Persistent alpha-fetoprotein elevation in patients without viral hepatitis, cirrhosis, hepatocellular carcinoma: A report of six cases and literature review

Abstract

BACKGROUND

Alpha-fetoprotein (AFP) is an oncofetal protein present at high concentrations during fetal life and subsequently replaced by albumin. Serum AFP levels remain very low throughout adulthood life without malignancy, but may become elevated in individuals with pregnancy, viral hepatitis, active liver injury, cirrhosis, germ cell tumors, or hepatocellular carcinoma (HCC).

CASE SUMMARY

In this descriptive case series, we present 6 patients with mild, persistent, and stable AFP elevation in the absence of active liver injury, advanced fibrosis (or cirrhosis), or neoplasms, with a mean follow-up of 48 months in our liver clinic. None of the 6 cases had identifiable causes or a diagnosis of viral hepatitis, cirrhosis, or HCC. AFP elevation was relatively mild and stable throughout follow-up, liver function tests remained normal, and no patient developed active liver injury or malignancy, including HCC. We summarize their presentations and prognoses and review the related literature.

CONCLUSION

These six cases represent an uncommon clinical presentation of AFP elevation characterized by mild, persistent, and stable elevation in the absence of active liver injury, advanced hepatic fibrosis (or cirrhosis), and neoplasms. The prognosis in this case series was excellent: No patient had a doubling of AFP from baseline, and none developed malignancy. This descriptive case series suggests that comprehensive evaluation and regular follow-up remain necessary in this clinical scenario until larger cohort studies confirm its benign course and outcome.

Key Words: Alpha-fetoprotein; Alpha-fetoprotein elevation; Viral hepatitis; Cirrhosis; Hepatocellular carcinoma; Case report

Core Tip: This case series presents 6 cases of mild, persistent, and stable alpha-fetoprotein elevation in the absence of active liver injury, advanced hepatic fibrosis (or cirrhosis), or neoplasms, with a mean follow-up of 48 months. This is a unique and benign clinical presentation that has not been thoroughly described or previously reported.

INTRODUCTION

Alpha-fetoprotein (AFP) is an oncofetal protein actively synthesized and in high serum concentration during fetal life and subsequently replaced by albumin as the major protein[1]. Serum AFP level remains very low throughout the adult life if without active hepatocyte injury and regeneration or malignancy[2]. Serum AFP level ≤ 9 ng/mL is generally considered as a normal laboratory value for non-pregnant adults and suggests no significant elevation of the tumor marker[3]. AFP concentration may become elevated with hepatocyte injury and regeneration, such as hepatitis B flare, recovery phase after other causes of severe liver injury, and progression of liver injury to cirrhosis[4-6]. Studies have shown that AFP elevations can also be seen in patients with germ cell tumors, such as teratomas, malignancies of primitive gut origin, and hepatocellular carcinoma (HCC)[7]. Elevated serum AFP ≥ 10 ng/mL can be seen in 11%-47% patients with cirrhosis, 15%-58% patients with chronic hepatitis B[8]. AFP is an important serum biomarker for diagnosing HCC; approximately 60%-70% patients with HCC present with AFP elevation, that usually is > 200 ng/mL[9]. Yen et al[10] study demonstrated that overall 51.2% of patients with HCC had elevated AFP levels. Significant serum AFP elevation to 400 ng/mL has been one of the diagnostic criteria for HCC, and that can be seen in 28%-87% of patients with HCC[11]. In this descriptive case series, we present 6 cases of persistent, mild, and stable AFP elevation in the absence of viral hepatitis, liver injury, advanced fibrosis (or cirrhosis), or neoplasms, with a mean follow-up of 48 months. None of the patients had progressive AFP elevation or developed HCC or another malignancy. We also review the related literature in the discussion.

CASE PRESENTATION

All 6 cases were followed in our University of California Irvine (UCI) liver clinic from 2017 to 2023. Informed consent was waived per approved Institutional Review Board of UCI. Serum AFP testing was performed in our clinic laboratory using a Beckman Coulter chemiluminescent immunoassay for the quantitative determination of AFP levels in human serum. The instrument used was the Beckman Coulter UniCel DXI 800. The normal serum AFP value was ≤ 9 ng/mL[3]. In this study, mild and persistent AFP elevation was defined as an AFP level > 9 ng/mL and < 50 ng/mL on 3 occasions over an 18-month period. For patients with elevated serum AFP levels, HCC screening was performed using serum AFP testing and abdominal ultrasound every 6 months. Diagnostic criteria for HCC were defined as previously reported[10].

