Isolated hilar mass mimicking cholangiocarcinoma as a rare metastatic manifestation of recurrent colorectal cancer: A case report

Abstract

BACKGROUND

Colorectal cancer remains as one of the most common cancers that are diagnosed and remains as a significant contributor to morbidity and mortality. Despite advances in techniques, improving access to diagnostic modalities and increasing awareness, it often presents at a later stage and can recur despite treatment. Recurrence can be variable and can occur years after treatment. Liver is the most common location for metastasis to occur followed by lungs. However, atypical sites of metastasis can occur although unusual and colorectal cancer can spread to the spleen, hilum of the liver, adrenals, bone, skeletal muscles, skin, prostate, brain, parotid gland, thyroid gland and even the cardiac muscle. It is crucial to recognize the metachronous nature of the metastasis and to only present at a single site as within this lies the rarity of the case. The mass itself mimicked a cholangiocarcinoma or a Klatskin’s tumor initially and only through pathology was the diagnosis established. We present an unusual case of recurrent colorectal cancer that occurred several years post treatment and presented as an isolated metastasis to the hilum of the liver leading to biliary obstruction without any other identifiable lesions including in the colon itself.

CASE SUMMARY

A 68-year-old male with history of colon cancer presented with obstructive jaundice to the hospital. After evaluation with imaging studies was diagnosed with mass at the hilum of the liver that was leading to obstruction. With percutaneous biopsies obtained by interventional radiology, the diagnosis of metastatic adenocarcinoma originating from the colon was established. He was deemed not to be a surgical candidate and is currently pursuing chemotherapy.

CONCLUSION

A metastatic adenocarcinoma of the colon that presents as a hilar mass and mimics cholangiocarcinoma is very rare. The metachronous nature along with the isolated metastasis involving the hilum of the liver makes this case unique. Diagnosis can be challenging and needs a tissue specimen along with immunostaining to achieve an accurate diagnosis and provide appropriate treatment. Biliary decompression is performed either endoscopically or percutaneously and is part of the multidisciplinary approach involving medical and surgical oncology teams.

Key Words: Colon cancer; Pathogenesis; Gastroenterology; Oncology; Endoscopy; Case report

Core Tip: Colorectal cancer is a commonly encountered malignancy and has potential to metastasize to distant organs. We present an atypical case of an isolated metastatic site that involved only the hilum of the liver and was a metachronous lesion that occurred several years after the initial diagnosis. Presentation in this manner can mimic cholangiocarcinoma and diagnosis is established through pathology.

INTRODUCTION

Colorectal cancer is the third most common cause of cancer and the second most common cause of cancer-related death worldwide[1]. Despite advances in endoscopy and attempts at improvement in access, it remains a challenging malignancy to combat. However, atypical sites of metastasis can occur although unusual and colorectal cancer can spread to the spleen, hilum of the liver, adrenals, bone, skeletal muscles, skin, prostate, brain, parotid gland, thyroid gland and even the cardiac muscle[2-7]. Although with increased awareness regarding prevention of colon cancer, it may be diagnosed at a later stage and may already be metastatic to a distant organ. It has been reported that up to 20% of all newly diagnosed colorectal cases may be metastatic at the time of presentation[8]. Once metastatic, the 5-year survival rate decreases to about 14%[9]. The most common sites of metastasis are the liver, lungs and the peritoneum[10]. The involvement of other organs can be surprising and when this occurs can pose a diagnostic dilemma. The case we present is an unusual one where the colorectal cancer recurred in the form of a metastatic process and presented as an isolated mass in the hilum of the liver without any other sites of metastatic involvement. Given the metachronous nature and the rather long latency period of several years, it is a rare presentation especially as there was only one site of isolated metastatic involvement. There was no hepatic involvement either which would have otherwise made it a more common presentation.

CASE PRESENTATION

Chief complaints

A 68-year-old male was referred from Oncology Clinic to the Emergency Department for evaluation of new onset elevation of liver chemistries.

History of present illness

A recent high-quality colonoscopy 3 months prior to the most recent hospitalization in September 2024 had revealed three diminutive tubular adenomas. These pre-cancerous growths were extremely small in size and did not show evidence of any high-grade dysplasia or other concerning features and all were resected completely. Upon presentation, he had scleral icterus, appeared frail and cachectic with vital signs remarkable for bradycardia. Abdominal exam elicited tenderness in right upper quadrant (RUQ) without any obvious palpable masses.

