Diagnostic Approaches to Neuroendocrine Neoplasms of Unknown Primary Site

A Neuroendocrine Tumor of Unknown Primary Origin: A Case Report and Review of the Literature

Neuroendocrine tumors (NETs) are uncommon malignancies that develop from neuroendocrine cells which most commonly occur in the GI tract, lung, and pancreas. Treatment courses for these tumors are largely dictated by the primary origin site, which can present diagnostic and therapeutic challenges in NETs of unknown primary origin. Herein, we present a case of an NET of unknown primary origin with significant liver metastases. Our aim is to highlight the key components of the workup of NETs of unknown primary origin and detail the biochemical, histopathological, and imaging modalities as recommended by current literature. We highlight the importance of a multidisciplinary approach to both diagnosis and treatment of these patients as well as touch upon therapeutic options.

Recent advances and future challenges in the diagnosis of neuroendocrine neoplasms

Neuroendocrine neoplasms (NEN) are a heterogeneous group of malignancies with increasing incidence, whose diagnosis is usually delayed, negatively impacting on patients' prognosis. The latest advances in pathological classifications, biomarker identification and imaging techniques may provide early detection, leading to personalized treatment strategies. In this narrative review the recent developments in diagnosis of NEN are discussed including progresses in pathological classifications, biomarker and imaging. Furthermore, the challenges that lie ahead are investigated. By discussing the limitations of current approaches and addressing potential roadblocks, we hope to guide future research directions in this field. This article is proposed as a valuable resource for clinicians and researchers involved in the management of NEN. Update of pathological classifications and the availability of standardized templates in pathology and radiology represent a substantially improvement in diagnosis and communication among clinicians. Additional immunohistochemistry markers may now enrich pathological classifications, as well as miRNA profiling. New and multi-analytical circulating biomarkers, as liquid biopsy and NETest, are being proposed for diagnosis but their validation and availability should be improved. Radiological imaging strives for precise, non-invasive and less harmful technique to improve safety and quality of life in NEN patient. Nuclear medicine may benefit of somatostatin receptors' antagonists and membrane receptor analogues. Diagnosis in NEN still represents a challenge due to their complex biology and variable presentation. Further advancements are necessary to obtain early and minimally invasive diagnosis to improve patients' outcomes.

Emerging Treatment Options for Neuroendocrine Neoplasms of Unknown Primary Origin: Current Evidence and Future Perspectives

Among neuroendocrine neoplasms (NENs), a non-negligible proportion (9-22%) is represented by sufferers of NENs of unknown primary origin (UPO), a poor prognostic group with largely unmet clinical needs. In the absence of standard therapeutic algorithms, current guidelines suggest that the treatment of UPO-NENs should be based on tumor clinical-pathological characteristics, disease burden, and patient conditions. Chemotherapy represents the backbone for the treatment of high-grade poorly differentiated UPO-NENs, usually providing deep but short-lasting responses. Conversely, the spectrum of available systemic therapy options for well-differentiated UPO-NENs may range from somatostatin analogs in indolent low-grade tumors, to peptide receptor radioligand therapy, tyrosine kinase inhibitors (TKIs), or chemotherapy for more aggressive tumors or in case of high disease burden. In recent years, molecular profiling has provided deep insights into the molecular landscape of UPO-NENs, with both diagnostic and therapeutic implications. Although preliminary, interesting activity data have been provided about upfront chemoimmunotherapy, the use of immune checkpoint inhibitors (ICIs), and the combination of ICIs plus TKIs in this setting. Here, we review the literature from the last 30 years to examine the available evidence about the treatment of UPO-NENs, with a particular focus on future perspectives, including the expanding scenario of targeted agents in this setting.