The data were collected retrospectively and the related clinical presentation, diagnosis, imaging and laboratory data, and months of follow-up of our 6 cases were summarized in Tables 1 and 2, and Figure 1. Briefly, the mean age was 62 (range 36-74) years-old. Three were males; 3, females. The diagnosis of underlying liver diseases for these 6 cases included metabolic dysfunction-associated steatotic liver disease (MASLD) alone (n = 1), MASLD plus liver cyst (n = 3), liver cyst alone (n = 1), AFP elevation without underlying chronic liver disease (CLD) (n = 1). None of them carried diagnosis of viral hepatitis B and C, cirrhosis, or HCC. During a mean of 48 months follow-up, they had persistently normal alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin. AFP elevation was mild, with levels ranging from 8.9 ng/mL to 29.6 ng/mL, and fluctuated slightly; however, ALT and AST levels remained within the normal range throughout follow-up, indicating no active liver injury. All 6 cases had persistent and stable AFP elevation with normal liver function tests (LFTs) and ultrasound imaging during visit follow-ups.

Figure 1 Time-course changes of serum alpha-fetoprotein in our 6 cases. The time course of follow-up by months are shown on the x-axis, “0” means initial visit. The serum alpha-fetoprotein levels at different follow-up visit are shown on the y-axis for each case. AFP: Alpha-fetoprotein.

Table 1 Basic clinical characteristics, follow-up duration, and means and ranges of serum alpha-fetoprotein elevation.

Case	Age	Sex	Past medical history	Diagnosis of underlying liver disease	Months of follow-up	Mean AFP elevation (range) ng/mL	AFP initial	AFP EOF
1	69	Female	Pancreatic cyst, stable ovarian cyst	Elevated AFP, liver cyst	54	27.3 (25.2-29.6)	29.6	25.8
2	68	Female	Breast cancer, status post lumpectomy, radiation, chemotherapy, HLD, overweight	Elevated AFP, liver cyst, MASLD	54	16.2 (14.4-18.6)	18.6	14.4
3	61	Female	Right side breast cancer, status post lumpectomy and radiation	Elevated AFP, liver cyst, MASLD	54	12.8 (11.6-14.2)	11.6	14.2
4	74	Male	Macrocytic anemia, alcohol use, hereditary hemochromatosis	Elevated AFP	36	10.7 (9.2-12.9)	9.2	10.6
5	36	Male	Mild elevated LFTs, fatty liver	Elevated AFP, MASLD, liver cyst	36	10.5 (9.7-12.9)	10.4	9.7
6	64	Male	Abnormal LFTs, fatty liver, liver cyst, obesity	Elevated AFP, MASLD	54	9.8 (8.9-11.1)	9.5	10.8

AFP: Alpha-fetoprotein; EOF: End-of-follow-up; MASLD: Metabolic dysfunction-associated steatotic liver disease; HLD: Hyperlipidemia; LFT: Liver function test.

Table 2 The actual alpha-fetoprotein and liver enzyme values during follow-up visits.

Case	AFP levels (ng/mL) at different follow-up by months										Liver function test (U/L)
	0	6	12	18	24	30	36	42	48	54	AST	ALT	ALP
1	29.6	26.3	29.6	28.7	26.3	26.8	27.2	27	25.2	25.8	13-20	8-16	57-84
2	18.6	17.3	16.7	17.5	15.3	15.4	15.8	16.3	14.9	14.4	15-31	10-48	39-55
3	11.6	11.9	13.2	11.7	11.8	12.8	12.6	13.9	14	14.2	23-34	16-34	26-43
4	9.2	11.5	12.1	10.6	10.5	10.5	10.6				22-40	17-41	61-80
5	10.4	9.9	10.6	9.9	12.9	10	9.7				15-28	10-27	54-91
6	9.5	9.7	9.4	9	8.9	10.7	9.2	9.4	11.1	10.8	17-25	15-34	37-52

AFP: Alpha-fetoprotein; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; ALP: Alkaline phosphatase.

