Pulmonary artery choriocarcinoma mimicking pulmonary thromboembolism: a case report

Introduction

Choriocarcinoma, a rapidly invasive, metastatic neoplasm, mostly involves the female genital tract after a gestational event, such as molar pregnancy, term pregnancy, abortion, or ectopic pregnancy. Pulmonary locations are among the common sites in which metastases spread hematologically (1). Primary pulmonary artery choriocarcinoma is extremely rare. Clinical signs of primary pulmonary artery choriocarcinoma in documented reports include coughing, hemoptysis, hemothorax, and chest pain (2,3), which are similar to those of pulmonary thromboembolism (PTE). Here, we describe a unique case of primary pulmonary artery choriocarcinoma that was considered to be a pulmonary embolism (PE) prior to pathological analysis. The study highlights the elevated suspicion for pulmonary artery tumor and invasive diagnostic assessments in PTE cases that are unresponsive to standard anticoagulation therapy. We present this case in accordance with the CARE reporting checklist (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2024-2461/rc).

Case presentation

A 32-year-old woman presented with a 2-month history of severe coughing, hemoptysis, and chest pain. Prior to this visit, the patient had not undergone any treatment for these symptoms. Physical examination was unremarkable. Due to irregular menstruation, she had been taking oral contraceptives (Uraxel) intermittently for the preceding 2 months. Previously, the patient had delivered two healthy babies in series and had two elective terminations of pregnancy as a result of family planning.

Laboratory analysis revealed a slight rise in inflammatory parameters, with a D-dimer value within the normal range of 410 ng/mL (normal range, <500 ng/mL) (Figure 1). A PE was subsequently detected on computed tomography pulmonary angiography (CTPA) (Figure 2A-2C). Although D-dimer levels were in normal range or slightly higher on multiple measurements (Figure 1), suspicion for PTE remained high due to typical symptoms and history of oral contraceptive usage. During hospitalization, we initiated warfarin therapy and concurrently administered low-molecular-weight heparin for overlapping treatment until the international normalized ratio (INR) achieved the therapeutic range. The patient reported relief of chest pain and cough after administration of anticoagulation therapy. Given the patient’s refusal to undergo frequent INR examination, rivaroxaban was prescribed for continued post-discharge therapy.

Figure 1 The change curve of D-dimer over the course of treatment. D-dimer was not noticeably elevated across multiple measurements.

Figure 2 Pulmonary CT scan. (A-C) Pulmonary CT showed a pulmonary artery filling defect. (D-F) Pulmonary CT scan after anticoagulant therapy. Compared with prior to anticoagulant treatment, the pulmonary artery filling defect was increased on pulmonary CT (red arrows), indicating that anticoagulant treatment was ineffective and the patient’s lesions had worsened. CT, computed tomography.

One month later, there was a noticeable decrease in her hemoglobin level, and she began experiencing severe uterine bleeding. Immediately after cessation of anticoagulation medication, uterine compression was applied to halt bleeding and amenorrhea. The PE did not resolve and rather progressed on subsequent CT scans (Figure 2D-2F). Test for thrombotic genes mutation produced negative results.

At this point, the possibility of alternative diagnoses was raised. In order to further confirm the diagnosis, positron emission tomography-computed tomography (PET/CT) scan was performed and demonstrated that the embolism was hypermetabolic (Figure 3). The patient’s abnormal uterine bleeding also prompted us to check β-human chorionic gonadotropin (β-HCG) levels, which revealed a notable elevation (Figure 4). Therefore, the initial diagnosis was significantly challenged in view of the hypermetabolic embolism and elevated β-HCG.

Figure 3 ¹⁸F-FDG PET/CT changes before and after chemotherapy. (A-E) The integration of PET-CT findings indicated embolism in the distal left main pulmonary artery and branches, varying degrees of increased glucose metabolism (maximum standardized uptake value 7.2) (red arrows), and multiple infarcts in the left lung. (F-J) After 10 courses of chemotherapy, including fluorouracil, vincristine, and actinomycin, repeat ¹⁸F-FDG PET/CT imaging showed a decrease in the size of the embolism and the uptake of fluorodeoxyglucose. The red arrows indicated that tumor thrombus has disappeared after 10 courses of chemotherapy. ¹⁸F-FDG PET/CT, ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography.

