Congenital anomalies and pericardial masses

Article written and reviewed by Dr Luca Moretti

Congenital anomalies and pericardial masses include very different structural conditions: defects in sac formation, mesothelial cavities, communicating outpouchings, and acquired solid or cystic lesions. Their anatomical proximity to the heart does not imply the same origin or the same risk. Many are identified incidentally, whereas others alter filling, compress adjacent structures, or represent a manifestation of oncologic disease.

A pericardial cyst is generally a benign, noncommunicating lesion; a pericardial diverticulum retains a connection with the cavity. Congenital absence of the pericardium, by contrast, raises issues of cardiac support and anatomical relationships, with important differences between complete and partial defects. These conditions must be distinguished from loculated collections, hematomas, tumors, and mediastinal structures that mimic their appearance.

The diagnostic pathway is based on four connected questions: which structure is involved, what the nature of the lesion is, what consequences it produces, and whether tissue needs to be obtained. Reliable characterization can prevent an unnecessary intervention or allow timely recognition of a compressive or infiltrative lesion. Multimodality imaging is central, but it should answer specific clinical questions rather than become an automatic sequence of tests.

Origin, classification, and anatomical relationships

The pericardium develops through embryologic processes that separate the thoracic cavities and organize the serosal lining. Abnormalities in these processes may leave defects of varying extent or mesothelial cavities. The term congenital describes the origin, not the time of discovery: an anomaly may remain silent until adulthood. Late detection therefore does not demonstrate recent acquisition, especially when previous imaging was unavailable or was not directed at the pericardium.

Cystic cavities have walls and contents that guide interpretation. A simple mesothelial cyst generally has fluid content, regular margins, and no vascularized solid components. A diverticulum differs because it communicates with the sac, and this connection may be thin and not demonstrable on every examination. Changes in shape or volume with position and filling conditions may suggest communication, but failure to visualize the tract does not guarantee that the lesion is a closed cyst.

Defects of the sac are described by side, extent, and residual margins. Complete or extensive absence allows abnormal cardiac mobility and is often well tolerated; a partial defect may instead create an edge through which part of the heart can herniate and become compressed. The relationship between size and risk is therefore not linear. The anatomical description should specify which chambers or coronary structures lie near the margin rather than stopping at the word agenesis.

Acquired masses include benign tumors, malignant neoplasms, and pseudomasses. Secondary involvement from extracardiac tumors is overall more common than primary pericardial neoplasms. The latter include rare entities such as mesothelioma, but a mass cannot be classified histologically on location alone. Nodularity, infiltration, and effusion may guide suspicion; a neoplastic collection can also occur without an evident mass, as in some forms of neoplastic pericarditis.

A pseudomass may correspond to prominent fat, a distended pericardial recess, loculated fluid, a clot, or a procedural sequela. Bronchogenic cysts, enteric duplication cysts, and other mediastinal lesions may lie very close to the pericardium without arising from it. The first useful classification is therefore topographic: intrapericardial, pericardial, or extrapericardial. This step changes both the differential diagnosis and the safest route for any sampling.

Assessment of anatomical relationships includes cardiac chambers, coronary arteries, great vessels, bronchi, esophagus, and phrenic nerves. A small lesion in a critical location may have greater consequences than a larger one growing into free space. Previous interventions alter these relationships and may produce adhesions or organized hematomas. The observed anatomy must be compared with the clinical history, avoiding automatic attribution of every regular finding to congenital development or every focal thickening to a tumor.

Mechanisms of symptoms and clinical assessment

Most simple findings are discovered during examinations performed for other reasons. In this setting, clinical correlation is decisive: chest pain, palpitations, and dyspnea are common even without a causal pericardial lesion. Attributing them immediately to the finding may lead to interventions that do not improve symptoms. The timeline should be reconstructed, the location and function assessed for plausibility of an effect, and alternative cardiac, respiratory, and musculoskeletal disorders considered.

