As an initiative of our current president, Professor Shiro Noguchi, the IAES has introduced a special question-site for medical personnel, concerning endocrine surgery, and in which answers to questions will be provided by specially selected IAES members. In this section we hope to be able to present interesting questions, and possibly discussions, which will help to further develop and increase knowledge about the management of endocrine surgical diseases. Anyone, general surgeons or IAES members are free to send questions to the Secretary-Treasurer:
Professor Gerard M Doherty
University of Michigan
Department of Surgery
2920 Taubman Health Care Center
1500 East Medical Center Drive
Ann Arbor, MI 48109
USA
Fax: +1-734-936-5830
Questions should be sent by e-mail, fax or ordinary letter. When you send a question, please give your name, occupation, speciality, address, together with a brief patient history with relevant test results, and ask your specific questions.
Below you can see examples how these Questions and Answers may appear. The names in these examples are invented.
Example 1
Name: John Mann, obstetrician, 25th Street, Manhattan, New York, N.Y., USA.
The patient is a 34-year old woman, pregnant in the 25th week, who 3 years ago underwent subtotal thyroidectomy for thyreotoxicosis. She is now euthyroid, without medication, but still has significantly raised thyroid stimulating immunoglobulines.
Questions:
1. Is there any possibility that she may bear a neonatal hyperthyroid baby?
2. If so, how high is the probability?
3. What kind of precaution is necessary?
Answers:
- It is possible that the patient might bear a hyperthyroid baby.
- Several case reports have been presented, but there is no statistical study of probability.
- Measurement of free T4 and TSH in umbilical blood is recommended in order to know the thyroid status of the baby.
Comment by expert:
The patient is euthyroid without medication, ie has a thyroid remnant producing thyroid hormones. In a case like this, the woman might have anti-TSH receptor antibodies in the circulation, antibodies that stimulate her thyroid and contribute to her ability to maintain an euthyroid state without supplementary thyroxine.
Transplacental passage of maternal IgG takes place during a normal pregnancy and becomes significant in the third trimester. Passage of TSH-receptor antibodies will affect the fetal thyroid with a risk of thyrotoxicosis. The likelihood of thyrotoxicosis depends on the antibody titer (determined by radioimmunoassay; an assay that does not demonstrate the biological activity) and the biological activity of the antibodies (in a case of Graves disease the antibodies are typically stimulatory). If TSH-receptor antibodies are present in high titers, the fetus will develop intrauterine thyrotoxicosis, if the titers are in the low-middle range, there still is a considerable risk of fetal thyrotoxicosis, and if the titer is low or barely detectable, the risk of thyrotoxicosis is small. A diagnosis of fetal thyrotoxicosis is made when the fetal heart rate is above 160 beats per min, often there is also lively fetal movements. Treatment of the mother should be given with thyrostatic drugs, in this case methimazol or propylthiouracil could be used in the lowest dose able to normalize the fetal heart rate. Treatment should be instituted in collaboration with an endocrinologist.
At delivery, the cord blood should be tested for free thyroxine, TSH and TSH-receptor antibodies. If the antibody titers are elevated, there is a risk for neonatal thyrotoxicosis. This develops within 1-2 days (the delay being due to decay of the thyrostatic drug that the fetus received via the mother). If neonatal thyrotoxicosis appears, treatment is given with methimazole in collaboration with a pediatrician.
Anders Karlsson, MD
Professor of Endocrinology
Department of Medicine
University Hospital
SE-751 85 Uppsala, Sweden
Example 2
Name: Taro Yamamoto, general practitioner, 3-5 Sakaemachi, Maebashi, Gunma, Japan.
The patient is a 51-year old carpenter, who has noticed a lump in the neck. The lump is hard, measures 3 x 2.5 cm, and moves with the larynx during swallowing and is thus likely to represent a thyroid tumor.
Questions:
- What diagnostic investigations are suggested that can help decide whether this thyroid tumor is benign or malignant?
- How precise are the tests?
Answers:
- Fine needle aspiration cytology is presently the best method to preoperatively determine whether a thyroid tumor is benign or malignant.
