Overview
Definition:
Pediatric mediastinal masses are abnormal growths located within the mediastinum, the central compartment of the thoracic cavity
Resection refers to the surgical removal of these masses, aiming for complete excision to establish a diagnosis, relieve symptoms, and prevent recurrence or malignant transformation.
Epidemiology:
Mediastinal masses in children are relatively uncommon but represent a diverse group of pathologies
Their distribution varies with age, with anterior mediastinal masses more common in adolescents and posterior masses in younger children
Incidence is approximately 0.13 cases per 100,000 children annually
Certain types like germ cell tumors and lymphomas are more prevalent in specific age groups.
Clinical Significance:
Accurate diagnosis and timely surgical intervention are crucial for optimal patient outcomes
Many pediatric mediastinal masses, if left untreated, can lead to significant morbidity and mortality due to compression of vital structures, malignant potential, or systemic effects
A well-defined surgical approach is vital for safe and effective resection, minimizing complications, and facilitating definitive histopathological diagnosis.
Clinical Presentation
Symptoms:
Asymptomatic presentation discovered incidentally on imaging
Respiratory symptoms: Cough
Dyspnea
Wheezing
Tachypnea
Chest pain
Symptoms of superior vena cava (SVC) syndrome: Facial and upper extremity edema
Distended neck veins
Fever and constitutional symptoms: Especially with infections or lymphomas
Neurological symptoms: Horner's syndrome
Spinal cord compression symptoms
Dysphagia
Hoarseness.
Signs:
Tenderness over the chest wall
Palpable supraclavicular or cervical lymphadenopathy
Auscultation may reveal decreased breath sounds over the mass or stridor
Signs of SVC syndrome (facial plethora, engorged veins)
Cachexia in advanced disease
Neurological deficits.
Diagnostic Criteria:
No specific diagnostic criteria for the mass itself, but diagnosis is based on a combination of imaging, laboratory investigations, and histopathology
Clinical suspicion arises from symptoms or incidental findings
Imaging (CT, MRI) helps define location, size, and characteristics
Biopsy or resection confirms the diagnosis.
Diagnostic Approach
History Taking:
Detailed history of presenting symptoms, including onset, duration, and progression
Associated symptoms like fever, weight loss, or night sweats
Past medical history, including prior malignancies or genetic syndromes
Family history of tumors
History of infections
Review of systems to detect subtle symptoms.
Physical Examination:
Comprehensive head-to-neck examination, including lymph nodes
Thorough respiratory system examination, assessing for breath sounds, presence of wheezing or stridor
Cardiovascular examination
Neurological assessment for any focal deficits
Abdominal examination for hepatosplenomegaly.
Investigations:
Chest X-ray: Initial imaging to detect mediastinal widening or mass effect
CT scan of the chest: Gold standard for visualizing mediastinal anatomy, mass size, location, extent, and relationship to adjacent structures
MRI: Useful for evaluating neurogenic tumors, vascular involvement, and soft tissue characterization
Ultrasound: May be useful for superficial masses or guiding biopsy
Laboratory investigations: Complete blood count (CBC), electrolytes, renal and liver function tests
Tumor markers: Alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (β-hCG) for germ cell tumors
Lactate dehydrogenase (LDH) for lymphomas and germ cell tumors
Biopsy: Fine-needle aspiration (FNA), core needle biopsy, or incisional/excisional biopsy for histopathological diagnosis
Bronchoscopy and esophagoscopy: To assess airway and esophageal compression and for biopsy if indicated.
Differential Diagnosis:
Anterior mediastinal masses: Thymoma, germ cell tumors (teratoma, seminoma, non-seminoma), lymphoma (Hodgkin's and Non-Hodgkin's), thyroid masses, parathyroid adenoma
Middle mediastinal masses: Lymphadenopathy (infectious, inflammatory, malignant), bronchogenic cysts, pericardial cysts, vascular abnormalities
Posterior mediastinal masses: Neurogenic tumors (neuroblastoma, ganglioneuroma, schwannoma), esophageal duplications, neurenteric cysts, extramedullary hematopoiesis.
Management
Initial Management:
Airway assessment and management are paramount
Patients with significant airway compromise or SVC syndrome may require urgent intervention, including steroids, chemotherapy, or radiotherapy, prior to definitive surgery
Cardiopulmonary support may be necessary
Adequate intravenous access and fluid management.
