A 17-year-old girl notes an enlarging lump in her neck. On examination, her thyroid gland is twice the normal size, firm to rubbery, multilobular, nontender, and freely mobile. There is no adenopathy. Family history is positive for both hypo- and hyperthyroidism. Her serum triiodothyronine (T3) and thyroxine (T4) levels are low normal, and serum thyroid-stimulating hormone (TSH) is high normal. Technetium scan shows nonuniform uptake. Serum and antithyroglobulin titer is strongly positive.
What will thyroid biopsy of this patient most likely disclose?
- giant cell granulomas and necrosis
- polymorphonuclear cells and bacteria
- diffuse fibrous replacement
- lymphocytic infiltration
- parafollicular cells
Answer(s): D
Explanation:
The patient described in the question most likely has Hashimoto's thyroiditis, also called autoimmune or chronic lymphocytic thyroiditis. It is the most common cause of thyroiditis in the United States and is encountered more frequently in women than in men. Patients note progressive thyromegaly but are usually euthyroid at the outset. Hypothyroidism may appear years later, often heralded by an elevated serum TSH level. Diagnosis is based on the history, examination, heterogeneous uptake on thyroid scan, and the presence of antithyroid and antithyroglobulin antibodies. If the diagnosis is still in doubt, needle biopsy will demonstrate lymphocyte infiltration, sometimes in sheets or forming germinal centers. Subacute (de Quervain, granulomatous) thyroiditis will show polymorphonuclear cells, necrosis, and giant cells. Bacteria may not be present in acute suppurative thyroiditis. Thyroid infiltration and replacement by rock-hard, woody, fibrous tissue is typical of Riedel's struma. C-cell hyperplasia is associated with medullary thyroid carcinoma. Hashimoto's thyroiditis is treated with thyroid hormone. Lower doses (0.100.15 mg/day) of levothyroxine are used to treat hypothyroidism alone; whereas, higher doses (0.150.30 mg/day) suppress TSH release and diminish goiter size. Partial resection may result in enlargement of the remaining gland.
Steroids, antibiotics, and radioiodine have no role in therapy.