Ultrasonography may be an important aid which may be used to differentiate solid tumors, cystic tumors, and solid tumors with a cystic portion. Solid tumors without halo, with irregular margin, slightly hypoechogenic, and with multiple small hyperechogenic spots, are more likely to represent papillary cancer. Cystic tumors without a solid portion are usually benign. Solid tumors with a cystic portion are most likely benign, if the cystic portion is close to the center of the tumor. When the cystic portion is within peripheral parts of the tumor, the possibility of malignancy is higher.
- The precision of fine needle aspiration cytology may vary between centres, but is generally about 85%. In follicular cancer, Hürthle cell cancer, and rare follicular variants of papillary cancer, it may not be possible to determine with cytology whether the lesion is benign or malignant.
The precision of ultrasonography is highly dependent on the experience of the investigator, the instruments used, and the size of the tumor. Well experienced ultrasonographers claim they may reveal benign or malignant features in nearly 80% of lesions, but still the ultrasonic diagnosis always remains more equivocal than cytology.
Comment by expert:
Ultrasound of the thyroid gland
Since the first report in 1966 more than 1000 publications have been produced about thyroid ultrasound (US). The rapid advances in technology allow real-time imaging and visualisation of minute morphological changes in the thyroid. With the addition of Colour-flow Doppler the vasculature and blood flow of the thyroid gland can be demonstrated. The most commonly used 7.5-10 MHz probe gives excellent visualisation of the thyroid gland and other neck tissues. It gives an estimate of tissue density (echogenicity), as well as vascular flow and neck lymph glands. The thyroid size and volume can be calculated. Still the debate of the role of US in the management of thyroid disorders is justified. Although the investigation is relatively cheap and fast, observer variation exists and the interpretation of the findings are very much dependant on the experience of the investigator.
The thyroid size and volume have been used in screening purposes to determine the goitre incidence in regions of iodine deficiency and for calculation of ablative radioactive doses. For patients with local discomfort from the neck who are difficult to palpate for anatomical reasons or when the clinical palpation is uncertain, US may be useful to ascertain whether symptoms are likely to originate from the thyroid.
The echogenicity of the thyroid gland may be altered in a number of conditions. Diffuse hypoechogenicity exists in autoimmune thyroiditis; subacute thyroiditis and Graves´ disease, and this finding may, in combination with laboratory findings, be of value in occasional patients. The differential diagnosis in toxic TSH-receptor antibody negative patients suffering from either Graves´ disease or multinodular goitre may be clarified by ultrasound.
The clinical evaluation of a solitary nodule can be difficult and considerable observer variation exists. In this context US may be of help to establish the existence of a single tumour, or if the patient has multinodular goitre with involvement of the contralateral lobe. This may be used to plan the surgical procedure in patients with multiple nodular goitre.
Much effort has been put into characterisation of the solitary nodule in order to define US criteria for suspicion of malignancy. Although no single sonographic criterion is specific for malignancy several have been indicative for papillary thyroid carcinoma, such as hypoechogenic tumours with ill defined margins containing calcifications or the classical cauliflower appearance within a partly cystic lesion. The presence of pathologically enlarged lymph nodes may also increase the suspicion of papillary carcinoma. Both micro- and macro-follicular adenomas are often surrounded by a halo, but are indistinguishable from each other and from follicular carcinomas. Ultrasound cannot substitute fine needle aspiration biopsy (FNAB), but may help to select patients for this biopsy. In case of non-diagnostic FNAB ultrasound-guided FNAB may be of value. US may also be used in the follow-up of patients subjected to total thyroidectomy for papillary carcinoma, to reveal locally recurrent disease when s-thyroglobulin concentrations rise. In centres that perform hemithyroidectomy for papillary carcinoma US may be used to check the remnant lobe for recurrent disease.
True thyroid cysts are uncommon and may be diagnosed with US and treated with US-guided aspiration and injection with ethanol.
In the future, if used judicious, US of the thyroid gland will function as a complement to the history, physical examination, laboratory work-up and and FNAB for investigation of thyroid disorders. A surgeon may be trained to become an excellent US investigator.
Claes Juhlin, MD
Associate Professor
Chief of Clinic
Department of Surgery
University Hospital
SE-581 85 Linköping, Sweden