Endocrine Abstracts

Case: A 38-year-old HIV positive lady presented with a neck swelling and neutropenic sepsis. Examination of the neck revealed a firm diffuse non-tender goitre with cervical lymphadenopathy. She also had generalised lymphadenopathy, splenomegaly and miliary opacities in the lungs on the chest radiograph. Disseminated cryptococcal infection was diagnosed following isolation of the organism in blood and bone marrow. A radioisotope scan of the thyroid showed no uptake in the right lobe and reduced uptake in the left. Anti-thyroid microsomal antibodies were negative. She had hypothyroidism with a free T4 of 5.3 pmol/l (NR 11.5–23.2) and TSH 46 mU/l (NR 0.3–3.5), and was given thyroxine replacement. Histology from a core biopsy of the thyroid gland showed extensive replacement of thyroid tissue with organisms with a cell size considerably larger than an erythrocyte, surrounded by a halo effect. Cryptococcus was confirmed by Grocott silver stain.

Discussion: Both goitre and thyroiditis due to opportunistic infection have been described in patients with HIV infection. Cryptococcal infection presenting as hypothyroidism associated with goitre in a patient with HIV could be misdiagnosed as Hashimoto’s thyroiditis if infectious aetiologies are not considered. Thyroiditis in HIV may be due to suppurative thyroiditis (streptococcal or staphylococcal), Tuberculous thyroiditis, Pneumocystis carinii or Cryptococcal infection. A lymphocytic auto-immune thyroiditis has also been reported as a specific AIDS-related lesion. Thyroid function tests may be misleading in HIV because of rising thyroxine binding globulin, effects on the pituitary–thyroid axis due to hypermetabolism, and a sick euthyroid syndrome in the late stages of the disease, although free T3 concentrations are relatively well maintained in the early stages. We conclude that thyroid FNA and in some cases, core biopsy will have to be carried out in HIV patients with goitre and hypothyroidism to obtain an accurate diagnosis.