Hypercalcemia and Bone Metastasis in a Case of Large Cell Neuroendocrine Carcinoma With Unknown Primary

Large cell neuroendocrine carcinoma (LCNEC) constitutes a rare subset of highly undifferentiated malignancies known for their aggressive nature. Although these tumors commonly originate in the lungs and gastrointestinal tract, their potential occurrence is not restricted to specific anatomical sites, giving rise to a variety of symptoms. Notably, cases of neuroendocrine tumors (NETs) with an unidentified primary source exhibit a graver prognosis and shorter survival periods compared to those with clearly identified origins. NETs frequently demonstrate a propensity to metastasize, spreading to diverse anatomical regions such as the liver, lungs, lymph nodes, and bones, illustrating their aggressive nature and the complexity of their management. In this context, we present the case of a 59-year-old male who sought medical attention in the emergency department due to right upper quadrant (RUQ) abdominal pain. Initial diagnostic assessments revealed significantly elevated liver function tests and severe hypercalcemia. A right upper quadrant ultrasound (RUQ US) was subsequently performed, which revealed heterogeneous hepatic echotexture with innumerable echogenic masses, suggesting a metastatic process. A computed tomography (CT) scan was then ordered to evaluate further the RUQ US findings, which showed numerous hypovascular liver masses, raising concerns of malignancy. A liver biopsy confirmed a diagnosis of LCNEC with an unidentified primary source.

Neuroendocrine tumour of the lesser omentum

A man in his early 20s presented to us in the outpatient department with a history of diarrhoea for 4 months. Investigations revealed elevated serum chromogranin levels and an intensely avid lesion in the gastrohepatic ligament in Gallium DOTATATE positron emission tomography (PET). The tumour was excised laparoscopically, and no other lesions were seen. The patient improved clinically and had a normal serum chromogranin level postoperatively. He is currently much improved at the 1year follow-up. We did an extensive workup to look for a primary tumour. It was concluded that it was a de novo tumour arising from the lesser sac. The recommended investigations in case of neuroendocrine tumour (NET) with unknown primary include blood investigations to look for the functional status of the tumour, histopathological examination, including immunohistochemistry, and radiological imaging, which must include a Gallium DOTATATE PET. An isolated NET of the lesser sac has not been reported in the literature.

Prioritization of Fluorescence In Situ Hybridization (FISH) Probes for Differentiating Primary Sites of Neuroendocrine Tumors with Machine Learning

Determining neuroendocrine tumor (NET) primary sites is pivotal for patient care as pancreatic NETs (pNETs) and small bowel NETs (sbNETs) have distinct treatment approaches. The diagnostic power and prioritization of fluorescence in situ hybridization (FISH) assay biomarkers for establishing primary sites has not been thoroughly investigated using machine learning (ML) techniques. We trained ML models on FISH assay metrics from 85 sbNET and 59 pNET samples for primary site prediction. Exploring multiple methods for imputing missing data, the impute-by-median dataset coupled with a support vector machine model achieved the highest classification accuracy of 93.1% on a held-out test set, with the top importance variables originating from the ERBB2 FISH probe. Due to the greater interpretability of decision tree (DT) models, we fit DT models to ten dataset splits, achieving optimal performance with k-nearest neighbor (KNN) imputed data and a transformation to single categorical biomarker probe variables, with a mean accuracy of 81.4%, on held-out test sets. ERBB2 and MET variables ranked as top-performing features in 9 of 10 DT models and the full dataset model. These findings offer probabilistic guidance for FISH testing, emphasizing the prioritization of the ERBB2, SMAD4, and CDKN2A FISH probes in diagnosing NET primary sites.

Utility of histopathological revision in the management of gastro-entero-pancreatic neuroendocrine neoplasia

BACKGROUND

Histological evaluation and grading assessment are key points in the diagnostic work-up of gastroentero-pancreatic neuroendocrine neoplasms (GEP-NENs).

AIM

To analyze the impact of histopathological revision on the clinical management of patients with GEP-NEN.

MATERIALS AND METHODS

Patients referred to our Center of Excellence between 2015 and 2021 were included in this study. Immunohistochemical slides at the time of initial diagnosis were reviewed to assess tumor morphology, diagnostic immunohistochemistry, and Ki67.

RESULTS

101 patients were evaluated, with 65 (64.4%) gastrointestinal, 25 (24.7%) pancreatic, and 11 (10.9%) occult neoplastic lesions suspected to be of GEP origin. The main changes resulting from the revision were: first Ki-67 assessment in 15.8% of patients, Ki-67 change in 59.2% of patients and grading modification in 23.5% of patients. An additional immunohistochemical evaluation was performed in 78 (77.2%) patients, leading to a confirmation of GEP origin in 10 of 11 (90.9%) of unknown primary site neoplastic lesions and an exclusion of NEN diagnosis in 2 (2%) patients. After histopathological revision, a significant modification in clinical management was proposed in 42 (41.6%) patients.

