The use of fine-needle aspiration biopsy under ultrasound guidance to assess the risk of malignancy in patients with a multinodular goiter

Management of simple nodular goiter: current status and future perspectives

The simple nodular goiter, the etiology of which is multifactorial, encompasses the spectrum from the incidental asymptomatic small solitary nodule to the large intrathoracic goiter, causing pressure symptoms as well as cosmetic complaints. Its management is still the cause of considerable controversy. The mainstay in the diagnostic evaluation is related to functional and morphological characterization with serum TSH and (some kind of) imaging. Because malignancy is just as common in patients with a multinodular goiter as patients with a solitary nodule, we support the increasing use of fine-needle aspiration biopsy (cytology). Most patients need no treatment after malignancy is ruled out. In case of cosmetic or pressure symptoms, the choice in multinodular goiter stands between surgery, which is still the first choice, and radioiodine if uptake is adequate. In addition to surgery, the solitary nodule, whether hot or cold, can be treated with percutaneous ethanol injection therapy. If hot, radioiodine is the therapy of choice. Randomized studies are scarce, and the side effects of nonsurgical therapy are coming into focus. Therefore, the use of the optimum option in the individual patient cannot at present be based on evidence. However, we are of the view that levothyroxine, although widely used, should no longer be recommended routinely for this condition. Within a few years, the introduction of recombinant human TSH and laser therapy may profoundly alter the nonsurgical treatment of simple nodular goiter.

Multinodular goiter

MNG is a common clinical problem. Though most goiters are benign and asymptomatic, they may cause concern when they create compressive symptoms, develop autonomous functioning nodules, or form suspicious nodules. Diagnostic evaluation should include clinical evaluation, laboratory tests including TSH, and consideration of additional evaluation and imaging when there exists suspicion of complicating factors or risk of malignancy. In nontoxic MNG, suppression therapy or serial clinical exams and TSH values are appropriate in an asymptomatic, nonsuspicious goiter. In toxic MNG, treatment of the resulting thyrotoxicosis followed by RAI or surgery is indicated. When compressive symptoms, risk of malignancy, or cosmetic deformity develops, surgery also may be indicated.

Absence of histological malignancy in a patient cohort with follicular lesions on fine-needle aspiration

Follicular lesions account for 4-6% of all thyroid fine-needle aspiration (FNA) cytologies. To date, no cytological criteria exist to distinguish follicular adenoma from carcinoma. For this purpose, histological evaluation after surgical exeresis is required. From 1993 to 2000 we performed 1,238 US-assisted FNA biopsies in patients admitted to our unit for uni- or multi-nodular goiters. In the latter goiters, FNA was performed in the dominant nodule. Cytological examination revealed a follicular lesion in 71 patients (5.7%). All patients came from regions of Northern Italy with moderate iodine deficiency. In 48%, the lesion presented as a solitary nodule, while in the other 52% it occurred in the context of a multinodular goiter. Surgical exeresis of the neoplasm was recommended in all cases. Sixty-three patients (89%) underwent surgery (Group 1) while the other 8 patients (11%) opted for follow-up (Group 2). In Group 2, the mean nodule volume (3.2 +/- 0.5 ml) at baseline was slightly smaller (p = 0.08) than that found in Group 1 (5.4 +/- 0.7 ml). In Group 1, histological examination after surgery showed a follicular adenoma in 52 patients (83%) and a colloid goiter in the others (17%). No malignancy was detected. Group 2 underwent a median follow-up of 46 months (range 24-96 months) on L-thyroxine suppressive regimen (dose range 75-125 pg/day), with TSH levels ranging from 0.1 to 0.3 mlU/l. Throughout the follow-up, no patient developed clinical or ultrasonographic features that could be considered worrisome for malignancy; thus, no further biopsy was performed. However, an overall slight increase (median +5.2%) in nodular volume in respect to baseline was observed. Although institutional and cytological bias cannot be ruled out, our data do not confirm the reported incidence of malignancy in histological specimens of follicular lesions diagnosed on FNA cytology, and prompt us to suggest a less aggressive first-step approach (i.e. careful clinical and instrumental evaluation, and suppressive L-T4 therapy) for these lesions, unless anamnestic reports or clinical and ultrasonographic features of the nodules suggest malignancy.

Fine-needle aspiration biopsy of the thyroid: comparison between thyroid palpation and ultrasonography

OBJECTIVE

To describe our experience with fine-needle aspiration biopsy (FNAB) of the thyroid and compare our results with direct palpation versus ultrasound scanning (USS) in an area of endemic goiter in Italy.