Figure 4 The change curve of β-HCG during the course of treatment. β-HCG levels declined quickly after primary pulmonary artery choriocarcinoma was diagnosed and chemotherapy administered. β-HCG, β-human chorionic gonadotropin.

Right-sided heart catheterization revealed a left pulmonary artery mass with stenosis and occlusion. Based on these findings, a percutaneous catheter pulmonary artery biopsy was performed. Pathological examination indicated a gestational trophoblastic neoplasm (GTN), specifically identified as a choriocarcinoma (Figure 5). Cervical smears and pelvic magnetic resonance imaging (MRI) showed no signs of cervical cancer, despite PET/CT with slight uptake in the uterus. Given these findings, the diagnosis was ultimately primary pulmonary artery choriocarcinoma.

Figure 5 The patient underwent left- and right-sided heart catheterization and percutaneous catheter pulmonary artery biopsy. Multipoint tissue was sampled from the mass lesion of the left lower pulmonary artery. Immunohistochemistry included (A) hematoxylin and eosin staining and yielded the following results: (B) CK7 (++), (C) TTF1 (−), (D) CK5/6 (−), (E) P63 (++), (F) MUC4 (++), (G) Ki67 (80%+), and (H) HCG (+++). Immunophenotyping showed choriocarcinoma in the gestational trophoblastic tumor (magnification 200×).

According to the anatomical staging of trophoblastic tumors established by the International Federation of Gynecology and Obstetrics in 2000, the pulmonary artery choriocarcinoma was classified as stage 3. Ten rounds of treatment with fluorouracil, vincristine, and actinomycin were administered. During the course of treatment, the patient did not experience any serious adverse reactions that required discontinuation or change of treatment plan. During one-year follow-up, the patient reported complete relief of initial symptoms. Moreover, β-HCG detection and imaging examination indicated improvement (Figures 4,6). As of this year, the patient remains disease-free and all follow-up examinations have shown no evidence of recurrence. An overview of the patient’s diagnosis and treatment is shown in Figure 7.

Figure 6 Pulmonary CT of the latest follow-up. After chemotherapy, the patient reported no discomfort, and the latest follow-up CT showed that the left lower pulmonary artery had been occluded, while the original embolism had disappeared. The red arrow indicates tumor thrombus. CT, computed tomography.

Figure 7 Diagnosis and treatment list. CT, computed tomography; PT, prothrombin time; APTT, activated partial thromboplastin time; INR, international normalized ratio; PET, positron emission tomography; β-HCG, β-human chorionic gonadotropin.

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This report was approved by the Ethics Committee of Guangdong Provincial People’s Hospital (ethics code: KY-Q-2022-143). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

International Multidisciplinary Team (iMDT) discussion

Discussion among physicians from Guangdong Provincial People’s Hospital

Department of Pulmonary and Critical Care Medicine

The patient in this case initially exhibited symptoms including cough, haemoptysis, and chest pain. Initial diagnosis of PTE was established despite a normal D-dimer level, attributed to the patient’s history of oral contraceptive use and the presence of filling defects in the pulmonary artery. Nevertheless, the ineffectiveness of standard anticoagulation therapy and the occurrence of vaginal bleeding after the initiation of treatment, posed challenges to our initial diagnosis. When standard anticoagulation therapy was ineffective in treating PE, a PET/CT scan was advised to ascertain the presence of tumors or other diseases.