The compressive effect depends on location, consistency, and the capacity of surrounding structures to adapt. A cyst or mass can interfere with chamber filling, narrow a venous structure, or compress an airway, producing dyspnea, cough, or congestion. Mere contiguity on imaging does not prove obstruction: significant deformation, altered flow, or other consistent findings are needed. A relationship between symptoms and posture may suggest a dynamic component but does not by itself identify a specific anomaly.

In partial pericardial defects, risk arises from herniation and possible strangulation of cardiac structures through the residual edge. Persistent pain, syncope, or ischemic signs require a different level of concern from a large area of absence without compression. Positional abnormalities can alter the electrocardiogram and echocardiographic views, mimicking dilation or wall-motion abnormalities. Recognizing the anatomical context avoids diagnosing structural heart disease on the basis of nonstandard projections.

Systemic manifestations favor an acquired cause: fever, weight loss, lymphadenopathy, or a known malignancy changes the probability of the different diagnoses. However, a patient with cancer may also have a pre-existing benign cyst, and the absence of systemic symptoms does not exclude a malignant lesion. Assessment should include previous radiotherapy, immunosuppression, infections, and procedures. Mass characteristics and the temporal trajectory carry more weight than any single isolated historical feature.

The physical examination looks for signs of congestion, low output, and respiratory compromise, although it is often normal in incidental anomalies. A lesion associated with effusion may cause tamponade; an infiltrative process may cause constriction. These mechanisms should be assessed separately from mass volume. Urgency is defined by the effect on circulation, possible complications, and rate of evolution, not solely by the label of tumor or congenital anomaly.

Comparison with previous studies distinguishes prolonged stability from recent growth and may show that an apparently new lesion was already present. Measurements should be comparable in plane and technique: an apparent difference may reflect posture, respiration, or a different reconstruction. Documented growth requires explanation but does not automatically prove malignancy; hemorrhage or inflammation can also enlarge a cavity. Conversely, long-term stability supports benignity without necessarily resolving every anatomical or functional question.

Multimodality characterization and differential diagnosis

Echocardiography is often the first examination used to assess chambers, flows, and associated collections. A simple cavity may appear anechoic, whereas a solid mass has internal echoes; this distinction is limited, however, by location, acoustic window, and contents. Organized blood or protein-rich fluid can mimic solid tissue. Doppler helps identify vascular structures and compressive effects, but the absence of detectable flow does not by itself permit a definitive histologic diagnosis.

CT defines thoracic anatomy and relationships with vessels, airways, and the mediastinum, identifying fat, calcification, and content attenuation. A simple cyst tends not to show internal enhancement, whereas vascularized tissue or irregular walls require further evaluation. Proteinaceous or hemorrhagic contents may increase density and make differentiation less straightforward. The contrast protocol is chosen according to the clinical question, renal function, and any need to map vascular structures.

Cardiac MRI combines anatomy, motion, and tissue characterization without ionizing radiation. T1- and T2-weighted sequences, fat suppression, and post-contrast imaging help distinguish fluid, adipose tissue, and solid components. No single signal should be interpreted out of context: protein concentration and hemorrhage alter the behavior of cysts. Cine imaging can clarify abnormal mobility and the relationship of a cardiac portion to the margin of a pericardial defect.

In pericardial absence, failure to visualize the thin pericardial layer is not sufficient, especially where surrounding fat is sparse. Concordant signs are needed, such as displacement and rotation of the heart, abnormal interposition of lung, and demonstration of the margins when present. CT and MRI are complementary in defining the extent. Careful assessment should look for features that modify risk, including herniation, rather than stopping at the generic confirmation of a nonvisualized pericardium.

PET may contribute to staging and biopsy-site selection when there is an appropriate oncologic suspicion. Uptake does not automatically distinguish malignancy from inflammation and is not necessary for every typical cyst. Blood or tumor markers likewise do not replace anatomical assessment. Any associated effusion is analyzed according to clinical indication: negative cytology and absence of tumor cells do not exclude every form of pericardial involvement, especially when the lesion is focal.

