All of the following are true about Lymphoma of the thyroid except:
Lymphoma of the thyroid is a rapidly growing malignancy similar to anaplastic carcinoma. Sabiston writes - "This diagnosis should be considered in patients who present with a goitre, especially one that has apparently grown significantly in a short period."
Lymphoma

Lymphoma is a rare malignancy of thyroid (< 1%).
Most are of non-Hodgkin's B-cell type.
Although the disease can arise as part of a generalized lymphomatous condition, most thyroid lymphomas develop in patients with chronic lymphocytic thyroiditis (Hashimoto's ds.)
Presenting symptoms are :

- rapidly enlarging mass (similar to anaplastic ca but is often painless.)
- acute respiratory distress
- hoarseness
- dysphagia
- fever

Diagnosis is usually suggested by FNA biopsy, although core needle or open biopsy may be necessary for definitive diagnosis.

Treatment
- Thyroid lymphoma responds rapidly to chemotherapy (CHOP - cyclophosphamide, doxorubicin, vincristine and prednisone)
- Combined t/t with radiotherapy & chemotherapy is recommended.
- Surgical resection is recommended to alleviate pressure symptoms.
More common in females
Slow growing
Clinically confused with undifferentiated tumours
May present with respiratory distress and dysphagia