside of the gonads. There are only 31 cases of primary choriocarcinoma of the colon reported in the literature. As a consequence of their rarity and aggressive nature, timely diagnosis and effective treatment have proved challenging, and prognosis is very poor. For that reason, we present a rare case with prolonged survival in the youngest reported patient .

Case presentation

A 26-year-old Caucasian woman presented with abdominal cramping and rectal and vaginal bleeding. Elevated serum human chorionic gonadotropin and an 8-cm right-sided mass seen on ultrasound suggested ectopic pregnancy. The patient was treated with methotrexate; however, her symptoms persisted, and her human chorionic gonadotropin levels continued to rise. Further workup showed a large mass of the sigmoid colon with multiple hepatic lesions suggestive of metastases. Preliminary pathology showed adenocarcinoma. Despite surgical resection and initiation of FOLFOX chemotherapy (folinic acid, fluorouracil, oxaliplatin), the patient had significant clinical deterioration, and her human chorionic gonadotropin increased exponentially. Further pathological review showed two distinct phenotypes: adenocarcinoma merging with choriocarcinoma. The result of evaluation of the metastatic lesions was also positive for choriocarcinoma. Treatment was promptly changed to a choriocarcinoma-targeting chemotherapy regimen of EMA/CO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine), resulting in rapid and dramatic response. The patient had mild progression after 1 year and was switched back to FOLFOX with bevacizumab. After five cycles, scans showed further progression, and the patient was started on third-line therapy with FOLFIRI (folinic acid, fluorouracil, irinotecan) and bevacizumab. Eighteen months after her diagnosis, the patient was alive and maintaining an overall response.

Conclusions

Our patient achieved a marked response and prolonged survival. Although a comprehensive review of the literature showed that survival with these tumors has improved over the past 10 years, prognosis remains poor. Currently, there is no established algorithm for the management of these rare tumors, but both the literature and our patient’s case indicate that a choriocarcinoma-targeted regimen is critical for survival. Further evaluation of these rare tumors is warranted in order to identify pathological patterns that may help in the diagnosis, management, and survival of these malignancies.