Biopsy is useful if it can concretely change treatment and if the risk is acceptable. In a patient with extracardiac disease, sampling a lymph node or another safer site may be preferable. Vascular lesions and some cystic formations require particular caution before puncture; the route should be planned on imaging. The decision may be observation, excision, or targeted sampling, without imposing histologic proof on every characteristic benign finding.

Treatment principles and choosing between observation and intervention

Observation is appropriate for many well-characterized asymptomatic anomalies without functional effects. This choice requires a sufficiently reliable diagnosis, a useful baseline for comparison, and a plan consistent with the remaining uncertainty. It does not mean ignoring a lesion, but avoiding an intervention whose risk exceeds the expected benefit. A stable typical cyst, a large defect without herniation, and an infiltrative mass do not share the same pathway simply because all belong to the pericardial region.

For cystic lesions, attributable symptoms, significant compression, documented growth, or uncertain features may favor treatment. Aspiration and resection have different goals: the former reduces volume but may leave a wall capable of reaccumulating fluid; the latter provides tissue and may be definitive, with its own surgical risks. Location, anatomical relationships, and diagnostic probability guide the choice. There is no single universally validated diameter that mandates excision independently of all other features.

In diverticula, communication and any dynamic variation in contents should be considered before applying a treatment designed for a closed cyst. The distinction may remain uncertain until exploration, but preoperative suspicion changes planning. In sac defects, by contrast, intervention aims to prevent herniation or compression and may involve reconstruction or enlargement of the margin according to the anatomy. The choice requires specific expertise and an assessment of individual structural risk.

Neoplastic masses require a strategy linked to histology and extent. Surgery, systemic therapy, and radiotherapy have different roles in primary tumors and secondary involvement. A technically feasible resection is not automatically useful if disease is disseminated; conversely, a localized benign but compressive lesion may warrant treatment. Drainage of a symptomatic effusion addresses one consequence and should be integrated with treatment of the malignancy when indicated and consistent with goals of care.

A hemodynamic complication changes priorities. Tamponade, critical compression, or suspected cardiac strangulation cannot wait for an elective surveillance program. Urgent imaging should provide necessary information without delaying life-saving treatment. Congenital anomalies can also coexist with acquired pericardial disease: an inflammatory effusion does not become benign because the patient also has a known cyst. Each mechanism should be recognized and treated according to its own impact.

Multidisciplinary discussion integrates cardiology, radiology, surgery, and, when needed, oncology and pathology. It is particularly useful when the lesion lies near coronary arteries or phrenic nerves, when sampling is risky, or when symptoms have no clear correlation. Anti-inflammatory drugs, anticoagulants, and antibiotics are not generic treatments for structural anomalies. They should be prescribed only for a distinct and documented indication, avoiding empiric treatment that delays necessary characterization.

Prognosis, complications, and surveillance over time

The natural history depends on the diagnosis. Observations of simple cysts frequently show stability and, in some cases, reduction in size; however, these data come from limited cohorts and do not describe every mediastinal cystic lesion. Large pericardial defects are often well tolerated, whereas certain partial forms carry a specific anatomical risk. Malignant masses have a prognosis determined mainly by type, extent, and treatment response, which cannot be inferred from location alone.

Compressive complications include interference with filling or venous outflow and, in some locations, respiratory obstruction. Infection, hemorrhage, or rupture of a cavity are reported but rare events; they should not be presented as the expected evolution of every incidental cyst. In partial defects, herniation with vascular compromise requires a distinct assessment. Risk is estimated from morphology and observed consequences, while acknowledging the limitations of case series and the absence of universally validated predictive models.