History of past illness

He had a remote history of invasive mucinous adenocarcinoma of rectosigmoid in 2017 (pT3pN1bM0, periregional lymph node involvement) for which he underwent adjuvant chemotherapy and rectosigmoidectomy. The chemotherapy regimen he received was XELOX for a total duration of 8 cycles. Subsequently he had done well clinically and was in remission but in 2021, he was unfortunately diagnosed with invasive mucinous adenocarcinoma of cecum/appendix (infiltrating to visceral peritoneum) with stage pT4ap N0cM0 for which he initially underwent cecal segmental colectomy and appendectomy and this was followed shortly by completion right hemicolectomy and lymphadenectomy (0/18 noted were positive). Following this, he underwent adjuvant chemotherapy with 5-FU and leucovorin which was completed in April 2022.

Personal and family history

There was no known family history of malignancy and he had never undergone genetic testing.

Physical examination

Upon presentation, he had scleral icterus, appeared frail and cachectic with vital signs remarkable for bradycardia. Abdominal exam elicited tenderness in RUQ without any obvious palpable masses.

Laboratory examinations

Labs were pertinent for normal hemoglobin and showed elevated bilirubin of 3.4 gm/dL, alkaline phosphatase of 230 U/L, alanine transaminase of 215 U/L, aspartate transaminase of 95 U/L. Acute hepatitis panel was unremarkable. Of note, liver chemistries a few months prior were normal.

Imaging examinations

Imaging with computed tomography (CT) abdomen revealed severe intrahepatic bile duct dilatation with suspected abnormality at the level of the common hepatic duct (Figure 1). The distal common bile duct was normal in caliber. Magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) showed intrahepatic biliary duct dilatation with a soft tissue lesion seen at the hilum branch point between the right and left biliary system that measured at least 2.6 cm in length (Figure 2). No focal liver lesions were noted. About 6 months prior to this scam, CT scans of the chest, abdomen and pelvis revealed only a tiny 4 mm left lung base subpleural nodule which was unchanged compared to previous scans. The nature of the biliary obstruction was intraluminal in nature and for further evaluation and biliary decompression, options were discussed as to the route for decompression. An endoscopic retrograde cholangiopancreatography (ERCP) was discussed vs options such as external drainage approach and patient opted for an external drain with interventional radiology as he feared potential complications of ERCP. Interventional radiology team placed an external biliary drain and obtained cytology samples simultaneously. The pathology results showed adenocarcinoma that favored a colorectal source of origin. Immunohistochemical studies demonstrated the tumor cells to be positive for cytokeratin (CK) 20 and caudal-type homeobox 2 (CDX2), and negative for CK7 (Figure 3).

Figure 1 Computed tomography abdomen revealed severe intrahepatic bile duct dilatation with suspected abnormality at the level of the common hepatic duct concerning for biliary obstruction. The distal common bile duct was normal in caliber.

Figure 2  Magnetic resonance imaging/magnetic resonance cholangiopancreatography. A and B: Showed intrahepatic biliary duct dilatation with a soft tissue lesion seen at the hilum branch point between the right and left biliary system causing biliary obstruction.

Figure 3 Immunohistochemical studies demonstrated the tumor cells to be positive for cytokeratin 20 and caudal-type homeobox 2, and negative for cytokeratin 7 which confirms adenocarcinoma of colorectal origin. CK: Cytokeratin; CDX2: Caudal-type homeobox 2.

A positron emission tomography-CT (PET-CT) scan was performed after discharge that revealed no definitive fluorodeoxyglucose PET/CT evidence of malignancy. There was no abnormal activity elsewhere including the bowel and prior surgical sites and no lymphadenopathy was noted (Figure 4). Mucinous implants to the hilum from colorectal malignancy could have been a possible differential in this case given the presentation. However, there was no evidence of any ascites or features of peritoneal carcinomatosis on any of the imaging studies he underwent.

Figure 4 Positron emission tomography/computed tomography revealed no definitive fluorodeoxyglucose positron emission tomography/computed tomography evidence of malignancy.

MULTIDISCIPLINARY EXPERT CONSULTATION

Medical and surgical oncology teams were consulted and he was deemed not to be a surgical candidate due to presence of circulating tumor DNA as well as overall functional status.

FINAL DIAGNOSIS

Recurrent colorectal cancer presenting as isolated liver hilar metastasis with pathology showing adenocarcinoma consistent with colorectal primary.

TREATMENT

Neoadjuvant chemotherapy was discussed with the patient and he wished to proceed with this. He received FOLFIRINOX with bevacizumab for 8 cycles and is currently undergoing treatment with mFOLFIRI.

OUTCOME AND FOLLOW-UP

Following up closely with oncology as outpatient. Periodic monitoring with labs including CEA levels as well as cross sectional imaging of the abdomen is being performed with the last MRI abdomen without any obvious lesions reported.