CONCLUSIONS

Histopathological revision in a referral NEN center is strongly advised in newly diagnosed GEP-NENs to properly plan prognostic stratification and therapeutic choice.

Application of Machine Learning in Predicting Hepatic Metastasis or Primary Site in Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) account for 80% of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). GEP-NETs are well-differentiated tumors, highly heterogeneous in biology and origin, and are often diagnosed at the metastatic stage. Diagnosis is commonly through clinical symptoms, histopathology, and PET-CT imaging, while molecular markers for metastasis and the primary site are unknown. Here, we report the identification of multi-gene signatures for hepatic metastasis and primary sites through analyses on RNA-SEQ datasets of pancreatic and small intestinal NETs tissue samples. Relevant gene features, identified from the normalized RNA-SEQ data using the mRMRe algorithm, were used to develop seven Machine Learning models (LDA, RF, CART, k-NN, SVM, XGBOOST, GBM). Two multi-gene random forest (RF) models classified primary and metastatic samples with 100% accuracy in training and test cohorts and >90% accuracy in an independent validation cohort. Similarly, three multi-gene RF models identified the pancreas or small intestine as the primary site with 100% accuracy in training and test cohorts, and >95% accuracy in an independent cohort. Multi-label models for concurrent prediction of hepatic metastasis and primary site returned >98.42% and >87.42% accuracies on training and test cohorts, respectively. A robust molecular signature to predict liver metastasis or the primary site for GEP-NETs is reported for the first time and could complement the clinical management of GEP-NETs.

Neuroendocrine carcinoma of tonsil presented with axillary lymph node metastasis: Management dilemma

ABSTRACT

High-grade neuroendocrine carcinoma (NEC) of the tonsil is rare and has a poor prognosis. The usual presentation is a neck mass with locoregional cervical lymphadenopathy. An axillary lymphadenopathy as a primary presentation of NEC of the tonsils is uncommon and challenging to treat. Tonsil neuroendocrine tumors display aggressive behaviors associated with early recurrence and metastasis after surgical resection. Managing this condition is demanding compared to NECs of gastrointestinal origin since, to date, the management of head-and-neck neuroendocrine tumors is still not well established. We present a 49-year-old female with a rare case of NEC of the tonsil presenting primarily with axillary lymph nodes metastasis. The patient's axillary lymph node was biopsied and revealed a Grade III neuroendocrine tumor. A positron emission tomography (PET) scan was done in searching of a primary lesion and showed a highly metabolic mass of the left tonsil as well as a left axillary lymph node suggestive of metastasis. The patient has been managed with a multimodality approach, with a combination of chemotherapy regimen and surgical resection of the axillary lymph node. Subsequent PET scan evaluation showed a complete response of the primary tumor with residual left axillary lymph node metastasis. NECs of tonsil presented with axillary lymph nodes metastasis is rare and has a poor prognostic outcome. It poses a dilemma with regard to management, as surgical resection of the metastasis is not promising given the possibility of early recurrence.

Surgical debulking is associated with improved survival for patients with neuroendocrine liver metastases of unknown primary

BACKGROUND

Resection of neuroendocrine tumors (NET) with surgical debulking of liver metastasis (NETLM) is associated with improved survival. In patients with an unknown primary (UP-NETLM), the effects of debulking remains unclear.

METHODS

The National Cancer Database (2004-2016) was queried for patients with small intestine (SI) and pancreas (P) NETLMs. If the liver was listed as the primary site, the patient's disease was classified as UP-NETLM.

RESULTS

Patients with UP-NETLM, SI-NETLM, and P-NETLM who were managed non-operatively demonstrated a significant difference in 5-year overall survival (OS) (21.5% vs. 39.2% vs. 17.1%; p < 0.0001). OS in patients who underwent debulking was higher (63.7% vs. 73.2% vs. 54.2%). Patients with UP-NETLMs who underwent debulking had similar OS to patient with SI-NETLM (p = 0.051), but significantly higher OS, depending on tumor differentiation, compared to patients with P-NETLMs. If well-differentiated, surgery for UP-NETLMs was associated with a higher rate of OS (p = 0.009), while no difference was observed if moderately (p = 0.209) or poorly/undifferentiated (p = 0.633). P-NETLMs were associated with worse OS (p < 0.001) on multivariate analysis.