Tumors that arise from the main pulmonary artery or pulmonary valve are designated as primary pulmonary artery tumors (PPATs), with pulmonary sarcoma being recognized as the predominant subtype within this classification (4-6). The spectrum of documented PPATs also includes pulmonary myxomas and papillary fibroelastomas (7-9). The differential diagnoses for these clinical manifestations include infection, structural cardiac abnormalities, pulmonary hypertension, and trauma (10-12). Patients are frequently misdiagnosed with PTE because of its nonspecific symptoms, including dyspnoea, cough, haemoptysis, chest pain, and vascular occlusion. PPATs commonly involve the large-caliber pulmonary vasculature, including the main pulmonary artery trunk and the right or left pulmonary arteries, which can subsequently lead to involvement of the pulmonary valve and the right ventricular outflow tract. These tumors pose diagnostic challenges due to the nonspecific nature of their symptoms, lacking pathognomonic signs. In this case, the hypermetabolic embolic lesion detected on PET/CT scan indicated a high probability of a pulmonary artery tumor, thereby warranting a definitive pathological assessment for diagnosis.

Department of Interventional Cardiology

Upon the patient’s initial presentation, a CTPA revealed filling defects and occlusive changes within the main and branch vessels of the left pulmonary artery. These alterations resulted in reduced perfusion to the left lung, which were indicative of PE and pulmonary infarction. Nevertheless, the administration of anticoagulation therapy resulted in minimal amelioration of both the clinical symptoms and the radiographic findings. Tumors can mimic or coexist with conditions like pneumonia or embolism, potentially causing delayed diagnosis.

Her PET scan showed an increased standard uptake value (SUV) in the left pulmonary artery (SUVmax: 7.2), suggesting a high likelihood of malignancy. In this case, the embolism was situated within the blood vessel and in proximity to the pleura, making it difficult to obtain biopsy via bronchoscopy. We also had to give up lung puncture biopsy because of the high-risky of bleeding. Consequently, percutaneous right-sided heart catheterisation (RHC) and pulmonary artery biopsy could be more feasible. Defects were identified in the main left pulmonary artery, the main left lower pulmonary artery, and the branches of the left upper pulmonary artery. Biopsies were obtained from the catheter at the lesion in the left lower pulmonary artery. The diagnosis of a pulmonary artery tumor was then deemed more probable.

Department of Gynecology

Firstly, in a patient with PE and significant uterine haemorrhage during anticoagulation, the foremost priority was to manage the bleeding effectively. Uterine compression haemostasis and drug-induced amenorrhoea were utilized. Secondly, the patient’s obstetric history indicated she was gravida 4, para 2, having two healthy children, one medication-induced abortion a decade ago, and a curettage for incomplete abortion five years prior. For women of childbearing age presenting with abnormal uterine bleeding, β-HCG testing was essential. Her β-HCG level was significantly elevated at 60,072 mIU/mL. Considering her history of irregular uterine bleeding, pregnancies, and elevated β-HCG levels, the potential of a trophoblastic tumor was highly suspicious. For this patient, pathological examination by pulmonary artery biopsy indicated a GTN, specifically identified as a choriocarcinoma.

Choriocarcinoma is a form of GTN that typically arises in the corpus uteri, while occurrences outside the corpus uteri are comparatively uncommon. Reported cases of choriocarcinoma are limited to the cervix (13), ovaries (14), fallopian tubes (15), and vagina (16), with rare instances of primary choriocarcinoma in the pulmonary artery (17). For this patient, choriocarcinoma was confirmed through pathological analysis. Furthermore, it was necessary to differentiate between primary pulmonary artery choriocarcinoma and metastatic pulmonary artery choriocarcinoma. PET imaging revealed a slightly increased SUV in the uterine area, whereas Thinprep cytologic test (TCT) and pelvic MRI showed no signs of malignancy. The diagnosis of primary pulmonary artery choriocarcinoma has been established. According to the anatomical staging of trophoblastic tumors established by the International Federation of Gynecology and Obstetrics in 2000, the pulmonary artery choriocarcinoma was classified as stage 3. The patient received chemotherapy comprising fluorouracil, vincristine, and dactinomycin. PET scan following chemotherapy indicated a reduction in metabolic activity of the previously identified hypermetabolic lesion in the left pulmonary artery. She was presently in remission, with normal β-HCG values. Thus, detection of elevated β-HCG levels and pathological biopsy led to an accurate diagnosis, facilitating timely and effective treatment that ultimately preserved the patient’s life.