Individual case presentation

Case 1: A 69-year-old Asian woman was followed for a liver cyst sized in 0.5 cm and chronically elevated serum AFP. During follow-up, her medications included safe brand vitamin B complex, calcium citrate and vitamin D, pancrelipase and risedronate. She had history of a liver cyst 0.5 cm in size; and single 5 mm × 4 mm pancreatic cyst in the tail of the pancreas and benign stable simple ovarian cyst sized in 2.1 cm. She also had longstanding history of AFP elevation with no evidence of HCC by multiple imaging studies or other relevant liver conditions. Her initial serum AFP level was 29.6 ng/mL, and ranged from 25.2 to 29.6 within 54 months follow-up (Figure 1, Table 1). She had normal AFP-L3 level (< 1%) for several times. She had persistently normal LFTs, with AST ranging from 13 U/L to 20 U/L, ALT from 8 U/L to 16 U/L, and ALP from 57 U/L to 84 U/L (Table 2). Her serology showed hepatitis B surface antigen (HBsAg) negative, hepatitis B surface antibody (anti-HBs) non-reactive, hepatitis B core antibody (anti-HBc total) non-reactive, and hepatitis C antibody (anti-HCV) non-reactive. She did not have hepatomegaly or splenomegaly, nor evidence of liver lesion, HCC, or cirrhosis, confirmed by multiple abdomen ultrasound studies and magnetic resonance imaging (MRI). She had several shear wave elastography (SWE) tests showing stage 0-1 hepatic fibrosis. She had stable liver cyst and pancreatic cyst confirmed by endoscopic ultrasound and MRI and stable benign ovarian cyst confirmed by transvaginal ultrasounds. Her end of follow-up (EOF) AFP level was 25.8 ng/mL.

Case 2: A 68-year-old Asian woman with persistent serum AFP elevation and a stable liver cyst sized in 1.6 cm. Her medication included ibandronate 150 mg every 30 days. She had past medical history of breast cancer, diagnosed in 2010, status post lumpectomy, radiation, and completed chemotherapy with Herceptin last dose in 02/2015, and remained in remission for 8 years, also history of hyperlipidemia (HLD), overweight managing by diet and exercise, and clinical and imaging diagnosis of MASLD. MRI showed multiple simple liver cysts with the largest measuring 1.6 cm. Her AFP level ranged from 14.4 to 18.6 within 54 months follow-up (Figure 1, Table 1). She had normal serial AFP-L3 (< 1%). She had normal LFTs, with AST ranged 15-31 U/L; ALT, 10-48 U/L; and ALP, 39-55 U/L (Table 2). Her serology showed negative HBsAg, anti-HBs anti-HBc total, and anti-HCV. She had multiple follow-up abdominal ultrasounds that showed no solid liver lesions. She did not have evidence of cirrhosis or advanced liver fibrosis confirmed by multiple SWE showing stage 0-1 hepatic fibrosis. Her initial AFP level was 18.6 ng/mL and EOF AFP level was 14.4 ng/mL.

Case 3: A 61-year-old Caucasian woman with persistent AFP elevation and a stable liver cyst 0.5 cm. Her medications included zaleplon for insomnia. She had history of right-side breast cancer, status post lumpectomy and radiation in 2004 and completed full course five years tamoxifen treatment and finished around 10/2019 and remained in remission for 4 years. She had imaging diagnosis of MASLD. Her serum AFP elevation was ranged from 11.6 to 14.2 within 54 months follow-up (Figure 1, Table 1). She did not have solid liver lesion or HCC indicated by multiple abdominal imaging and normal AFP-L3 (< 1%). She had persistently normal LFTs, with AST ranged 23-34 U/L; ALT, 16-34 U/L; and ALP, 26-43 U/L (Table 2). Her serology showed negative HBsAg, anti-HBs, anti-HBc total, and anti-HCV. Her ultrasound imaging studies reported stable liver cyst. She did not have cirrhosis or fibrosis confirmed with SWE reported stage 0-1 hepatic fibrosis. Her initial AFP level was 11.6 ng/mL and EOF AFP level was 14.2 ng/mL.

Case 4: A 74-year-old Caucasian man with persistent AFP elevation. He had history of macrocytic anemia, social alcohol use, and hereditary hemochromatosis with compound heterozygous HFE gene mutation (C282Y/H63D mutation), but he did not need phlebotomy treatment. Patient underwent bone marrow aspiration with normal bone marrow cellularity and chromosome studies. He had further reduced his occasional alcohol consumptions. His serum AFP elevation was ranged from 9.2 to 12.9 within 36 months follow-up (Figure 1, Table 1). He did not have solid liver lesion or HCC indicated by multiple abdominal imaging studies. He had normal AFP-L3 (< 1%) and LFTs, with AST ranged 22-40 U/L; ALT, 17-41 U/L; and ALP, 61-80 U/L (Table 2). His serology showed negative HBsAg, anti-HBs, anti-HBc total, and anti-HCV. He did not have cirrhosis; his SWE reported stage 2 hepatic fibrosis. His initial AFP level was 9.2 ng/mL and EOF AFP level was 10.6 ng/mL.