METHODS

We considered all patients submitted to ultrasound-guided FNAB of thyroid nodules during a 10-month period at our outpatient clinic and analyzed the following: (1) clinical data (number of nodules and identification of the nodule for FNAB); (2) USS data (number of nodules and identification of the nodule for FNAB on the basis of hypoechoic pattern + blurred perinodal halo + microcalcifications or intranodal color Doppler signal indicative of blood flow); (3) cytologic specimens, categorized as suspicious, malignant, negative, or nondiagnostic; and (4) histologic final report of the cytologically positive nodules.

RESULTS

The study group consisted of 348 female and 72 male patients who underwent FNAB of the thyroid at our institution. Among the 140 patients with no palpable thyroid nodules, USS showed that 106 had a single nodule and 34 had multinodular goiters. Among the 182 patients with a single palpable thyroid nodule, USS revealed that 138 had a single nodule, 42 had a multinodular goiter, and 2 had lobe enlargement without detectable nodules. All 98 patients with multinodular palpable goiter had a similar pattern on USS. Of the 420 cytologic specimens, 46(11.0%) were positive for thyroid cancer, 313 (74.5%)were negative, and 61 (14.5%) were nondiagnostic. Histologic malignant growth was confirmed in 27 cytologically positive nodules. Of these histologically malignant nodules, 12 (45%) were nonpalpable, 9 (33%) were single palpable nodules, and 6 (22%) were from a nodule with a suspicious ultrasound pattern within a multinodular goiter.

CONCLUSION

Manually guided FNAB is not feasible in nonpalpable nodules and not accurate in a multinodular goiter. Both situations are clinical challenges, and USS should be performed for accurate FNAB under these circumstances. Because 52% of histologically malignant nodules in our study were found only with the aid of ultrasound-guided FNAB, this procedure should be used where multinodular goiter is endemic. Our overall rate of nondiagnostic specimens was comparable to that reported in the literature.

Thyroid ultrasound

Evaluation of the thyroid gland can be performed by several imaging techniques. Although ultrasound (US) lacks specificity for tissue diagnosis and can rarely distinguish benign from malignant disease, it can distinguish solid nodules from simple and complex cysts. It allows accurate estimation of thyroid size, gives a rough estimate of tissue density (echogenicity), shows vascular flow and velocity (color-flow Doppler), can identify regional lymphadenopathy, and aids in the accurate placing of needles for diagnostic or therapeutic purposes. In addition, it is widely available, relatively rapid and cheap, visualizes the whole anterior neck, and does not involve ionizing irradiation. This article aims at clarifying the role of US in clinical thyroidology by pointing to areas where the technology can aid in clinical decision making. It is argued that more clinician endocrinologists should master and use this technology for diagnostic and therapeutic purposes.

Thyroid nodules: pathogenesis, diagnosis and treatment

Thyroid nodules are very frequently found and their prevalence steadily increases with age. The discovery of such lesions by high-resolution radiological imaging procedures that have been performed for other indications raises the problem of how incidentally discovered thyroid nodules should be investigated in a cost-effective manner to identify the rare patient with a clinically significant malignancy. In this review the clinical criteria that prompt the evaluation of thyroid nodules are discussed, as is the currently recommended diagnostic approach, which principally relies on fine needle aspiration biopsy. The clinical implications of the different cytological diagnoses are discussed, with a special emphasis on the management of indeterminate, microfollicular lesions. Finally, the evidence for and against suppressive thyroid hormone therapy for benign thyroid nodules and multinodular goitres is discussed, with particular consideration of high-risk patients with prior external radiation therapy to the neck region.

Surgical approach to thyroid nodules and cancer

Fine needle aspiration cytology is the mainstay of the diagnostic work-up of solitary thyroid nodules. Together with the patient's history and the clinical findings, cytology determines the indication for surgery. The minimal intervention for a suspicious nodule consists of thyroid lobectomy. If a diagnosis of malignancy is established, then we recommend total thyroidectomy for all follicular lesions that are larger than 1.5 cm and for high-risk papillary tumours. Near-total thyroidectomy may be appropriate for low-risk patients with papillary carcinoma in whom it is not intended to use radioactive iodine ablation. Whereas ipsilateral lymphadenectomy of the central (primary) compartment should routinely be performed, modified radical neck dissection is only indicated in evident nodal disease of the lateral (secondary) compartment(s). Patients with incidentally discovered differentiated thyroid carcinomas generally do not require complete thyroidectomy unless the tumours are larger than 1.5 cm in diameter or nodal involvement is present. A detailed description of the surgical technique for thyroidectomy and lymphadenectomy is given and an overview of surgical complications is provided.