Questions to be discussed

When PE is suspected in a patient without hemodynamic instability, what actions should be undertaken first?

Expert opinion 1: Bryan S. Benn

While PE may present with hemodynamic instability as in the case of a massive PE or a submassive PE, often the presentation will be one of hemodynamic stability. In these cases, it is imperative to obtain an appropriate history to evaluate for possible etiologies as the management of provoked versus unprovoked PE is quite different. Clinical evaluation with laboratory data, including D-dimer, and imaging studies, such as chest CT with contrast or ventilation perfusion scan for those patients in which IV contrast is contraindicated, is also essential. Additionally cardiac and lower extremity ultrasound plays an important role in assessing hemodynamics and clot burden, respectively.

Expert opinion 2: Hiren J. Mehta

(I) Assess clinical probability of PE

Use a risk assessment tool like the Wells score or the Geneva score to estimate the likelihood of PE. This helps guide further diagnostic testing and treatment.

• Wells score considers factors like clinical signs of deep vein thrombosis (DVT), prior history of PE or DVT, cancer, recent surgery or immobility, hemoptysis, and alternative diagnoses. Each variable is assigned a certain point and based on total score it can classify patients into low risk (<2), intermediate risk (2–6 points) and high risk (>6 points).
• Geneva score also incorporates factors such as age, previous PE or DVT, surgery or trauma, and clinical signs of DVT.

(II) Obtain initial diagnostic testing

• If based on above scoring patient has low probability consider following testing
  D-dimer measurement: a negative D-dimer test can rule out PE in patients with a low clinical probability. However, a positive result alone is not diagnostic, as D-dimer levels can be elevated in other conditions.

(III) Next steps

For patients with intermediate to high risk on initial screening test or for those with low risk and elevated D-dimer consider.

• Imaging:
  • CTPA is the gold standard for diagnosing PE and should be performed in patients with moderate to high pretest probability;
  • Ventilation-perfusion (V/Q) scan is an alternative if a CTPA is contraindicated (e.g., due to contrast allergies or renal failure). It is particularly useful in pregnant patients or those with severe contrast allergies;
  • Ultrasound of the legs is useful if DVT is suspected, as it can help identify a clot that might be embolizing to the lungs (18).

Expert opinion 3: Kim Styrvoky

In hemodynamically stable patients with suspected PE, it is important to adopt a systematic approach for the diagnosis of PE to avoid risks of unnecessary testing. This begins with initial patient history and physical examination. Determination of the pre-test probability for PE can be performed using qualitative or quantitative means to determine low, intermediate or high probability of PE for the patient. Patients with high-probability would then undergo a CTPA and if inconclusive, a ventilation-perfusion scan. Patients with intermediate probability would then have D-dimer testing, and if elevated >500 ng/mL or per age-adjusted D-dimer thresholds, proceed with the similar testing as high risk patients; if not elevated, then PE likely excluded and no further testing generally recommended. For low probability patients, then use the PE rule out criteria (PERC); if unable to rule out PE, then would proceed with the pathway for intermediate probability patients. Depending on patient characteristics, and anticipated time for testing, empiric anticoagulation can be considered (19,20).

Expert opinion 4: Sylvia S. Yong

Clinical pre-test probability is important in the initial standardized approach to the diagnostic algorithm for possible thromboembolism. While empiric treatment is considered in select limited scenarios such as acute hypoxemic respiratory failure with instability and inability to safely travel for diagnostic imaging or clinical concern for obstructive shock, thoughtful diagnostic approach is warranted in patients with hemodynamic stability to establish an accurate diagnosis given the non-trivial risks of anticoagulation. Two commonly used clinical tools are the Wells rule and revised Geneva score can assist with objective measure of clinical probability of thromboembolic disease. For patients with pregnancy, a YEARS criterion has been recently implemented for assistance with risk stratification and pursuing diagnostic evaluation (21). In the setting of unlikely probability of PE, a negative D-dimer can assist with ruling out PE due to its negative predictive value. However, in those with high clinical concern, a CTPA should be pursued for definitive diagnostic evaluation and is the standard of care.