Case 5: A 36-year-old Caucasian man with persistent AFP elevation. He had prior history of mild elevated LFTs, liver cyst sized in 0.7 cm, and fatty liver. His initial serum AFP level was 10.4 ng/mL, and ranged from 9.7 to 12.9 within 36 months follow-up (Figure 1, Table 1). He had normal LFTs, with AST ranged 15-28 U/L; ALT, 10-27 U/L; and ALP, 54-91 U/L (Table 2). His serology showed negative HBsAg, anti-HBs, anti-HBc total, and anti-HCV. He did not have cirrhosis or fibrosis confirmed with SWE reported stage 1 hepatic fibrosis. Fatty liver diagnosed by imaging. MRI showed a 0.9 cm liver cyst. He continued follow-up with ultrasound imaging and laboratory including LFTs, AFP monitoring every 6 months. His liver cyst was stable by multiple ultrasound imaging. His EOF AFP level was 9.7 ng/mL.

Case 6: A 64-year-old Caucasian man with persistent AFP elevation. He had prior history of mild elevated LFTs, MASLD, liver cyst sized in 1.1 cm, and obesity. His initial serum AFP level was 9.5 ng/mL, and ranged from 8.9 to 11.1 within 54 months follow-up (Figure 1, Table 1). He had normal LFTs, with AST ranged 17-25 U/L; ALT, 15-34 U/L; and ALP, 37-52 U/L (Table 2). His serology showed negative HBsAg, anti-HBs, anti-HBc total, and anti-HCV. He did not have cirrhosis or fibrosis confirmed with SWE reported stage 1 hepatic fibrosis. His liver cyst was stable confirmed by ultrasound imaging studies. His EOF AFP level was 10.8 ng/mL.

DISCUSSION

Serum AFP elevation has been associated with viral hepatitis, active liver injury and regeneration, cirrhosis, and HCC[7]. To our knowledge, this is the first case series report on six cases with mild, persistent, and stable serum AFP elevation in the absence of active liver injury and regeneration, advanced fibrosis (or cirrhosis), and neoplasm for as long as of a mean 48 months follow-up.

Several case reports in the literature have described serum AFP elevation in patients with unusual diagnoses or medication use. Prabhudev et al[12] reported a case with decompensated cirrhosis, portal hypertension, and markedly elevated serum AFP level without evidence of HCC. Senturk and Cumali[13] reported three cases of extreme elevation of AFP with decompensated cirrhosis, but without HCC. Liu et al[14] reported a case of AFP elevation due to active autoimmune hepatitis. Chua et al[15] reported a case of AFP elevation due to the use of complementary health products with acute liver injury. Saracoglu et al[16] reported a case of AFP elevation (> 50000 ng/mL) due to hereditary persistence of AFP, a rare and benign inherited autosomal dominant condition. The 6 cases we presented were very different from those previously reported cases by above literature in that our cases had persistently elevated AFP levels in the absence of any identifiable causes, such as active liver injury, viral hepatitis, cirrhosis, and HCC or other malignancy during a longtime follow-up. Although our cases were diagnosed by incidental finding, it did demonstrate chronic and stable elevation of serum AFP can occur in the absence of related CLD, liver injury and regeneration, or malignancies, that carried on a very benign clinical course.

There were several cancerous and non-cancerous causes reported involving liver and other organs that lead to serum AFP elevation, such as viral hepatitis, cirrhosis, HCC, germ cell tumor, and gastric cancer[11]. There were studies that reported possible mechanisms of AFP elevation. As shown in Table 3, Caviglia et al[17] study showed that serum AFP elevation in non-HCC patients could be correlated with active liver injury or cirrhosis with liver cell regeneration. Liver fibrosis is a pathological repair of chronic liver injury, where hepatocytes are repeatedly destroyed and then regenerated. Hepatocyte destruction, regeneration, and repair may be mechanisms that lead to elevated AFP levels. Seo et al[18] study showed that elevated serum AFP level (> 10 ng/mL) may indicate liver regeneration and repair in patient with acute hepatitis A. In acute liver injury, elevated serum AFP levels often indicate active liver regeneration. Kuhlmann et al[19] study showed AFP level was elevated in the presence of steatosis, and hepatocyte regeneration. In addition, Nishida et al[20] and Goldstein et al[21] studies showed elevated AFP levels due to increased oxidative stress, cell proliferation, and alterations of hepatocellular interactions and loss of normal structural arrangements. In our case series, cases 1-3 had persistently AFP elevation up to 1.5-3 times upper limit normal (ULN), but cases 4-6 had milder persistent AFP elevation 1-1.5 times ULN. All our cases had negative HBsAg, anti-HBc total, thus, not indicated for HBV DNA test. All 6 cases did not have any active liver injury confirmed by laboratory with normal LFTs, no evidence of viral hepatitis B or C confirmed by serological tests, and no evidence of advanced fibrosis or cirrhosis confirmed by elastography with stage 0-2 fibrosis, and ultrasound imaging. Thus, our cases indicated possible other unknown causes for such benign serum AFP elevation, unidentified by our current hepatology workup, and suggested more studies are needed to investigate the possible underlying causes.