DISCUSSION

Colorectal cancer is a common malignancy that is encountered all across the world. Although efforts to increase awareness and colorectal screening continue to be underway, colorectal cancer is sometimes diagnosed at an advanced stage when it has already spread to other organs and sites in the body. The sites of metastasis that are usually encountered in clinical practice are the liver, lungs and the peritoneum[9]. Metastasis can occur via hematogenous spread as well as lymphatic dissemination[9]. It involves numerous factors including the biology of the tumor itself as well as the tumor microenvironment and factors such as cytokines, transcription factors among many others play a role[9]. The involvement of the biliary system as an isolated metastatic focus is rare and only few cases have been reported of this occurrence. The pathogenesis is believed to be due to varying mechanisms including hematogenous spread via arterial route, lymphatic spread[10]. Other potential modes include infiltration via peribiliary capillary system or post radio-frequency ablation of liver metastasis[10].

The diagnosis requires tissue sampling in order to differentiate from a cholangiocarcinoma. Histopathology would reveal adenocarcinoma and further testing with immunohistology would be needed to evaluate origin. In the case presented by Ofuchi et al[7], they emphasized that colorectal cancer can mimic a cholangiocarcinoma and imaging studies as well as histopathology stains may not be adequate enough to yield the correct diagnosis. The role of immunostaining is important to prevent errors in diagnosis and management of the patient[7]. In the case presented by Ofuchi et al[7], the patient underwent extensive surgery with right hemihepatectomy and bile duct resection based on the imaging findings appearing to be classic for cholangiocarcinoma. Onishi et al[11], also reveal a similar encounter where a patient presented with cholangitis and obstructive jaundice due to tumor infiltrating within the bile duct leading to occlusion and immunostains aided in the diagnosis. The patient was also noted to have a tumor in the descending colon for which resection was performed[11]. In both of these cases, there was no other hepatic involvement which is similar to our case as well. Stains such as CK7, CK20, CDX2 are utilized to aid in the diagnosis with CK7-negative, CK20-positive, CDX2-positive results pointing towards adenocarcinoma originating from the colon. In our case, there was a suspicion of initially a de novo diagnosis of cholangiocarcinoma. However further evaluation with a tissue diagnosis confirmed the diagnosis of metastatic adenocarcinoma arising from the colon. The key to arriving at the diagnosis was through the use of pathology with immunostaining and this was confirmed by second review by expert pathologists as well. In our patient, it is unclear as to how the metastasis occurred as there was no lymph node involvement on the last colon cancer that was diagnosed in 2021 and not any lymphadenopathy on the recent scans either. However, at the time of the initial diagnosis there was regional lymph node involvement and if this indeed stay dormant and manifest so many years later in the form of a recurrence, then it is unusual. There was no peritoneal involvement even though the last two colon cancers were mucinous adenocarcinomas, this one was only reported by pathologists as adenocarcinoma but did not report mucinous features. There was no evidence of ascites or peritoneal carcinomatosis on imaging. Mucinous implants can be seen in pseudomyxoma peritonei and is characterized by the presence of ascites that is ’gelatinous’ in consistency given the mucinous content[12].

Use of imaging modalities is certainly challenging including PET-CT scan. There can be limitations in the use of PET-CT as the uptake of cholangiocarcinoma is reported to be variable and challenging to determine abnormal uptake due to physiologic excretion of tracer in the normal hepatic parenchyma. The drain which was already present in the case of our patient also further complicated the evaluation in this region. PET-CT itself can have varying sensitivity for evaluating liver metastasis which can be significantly reduced for lesions < 1.5 cm[13]. PET-CT can face other challenges as well as compared to modalities such as PET-MR when evaluating the hepatobiliary system due to the high glucose metabolism of the liver, the variable activity of tumors and quality of images[13,14].

Management of the malignant biliary obstruction can also be challenging especially when due to a metastasis. Colorectal cancer can involve the liver itself and this can lead to obstruction which may not be amenable to endoscopic drainage techniques. Involvement of the pancreas or lymph nodes in the region and extra hepatic bile duct as well as even the peritoneum can contribute to biliary obstruction[15]. Biliary decompression can be performed either with extensive surgical procedures or more often with either endoscopic or interventional radiology guided routes. Percutaneous transhepatic biliary drainage can be performed by interventional radiology and is a feasible option for patients[16]. Endoscopic drainage techniques with internal stent placement via the endoscopic routes are also a reasonable option.

CONCLUSION

A metastatic adenocarcinoma of the colon that presents as a hilar mass and mimics cholangiocarcinoma is very rare. The metachronous nature along with the isolated metastasis involving the hilum of the liver makes this case unique. Diagnosis can be challenging and needs a tissue specimen along with immunostaining to achieve an accurate diagnosis and provide appropriate treatment. Biliary decompression is performed either endoscopically or percutaneously and is part of the multidisciplinary approach involving medical and surgical oncology teams.