What is the role of D-dimer in distinguishing PTE from PPATs?

Expert opinion 1: Bryan S. Benn

The role of the D-dimer laboratory test is quite informative depending on the clinical situation. A negative D-dimer value will effectively rule out a PE if the clinical scenario is one of low probability based on established criteria. However, a positive value for D-dimer is less valuable as numerous other conditions may also give an elevated value. Thus, the D-dimer value must be interpreted in the context of the clinical scenario. When there is discordance between the laboratory value and the clinical situation, maintaining a broad differential for alternative explanations is important.

Expert opinion 2: Hiren J. Mehta

• D-dimer is a fibrin degradation product that is elevated in the presence of thrombotic events, such as PE. In PE, the formation and subsequent breakdown of thrombi in the pulmonary arteries result in the release of D-dimer into the bloodstream. This leads to an elevated D-dimer level.
• PPATs (such as pulmonary artery sarcoma, the most common type of malignant tumor in the pulmonary arteries) are rare and are not typically associated with the same pathophysiological mechanisms as PE and do not usually cause thrombus formation or fibrin breakdown in the same way that PE does (22). Thus, D-dimer levels are often not significantly elevated in cases of PPATs, especially when there is no associated thrombosis.
• High D-dimer levels strongly suggest a thrombotic event, such as PE, but do not rule out a PPAT, as these tumors may not affect fibrin degradation.

Expert opinion 3: Kim Styrvoky

D-dimer is a test used in the evaluation pathway for patients with suspected PE. At a large cancer center, among 8,023 cancer patients, 1,156 (14%) had PE, with only 35 with PE with normal plasma D-dimer levels (23). Studies have shown that patients with pulmonary artery tumors often have D-dimer levels within the normal range. Thus, this test may be helpful in differentiating between pulmonary artery tumors and PE (23-25).

Expert opinion 4: Sylvia S. Yong

As a marker of fibrinolysis, D-dimer is often elevated in acute thrombotic disease, however it is non-specific and can be elevated in other clinical conditions such as malignancy, sepsis, pregnancy, and myocardial infarction as well as elevation with age, which can lead to more false positive tests. As a result, the role of D-dimer in distinguishing thromboembolic disease and malignancy is limited.

What should we do next for patients suffering from PE if standardized anticoagulant therapy is ineffective?

Expert opinion 1: Bryan S. Benn

When treatment with standard anticoagulant therapy is ineffective for patients with PE, further evaluation for why treatment failure occurred is needed. As the etiology of treatment failure can often be traced to medication non-adherence/non-compliance, complex drug-drug interactions, and unidentified underlying medical conditions that impact the clotting cascade, these possibilities must be addressed. In the absence of a clear explanation, the possibility that a different disease process is masquerading as a PE must be entertained as well.

Expert opinion 2: Hiren J. Mehta

Before escalating therapy, it’s important to determine why the anticoagulation might be ineffective. Potential causes include:

