Clinical Presentation
All patients presented with rapidly enlarging neck masses, accompanied by symptoms such as dysphagia, hoarseness, and dyspnea, consistent with significant invasion of adjacent structures. Cervical lymphadenopathy was present in most cases, and distant metastases were evident in several patients at the time of diagnosis, underscoring ATC's aggressive and systemic nature.
Imaging Findings
- Ultrasound Ultrasound is often the first-line imaging modality for thyroid lesions due to its accessibility and effectiveness in real-time evaluation.
Primary Tumor Characteristics:
Ultrasound revealed large, irregular, and heterogeneous thyroid masses in all patients. Hypoechoic patterns, areas of internal necrosis, and microcalcifications were common features, with microcalcifications present in 70% of cases. These findings are consistent with the highly destructive behavior of ATC.
Soft Tissue Invasion and Lymphadenopathy:
Loss of tissue planes and evidence of vascular invasion were suggested in 60% of cases. Lymph nodes were characterized by rounded morphology, increased echogenicity, and the absence of fatty hilum, indicative of metastatic involvement.
- Computed Tomography (CT) Contrast-enhanced CT scans provided essential details about tumor size, morphology, and extension beyond the thyroid gland.
Tumor Morphology and Extension:
CT imaging demonstrated large, heterogeneous masses with poorly defined borders in all patients. Necrosis and calcifications were identified in 75% of cases, consistent with ATC's pathological profile.
Extrathyroidal Invasion:
Tumor extension into adjacent structures, including the trachea and esophagus, was evident in 50% of cases. This correlated with clinical symptoms such as airway obstruction and difficulty swallowing.
Vascular encasement, particularly involving the carotid arteries and internal jugular veins, was observed in 30% of patients. This invasion poses significant challenges for surgical intervention, as complete resection is often unfeasible.
Distant Metastases:
CT scans detected mediastinal lymphadenopathy and thoracic metastases in 25% of cases, further highlighting the disease's systemic nature.
- Magnetic Resonance Imaging (MRI)
While not routinely performed, MRI provided superior soft tissue contrast in cases where fine delineation of tumor invasion was critical.
Soft Tissue Involvement:
T1-weighted sequences highlighted hemorrhagic and necrotic areas within tumors, while T2-weighted imaging revealed edematous changes and inflammatory extensions. These findings helped to define the extent of muscle and laryngeal involvement.
Vascular Encroachment:
Gadolinium-enhanced MRI demonstrated subtle vascular encasement and confirmed findings from CT imaging.
- PET-CT Imaging
PET-CT was used primarily in advanced stages to evaluate metabolic activity and detect distant metastases.
Metabolic Activity:
PET-CT scans showed intense FDG uptake in both primary tumors and metastatic sites, reflecting the high metabolic activity of ATC. Lung, liver, and bone metastases were identified in 40% of patients.
Staging:
PET-CT findings allowed accurate staging of the disease, which is critical for tailoring therapeutic approaches.
Therapeutic Outcomes
Surgical Management
Complete surgical resection was achievable in fewer than 20% of patients due to extensive local invasion. When performed, total thyroidectomy with lymph node dissection provided local disease control but did not significantly alter overall survival due to systemic disease progression. In patients with unresectable tumors, debulking surgery was attempted to alleviate symptoms.
Radiotherapy
External beam radiotherapy, particularly intensity-modulated radiation therapy (IMRT), was employed in cases where surgical resection was incomplete or as a primary modality for unresectable tumors. Radiotherapy doses exceeding 40 Gy were associated with improved local control.
Chemotherapy
Chemotherapy with agents such as doxorubicin and paclitaxel was used, often in conjunction with radiotherapy. However, the efficacy of chemotherapy alone was limited, and its role remained largely adjunctive. Response rates were poor, consistent with ATC's intrinsic chemoresistance.
Targeted Therapy
In one patient with a BRAF V600E mutation, the combination of dabrafenib (a BRAF inhibitor) and trametinib (a MEK inhibitor) led to a complete response. The patient remained disease-free for 14 years, demonstrating the potential of precision therapies in select cases.
Prognostic Factors
Several imaging and clinical features correlated with outcomes:
Tumor Size: Larger tumors (>5 cm) were associated with poor prognosis.
Vascular Invasion: Imaging evidence of vascular encasement predicted unresectable disease and lower survival rates.
Distant Metastases: Patients with metastatic spread had a median survival of less than six months.