Surgical Management:
Surgical resection is often the primary modality for diagnosis and treatment of benign and many malignant pediatric mediastinal masses
Indications include suspicion of malignancy, symptomatic masses, or masses causing significant compression
Techniques depend on the location and size of the mass: Median sternotomy: For anterior and some middle mediastinal masses
Posterolateral thoracotomy: For posterior and lateral masses
Video-assisted thoracoscopic surgery (VATS): Increasingly used for smaller, accessible lesions, offering minimally invasive benefits
Robotic-assisted surgery: Emerging as an option for complex resections
Complete resection is the goal
Careful dissection to preserve surrounding structures like the recurrent laryngeal nerve, phrenic nerve, and great vessels
Management of vascular involvement may require intraoperative collaboration with vascular surgeons or cardiologists.
Postoperative Care:
Close monitoring of respiratory status, vital signs, and fluid balance
Pain management
Chest tube management if placed
Early mobilization
Management of potential complications like pneumothorax, hemothorax, or infection
Nutritional support
In cases of malignancy, adjuvant therapy (chemotherapy, radiotherapy) will be planned based on histopathology and staging.
Supportive Care:
Respiratory physiotherapy
Adequate analgesia
Psychological support for the child and family
Monitoring for signs of infection or recurrence
Nutritional assessment and support
Management of any long-term sequelae.
Complications
Early Complications:
Bleeding and hematoma formation
Pneumothorax
Hemothorax
Chylothorax
Infection (wound infection, empyema)
Airway compromise post-extubation
Injury to adjacent structures (nerves, great vessels, esophagus)
Phrenic nerve palsy
Recurrent laryngeal nerve palsy
Anesthesia-related complications.
Late Complications:
Chronic pain
Adhesions
Pleural thickening
Recurrence of tumor
Radiation-induced long-term effects (if radiotherapy is used)
Development of secondary malignancies
Growth and developmental delays in pediatric patients.
Prevention Strategies:
Meticulous surgical technique to avoid iatrogenic injury
Careful preoperative assessment of airway and vascular structures
Use of minimally invasive techniques when appropriate
Prophylactic antibiotics
Effective pain control
Close postoperative monitoring
Adequate oncological follow-up.
Prognosis
Factors Affecting Prognosis:
Histological type of the mass (benign vs
malignant)
Grade of malignancy
Extent of resection (complete vs
incomplete)
Presence of metastasis
Patient's age and overall health status
Response to adjuvant therapy.
Outcomes:
Prognosis is generally excellent for benign mediastinal masses with complete surgical resection
For malignant masses, outcomes vary significantly depending on the specific tumor type and stage
Early diagnosis and treatment are associated with better outcomes
Long-term survival rates for pediatric lymphomas and germ cell tumors are improving with multimodal therapy.
Follow Up:
Regular clinical examinations and surveillance imaging (CT scans) are essential, especially for malignant masses, to detect recurrence or metastasis
The frequency and duration of follow-up are tailored to the specific diagnosis and treatment received
Survivors require long-term monitoring for late effects of treatment.
Key Points
Exam Focus:
The anatomical compartments of the mediastinum and common masses in each
The ABCD rule for anterior mediastinal masses (4 Ts: Thymoma, Teratoma/Germ cell tumor, Thyroid, Terrible lymphoma)
Clinical presentation of SVC syndrome
Indications for urgent intervention prior to resection
Differentiating benign from malignant features on imaging
Principles of surgical approach (sternotomy vs
thoracotomy vs
VATS).
Clinical Pearls:
Always consider airway management first in pediatric patients with mediastinal masses
SVC syndrome is a surgical emergency requiring prompt recognition and management
Use CT scan with contrast as the primary imaging modality
Tumor markers are crucial for germ cell tumors
Multidisciplinary team approach involving pediatric surgeons, oncologists, radiologists, and pathologists is vital
Complete resection is the goal for both diagnosis and cure.
Common Mistakes:
Delaying definitive diagnosis due to fear of biopsy in unstable patients
Inadequate preoperative imaging leading to surprises during surgery
Aggressive dissection of vascular structures without proper planning
Incomplete resection of malignant masses
Failure to consider oncological principles in the surgical plan for malignant tumors
Underestimating the risk of airway collapse postoperatively.