• Inadequate anticoagulation dosing (e.g., suboptimal dose or timing of anticoagulant administration);
• Drug resistance or interactions (e.g., certain medications can interact with anticoagulants, reducing their efficacy);
• Anticoagulant-related complications [e.g., heparin-induced thrombocytopenia (HIT) or issues with drug absorption, especially with direct oral anticoagulants (DOACs)];
• Suboptimal pharmacokinetics (e.g., renal or hepatic dysfunction that affects drug metabolism);
• Recurrent or massive PE despite anticoagulation;
  Testing for specific conditions [e.g., anti-Xa levels or prothrombin time (PT)/INR for warfarin] may help identify.
  If the patient is not responding to initial therapy, escalation may be necessary (26):
• Increase the dose of anticoagulants [especially in patients on weight-based therapy like low molecular weight Heparin (LMWH) or when using unfractioned heparin (UFH), you may need to increase the infusion rate];
• Switch anticoagulants: if the patient is on one type of anticoagulant, consider switching to a different class. For example, patients on warfarin or DOACs who are not responding may benefit from UFH or LMWH, which offer more predictable pharmacokinetics and are easier to adjust;
• Monitoring therapeutic levels: check anti-Xa levels or PT/INR to ensure that the anticoagulant therapy is at therapeutic levels. For instance, LMWH therapy can be adjusted based on anti-Xa levels if needed;
• Thrombophilia workup: if there is suspicion of a hypercoagulable state that might be contributing to recurrent thrombus formation.
  Consider thrombolysis, thrombectomy and or inferior vena cava (IVC) filter.
  Consider alternative diagnosis including pulmonary artery tumor embolism etc.

Expert opinion 3: Kim Styrvoky

For patients with PE who fail standard anticoagulation therapy with persistent symptoms or progression of disease, then diagnostic and evaluation pathway should depend on clinical stability. In hemodynamically stable patients, consideration for medication non-adherence, anticoagulation failure or evaluation for alternative diagnosis should commence. In patients who are hospitalized and hemodynamically unstable, then multi-disciplinary discussion should occur to determine the optimal additional therapy depending on local availability: systemic thrombolytic therapy, surgical embolectomy, catheter directed thrombolytics or clot extraction. Patients who are unstable may require venoarterial extracorporeal membrane oxygenation (V-A ECMO) as a bridge to definitive therapy (19,27,28).

Expert opinion 4: Sylvia S. Yong

Oral anticoagulation is effective for treatment of thromboembolism and refractory events while on treatment is rare at approximately 2 per 100 patient-years. As the most common reasons for recurrence are due to subtherapeutic drug levels and non-adherence, these should be verified. Subsequently, contributing factors such as treatment of underlying disease state that leads to hypercoagulable state, particularly malignancy should be addressed. In the absence of known malignancy, other hypercoagulable states such as antiphospholipid syndrome should be considered (29).

Patient perspective

Initially, when I started experiencing symptoms of coughing, chest pain, and hemoptysis, I felt my life was severely impacted. The diagnostic process was initially vague and unsettling for me. The array of tests and the uncertainty of waiting times caused me anxiety. However, the professionalism and compassion of the medical team reassured me. They patiently explained each step, providing clarity about my condition. After a lengthy diagnostic process confirmed my illness, I underwent chemotherapy, which significantly changed my life. Although I experienced side effects such as nausea and loss of appetite during the treatment, my symptoms of coughing, chest pain, and hemoptysis were noticeably alleviated. Moreover, the doctors and nursing team were very attentive to my feelings. Despite the challenges, I am grateful for the quality of medical care I received.

Conclusions

Due to its uncommon prevalence and non-specific symptoms, primary pulmonary artery choriocarcinoma is often initially misdiagnosed as PTE. There are two key points we learned from this case. First, when symptoms and imaging are consistent, but the level of D-dimer is not elevated and there is lack of clinical response to anticoagulation, the diagnosis of PTE should be questioned and other diagnoses should be considered. Second, early detection of β-HCG levels in women with concern for possible gynecologic malignancy is imperative. As it is a risk factor for both PTE and several gynecological neoplastic illnesses, history of oral contraceptive use may be taken into consideration for both differential diagnoses.

Acknowledgments

We would like to thank the patient described in this report and the Pathology Department and Nuclear Medicine Department of Guangdong Provincial People’s Hospital.

Funding: None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2024-2461/rc

Peer Review File: Available at https://tcr.amegroups.com/article/view/10.21037/tcr-2024-2461/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-2024-2461/coif). K.S. receives travel/lodging payments from Intuitive Surgical, Inc. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This report was approved by the Ethics Committee of Guangdong Provincial People’s Hospital (ethics code: KY-Q-2022-143). Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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(English Language Editor: J. Gray)