Sarcoma of the thyroid region mimicking Riedel's thyroiditis

Area of Science:

• Oncology
• Pathology
• Endocrinology

Background:

• Anterior lower neck sarcomas are rare and often overlooked in differential diagnoses.
• Riedel's thyroiditis can mimic malignant neoplasms due to its invasive nature.
• Sarcomatoid carcinoma is a key differential diagnosis to exclude.

Observation:

• A patient presented with a suspected anterior lower neck mass.
• Initial clinical and radiological assessments suggested Riedel's thyroiditis or sarcomatoid carcinoma.
• Peroperative biopsy was interpreted as Riedel's thyroiditis by two pathologists.

Findings:

• Postmortem examination confirmed a high-grade sarcoma with extensive metastasis.
• The sarcoma invaded adjacent neck structures and metastasized to the lungs and pleura.
• Some areas showed microscopic features resembling mediastinal fibrosis, suggesting potential malignant transformation.

Implications:

• This case underscores the need to include rare sarcomas in the differential diagnosis of anterior lower neck masses.
• Histological examination is crucial for differentiating sarcomas from Riedel's thyroiditis and sarcomatoid carcinoma.
• The findings suggest a possible link between fibrosclerotic lesions and sarcoma development.