Table 3 Literature summary on possible underlying causes and mechanisms of serum alpha-fetoprotein elevation.

Authors	Summary of findings
Caviglia et al[17]	AFP levels increased significantly from advance fibrosis without HCC to the progression of HCC
Seo et al[18]	An elevated serum AFP level often indicates active liver regeneration
Kuhlmann et al[19]	An increase in AFP expression during hepatocyte regeneration
Nishida et al[20]	Serum AFP level correlated with the accumulation of oxidative DNA damage in hepatocytes
Goldstein et al[21]	Alteration in hepatocellular interactions and loss of the normal structural arrangement led to an elevated serum AFP level

AFP: Alpha-fetoprotein; HCC: Hepatocellular carcinoma.

High serum levels of AFP usually mean a high risk for HCC development and poor prognosis, up to 70% of HCC patients showed elevated serum levels of AFP[22,23]. The guidelines of the American Association for the Study of Liver Diseases and the Asian Pacific Associations for the Study of the Liver recommend AFP testing every 6 months together with ultrasound for HCC screening in high-risk patients with liver disease including those with cirrhosis, chronic hepatitis B, chronic hepatitis C with advanced fibrosis[24,25]. Su et al[26] study revealed that patients with CLD undergoing regular HCC surveillance with AFP monitoring, a high AFP level and serial AFP-increase > 10% every 3-6 months increased the risk of HCC, and regular AFP surveillance helps to detect HCC at an early stage. Our presented six cases had mild, persistent, and stable AFP elevation with the highest AFP elevation to 29.6 ng/mL, a potential risk for HCC, but none had developed HCC or other malignancies. It should also be noted AFP-L3 is another biomarker for diagnosing HCC[4,27]. In our 4 cases with AFP-L3 tests, none showed its elevation.

Studies have shown that AFP is a serum protein with an ability to bind and transfer estrogens and antiestrogens used for the breast cancer treatment[28,29]. In our case report, cases 2 and 3 had history of breast cancer and finished chemotherapy treatment, achieved and remained in remission during follow-up. As we had no data on their serum AFP level before achieving clinical remission in these 2 cases, we could not comment on the possible roles of such mild and stable AFP elevation in the prognosis of breast cancer, though it is unlikely related.

All our six patients had regular and long-term follow up as long as a mean of 48 months, and none had developed HCC or other malignancies, indicating this could be a very benign long-term outcome in these cases. That also raises another issue on how frequent and how long we should follow this unique group of patients for their mild and persistent serum AFP elevation. Additionally, although our 6 cases showed that they had a very benign clinical course and outcome, our case series could not draw a clear conclusion or provide some recommendation on how to follow-up these patients. Thus, our findings also indicated the needs of further studies to determine its frequency, long-term outcomes and underlying mechanism(s) using a large cohort with even longer follow-up.

The 6 cases we presented represent a benign course of AFP elevation when the elevation is mild, stable, and not increasing further; none of the patients developed malignancy. Our descriptive case reports suggested that the large studies are needed to confirm our findings, and the current guidelines may need to be updated to include this possible clinical presentation after further study and confirmation. More importantly, data are needed to support not to recommend further serum AFP and liver imaging for monitoring after certain period of observation.

CONCLUSION

In summary, our six cases indicated a unique clinical presentation with persistent, mild, and stable serum AFP elevation for a long period of time, that can occur in the absence of active liver injury, advanced hepatic fibrosis (or cirrhosis), or neoplasm. Although all cases in this descriptive series showed a benign clinical course and outcome, comprehensive evaluation and regular follow-up remain necessary until larger cohort studies confirm the benign course and outcome.