DISCUSSION

Debulking in patients with UP-NETLMs was associated with similar OS compared to patients with SI-NETLMs and better or similar OS compared to patient with P-NETLMs.

An Overview of Circulating Biomarkers in Neuroendocrine Neoplasms: A Clinical Guide

Neuroendocrine neoplasms (NENs) are a heterogeneous group of diseases that are characterized by different behavior and clinical manifestations. The diagnosis and management of this group of tumors are challenging due to tumor complexity and lack of precise and widely validated biomarkers. Indeed, the current circulating mono-analyte biomarkers (such as chromogranin A) are ineffective in describing such complex tumors due to their poor sensitivity and specificity. In contrast, multi-analytical circulating biomarkers (including NETest) are emerging as more effective tools to determine the real-time profile of the disease, both in terms of accurate diagnosis and effective treatment. In this review, we will analyze the capabilities and limitations of different circulating biomarkers focusing on three relevant questions: (1) accurate and early diagnosis; (2) monitoring of disease progression and response to therapy; and (3) detection of early relapse.

Diagnostic Approaches for Neuroendocrine Neoplasms of Unknown Primary (NEN-UPs) and Their Prognostic Relevance-A Retrospective, Long-Term Single-Center Experience

Neuroendocrine neoplasms (NENs) represent a rare and heterogenous group of tumors with predominantly gastroenteropancreatic or pulmonary origin. Despite numerous diagnostic efforts, the primary tumor site remains unknown in up to 20% of the patients diagnosed with NEN. In this subgroup of NEN patients, a standard diagnostic algorithm has not yet been integrated into clinical routine. Of note, an undetermined primary tumor site in NENs is associated with an impaired clinical outcome by at least "formally" limiting treatment options exclusively approved for NENs of a certain histological origin. In this retrospective study, a patient cohort of 113 patients initially diagnosed with NEN of unknown primary (NEN-UP) was analyzed. In 13 patients (11.5%) a primary tumor site could be identified subsequently, amongst others, by performing somatostatin receptor (SSTR)-PET-based imaging, which was irrespective of the initial clinical or demographic features. Diagnostic work-up and therapeutic regimens did not differ significantly between patients with an identified or unidentified primary tumor site; only a detailed immunohistochemical assessment providing additional information on the tumor origin proved to be significantly associated with the detection of a primary tumor site. Our study revealed that a profound diagnostic work-up, particularly including SSTR-PET-based imaging, leads to additional treatment options, finally resulting in significantly improved clinical outcomes for patients with NEN-UPs.

Multidisciplinary Approach to the Diagnosis of Occult Primary Neuroendocrine Neoplasm: A Clinical Challenge

Approximately 11% to 14% of subjects with neuroendocrine neoplasms (NENs) have metastatic lesions with unknown primary origin (UPO), with the majority of UPO-NENs found in the small bowel. Herein, we assessed the available literature on UPO-NENs, focusing on clinical presentation and diagnostic techniques to identify the primary site. The identification of the primary tumor is important as it affects the prognosis; however, the clinical presentation can be non-specific in non-functioning forms. In the presence of metastatic disease, the histological sample is fundamental to obtain immunohistochemical markers that might orientate the clinician in the search for the primary tumor through radiology, functional imaging and endoscopic techniques. In summary, multidisciplinary management plays a key role in UPO-NENs, even more than in other NENs. Molecular biology and gene-expression profiling represent areas of great interest which might be developed in the near future for both the diagnosis and the treatment of these neoplasms.

Cystic hepatic metastases in treatment naïve neuroendocrine tumor: Cytomorphology clubbed with cell block immunocytochemistry clinches the diagnosis

Cystic hepatic lesions encompass a vast spectrum of infectious, non-neoplastic, and neoplastic entities. Most hepatic cysts are benign and asymptomatic, requiring no active intervention. However, symptomatic and malignant cysts need proper evaluation and specific treatment. An accurate preoperative diagnosis is pivotal for patient management. At times, these lesions may mimic, especially symptomatology and radiology, leading to a diagnostic ordeal. We herein present a case of a patient with cystic liver lesions in a treatment naïve neuroendocrine tumor that was a diagnostic dilemma on radiology. Low cellularity of cytology smears made the diagnosis challenging, and cell block immunocytochemistry finally clinched the diagnosis. A timely diagnosis provided on cytology fuelled further work-up, the discovery of primary tumor, and initiation of appropriate therapy.

