SSTR 5 was shown to be the main receptor subtype in the analysed differentiated or anaplastic thyroid malignancies, whereas SSTR 2 was found only in a small percentage. Deficient SSTR expression may indicate higher risk for persistent or recurrent disease after initial therapy. For this reason immunohistochemistry can be considered a prognostic marker which should be further validated in prospective studies.

We report on a 71-year-old woman presenting with biochemical features indicating recurrent disease in long-term follow-up of left-sided parathyroid carcinoma. She had undergone several surgical procedures including total thyroidectomy, partial resection of the esophageal wall, and curative neck radiation 12 years previously. PET/CT using F-fluorocholine revealed high uptake in local relapse in the lower neck, comparable to F-FDG, whereas only faint uptake was observed with F-fluoroethyl tyrosine. As shown in this case, imaging with FDG and F-fluorocholine is feasible in (recurrent) parathyroid carcinoma and clearly superior to F-fluoroethyl tyrosine.

Differentiation between granulomatous inflammation and malignancy is challenging with ¹⁸F-FDG-PET/CT because of a large number of false-positive findings. The highest probability of detecting coexistent malignant disease was seen in patients older than 60 years who were suffering from tuberculosis. An important feature for identification of malignant disease, especially in the assessment of intrathoracic findings, has turned out to be the CT pattern; quantitative evaluation, in contrast, seems to have little clinical value.

In the examined group of patients, the prevalence of abnormal thyroidal parameters was 23 %. Decreased fT4, which does not require therapy, was observed most frequently (12 %) and correlated with PI use. On the other hand, elevated bTSH (6 %) correlated with ART duration and NRTI use. In mild subclinical hypothyroidism as observed in this patient population, thyroxine medication is not indicated in principle. Annual TSH screening is probably sufficient in HIV-infected patients with no clinical symptoms suggestive for thyroid disease.

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