The follow-up program should be proportional to risk and to the quality of the initial diagnosis. An indeterminate lesion may require short-interval comparison or further investigation; a stable benign finding does not necessarily justify frequent CT scans for life. Echocardiography and MRI can reduce radiation exposure when they provide adequate visualization. Interval, duration, and modality should be justified because there is no single schedule applicable to cysts, diverticula, defects, and tumors.

Image comparability prevents decisions based on technical differences. Position, respiratory phase, measurement plane, and acquisition method can alter the apparent diameter. When a change is real, its cause should be sought and its effect on surrounding structures assessed. Follow-up should not be reduced to a number: new irregular margins, solid components, enhancement, or associated effusion may matter more than a small isolated increase in maximum size.

After an intervention, surveillance considers completeness of resection or repair, histology, residual collections, and symptom recovery. Failure of symptoms to improve should prompt reconsideration of the initial causal link or a concomitant disorder. After procedures for congenital defects, documenting the anatomical result is useful for future thoracic interventions. In tumors, follow-up also follows the oncologic pathway, integrating local recurrence, systemic disease, and possible cardiac effects of treatment.

Patient education should distinguish a stable finding from warning signs requiring reassessment: new or persistent pain, syncope, increasing dyspnea, fever, or signs of congestion should not automatically be attributed to the known diagnosis. Physical activity and restrictions depend on actual functional risk and any associated heart disease. Clear documentation of the nature, location, and rationale for the strategy avoids repeated diagnostic work and allows decisions to be updated when the clinical picture changes.

Bibliography
1. Schulz-Menger J et al. 2025 ESC Guidelines for the management of myocarditis and pericarditis. European Heart Journal. 2025;46(40):3952-4041.
2. Klein AL et al. Pericardial Diseases: International Position Statement on New Concepts and Advances in Multimodality Cardiac Imaging. JACC: Cardiovascular Imaging. 2024;17(8):937-988.
3. Adler Y et al. 2015 ESC Guidelines for the diagnosis and management of pericardial diseases: The Task Force for the Diagnosis and Management of Pericardial Diseases of the European Society of Cardiology (ESC). Endorsed by: The European Association for Cardio-Thoracic Surgery (EACTS). European Heart Journal. 2015;36(42):2921-2964.
4. Parmar YJ, Shah AB, Poon M, Kronzon I. Congenital Abnormalities of the Pericardium. Cardiology Clinics. 2017;35(4):601-614.
5. Kar SK, Ganguly T. Current concepts of diagnosis and management of pericardial cysts. Indian Heart Journal. 2017;69(3):364-370.
6. Khayata M, Alkharabsheh S, Shah NP, Klein AL. Pericardial Cysts: a Contemporary Comprehensive Review. Current Cardiology Reports. 2019;21(7):64.
7. Alkharabsheh S et al. Clinical Features, Natural History, and Management of Pericardial Cysts. American Journal of Cardiology. 2019;123(1):159-163.
8. Shah AB, Kronzon I. Congenital defects of the pericardium: a review. European Heart Journal - Cardiovascular Imaging. 2015;16(8):821-827.
9. Khayata M et al. Case series, contemporary review and imaging guided diagnostic and management approach of congenital pericardial defects. Open Heart. 2020;7(1):e001103.
10. Roberts WC. Pericardial heart disease: its morphologic features and its causes. Proceedings (Baylor University Medical Center). 2005;18(1):38-55.
11. Mori S et al. Pericardial effusion in oncological patients: current knowledge and principles of management. Cardio-Oncology. 2024;10:8.
12. Lyon AR et al. 2022 ESC Guidelines on cardio-oncology developed in collaboration with the European Hematology Association (EHA), the European Society for Therapeutic Radiology and Oncology (ESTRO) and the International Cardio-Oncology Society (IC-OS). European Heart Journal. 2022;43(41):4229-4361.
13. Saab J et al. Diagnostic yield of cytopathology in evaluating pericardial effusions: Clinicopathologic analysis of 419 specimens. Cancer Cytopathology. 2017;125(2):128-137.