EMT Molecular Signatures of Pancreatic Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms occurring predominantly in the gastrointestinal tract and pancreas. Their heterogeneity poses challenges for diagnosis and treatment. There is a paucity of markers for characterisation of NEN tumours. For routine diagnosis, immunohistochemistry of the NEN-specific markers CgA and synaptophysin and the proliferation marker Ki-67 are used. These parameters, however, are qualitative and lack the capacity to fully define the tumour phenotype. Molecules of epithelial–mesenchymal transition (EMT) are potential candidates for improved tumour characterisation. Using qRT-PCR, we measured mRNA levels of 27 tumour markers, including 25 EMT-associated markers, in tumour tissue and matched non-tumour tissues for 13 patients with pancreatic NENs. Tissue from patients with three different grades of tumour had distinctly different mRNA profiles. Of the 25 EMT-associated markers analysed, 17 were higher in G3 tissue relative to matched non-tumour tissue, including CD14, CD24, CD31, CD44, CD45, CD56, CK6, CK7, CK13, CK20, NSE, CDX2, CgA, DAXX, PCNA, laminin and Ki-67. The differences in levels of seven EMT-associated markers, Ki-67, DAXX, CD24, CD44, vimentin, laminin and PDX1 plus CgA and NSE (neuroendocrine markers) enabled a distinct molecular signature for each tumour grade to be generated. EMT molecules differentially expressed in three tumour grades have potential for use in tumour stratification and prognostication and as therapeutic targets for treatment of neuroendocrine cancers, following validation with additional samples.

Early Detection of Relapse by ctDNA Sequencing in a Patient with Metastatic Thymic Tumor and MEN1 Mosaicism

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease caused by inactivating mutations in the MEN1 gene. In the literature, few cases of MEN1 have been reported because of mosaic MEN1 mutations.

OBJECTIVE

We performed an extensive molecular characterization in several lesions and blood samples, including plasmatic circulating cell-free DNA (ccfDNA) in an exceptional case of a patient with MEN1 mosaicism causing primary hyperparathyroidism, multiple pancreatic neuroendocrine tumors (NETs), and a metastatic thymic NET.

METHODS

Blood, ccfDNA and multiple tissue analysis were performed by next-generation sequencing.

RESULTS

MEN1 mosaicism was confirmed by multiple tissue analysis. Somatic analysis of the largest pancreatic NET revealed the same MEN1 second-hit mutation as found in the thymic lesion, demonstrating its metastatic origin from the thymic lesion. Moreover, in ccfDNA we found the mosaic MEN1 mutation but also the somatic second-hit mutation found in the thymic primary tumor, revealing the presence of circulating tumor DNA (ctDNA). After surgical removal of the pancreatic metastasis, the mutated fraction of both mutations decreased, before increasing again several weeks before a new clinical relapse, suggesting that thymic ctDNA may be used as an early tumor biomarker.

CONCLUSION

This exceptional MEN1 case highlighted (1) the importance of looking for MEN1 mosaicism, (2) that MEN1 mosaicism can cause very aggressive disease, and (3) the interest in analyzing ccfDNA for confirming MEN1 mosaicism but also as a potential tumor biomarker for NET.

Lanreotide Depot to Treat Gastroenteropancreatic Neuroendocrine Tumors in a US Community Oncology Setting: A Prospective, Observational Study

INTRODUCTION

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) can result in symptoms such as diarrhea, flushing, abdominal pain, and fatigue and are often associated with a significant disease burden and poor prognosis. This non-interventional, prospective, observational study evaluated the real-world safety and effectiveness of lanreotide depot, a somatostatin analog (SSA) used to treat GEP-NETs, in a community setting.

METHODS

In this prospective, non-interventional study (NCT02730104), adult patients with locally advanced (inoperable), metastatic GEP-NETs treated with lanreotide depot were evaluated by their physician every 6 months from enrollment for 24 months. Clinically defined time to disease progression (TTDP) and overall survival (OS) were estimated for the total population and by primary tumor type (gastrointestinal [GI], pancreatic, unknown origin), and an exploratory analysis determined the rate of progression-free survival (PFS) at 12 and 24 months. Patient satisfaction was evaluated via the Treatment Satisfaction Questionnaire for Medication (TSQM-9), and safety information was recorded.

RESULTS

Of 99 patients, the 24-month PFS rate was 73.7% (95% confidence interval [CI] 63.1-81.7) and 24-month OS rate was 84.2% (95% CI 74.0-90.7). Median TTDP was not reached because few patients experienced disease progression during the study period. The majority of responding patients expressed satisfaction with treatment on each domain of the TSQM-9. Treatment-related adverse events (AEs) occurred in 19.2% of patients, while no serious AEs (SAEs) were related to the study drug.

CONCLUSIONS

Lanreotide depot is an effective and well-tolerated treatment for GEP-NETs in the real-world community setting.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02730104.

Metastatic Neuroendocrine Neoplasms of Unknown Primary: Clues from Pathology Workup

Simple Summary

While most neuroendocrine neoplasms are indolent and slow-growing tumors, subsets of cases will spread beyond the tissue of origin. Given the rather slow progress, some lesions are incidentally discovered as metastatic deposits rather than primary masses. In these cases, a biopsy is often taken to allow the pathologist to identify the tumor type and possibly the primary tumor site via microscopic examination. In this review, the authors present a simplified guide on how to approach metastatic neuroendocrine tumors from a pathologist’s perspective.

Abstract

Neuroendocrine neoplasms (NENs) are diverse tumors arising in various anatomical locations and may therefore cause a variety of symptoms leading to their discovery. However, there are instances in which a NEN first presents clinically as a metastatic deposit, while the associated primary tumor is not easily identified using conventional imaging techniques because of small primary tumor sizes. In this setting (which is referred to as a “NEN of unknown primary”; NEN-UP), a tissue biopsy is often procured to allow the surgical pathologist to diagnose the metastatic lesion. If indeed a metastatic NEN-UP is found, several clues can be obtained from morphological assessment and immunohistochemical staining patterns that individually or in concert may help identify the primary tumor site. Herein, histological and auxiliary analyses of value in this context are discussed in order to aid the pathologist when encountering these lesions in clinical practice.

The Role of Conventionally Fractionated Radiotherapy and Stereotactic Radiotherapy in the Treatment of Carcinoid Tumors and Large-Cell Neuroendocrine Cancer of the Lung

The occurrence of neuroendocrine tumors among the diagnosed neoplasms is extremely rare and is associated with difficulties in undertaking effective therapy due to the histopathological differentiation of individual subtypes and the scarce clinical data and recommendations found in the literature. The choice of treatment largely depends not only on its type, but also on the location and production of excess hormones by the tumor itself. Common therapeutic approaches include surgical removal of the tumor, the use of chemotherapy, targeted drug therapy, peptide receptor radionuclide therapy, and the use of radiation therapy. This article reviews the current knowledge on the classification and application of radiotherapy in the treatment of lung NETs. Case reports were presented in which treatment with conventional radiotherapy, radical and palliative radiochemotherapy, as well as stereotactic fractionated radiotherapy in the treatment of typical (TC) and atypical (AT) lung carcinoids and large cell neuroendocrine carcinoma (LCNC) were used. We hope that the solutions presented in the literature will allow many radiation oncologists to make the best, often personalized decisions about the therapeutic qualifications of patients.

Cystic Hepatic Neuroendocrine Tumor: A Rare Entity

ABSTRACT

A 70-year-old man presented with unspecific abdominal symptoms and weight loss was referred for a sonographic examination. Sonography revealed 3 cystic hepatic masses in an otherwise unremarkable liver. Contrast-enhanced MRI of the liver was performed to characterize the hepatic lesions and elucidate their etiology. The differential diagnosis was primarily parasitic disease or metastases with cystic transformations. 68Ga-DOTATOC PET/CT revealed the neuroendocrine origin of these lesions, confirmed by biopsy. However, the primary site of the neuroendocrine tumor remained unclear, leaving primary hepatic neuroendocrine tumor and neuroendocrine cancer of unknown primary as possible diagnostic options.