P1-715

ELASTOGRAPHIC EVALUATION OF THYROID NODULES IN ACROMEGALYELASTOGRAPHIC EVALUATION OF THYROID NODULES IN ACROMEGALY

M. Andrioli ¹, C. Carzaniga ¹, M. Scacchi ¹, G. Vitale ¹, M. Moro ¹, L. Poggi ², L. Fatti ¹ and F. Cavagnini ¹¹ Chair of Endocrinology, University of Milan, Ospedale San Luca, IRCCS, Istituto Auxologico Italiano, Milan, Italy

² General Surgery, First Unit, Fondazione Ospedale Maggiore Policlinico e Regina Elena, IRCCS, Milan, Italy

Background Ultrasound-elastography (US-E), a new ultrasonographic technique used to provide an estimation of tissue stiffness, appears to be a helpful tool for the diagnosis of thyroid cancer (1,2). In acromegaly, multinodular goiter is a common occurrence, while the prevalence of thyroid cancer is still a matter of debate (3).

Results and Discussion Fourteen out of 90 nodules (15.5%) displayed an ES value of 1, 25 (27.7%) an ES value of 2, 37 (41.3%) an ES value of 3 and 14 (15.5%) an ES value of 4 (Figure 2). The prevalence of hard nodules (ES 3-4) in patients with active acromegaly (68.9%) was greater, though not to a statistically significant extent, than that observed in cured (44.4%) and controlled (52.5%) patients (Table 1). In the whole series of patients, the prevalence of hard nodules (56.7%) appeared greater than that reported in non acromegalic subjects bearing thyroid nodular disease including cancer (33.7%) (2,4). All thyroid nodules undergone FNAC were negative for malignant cells or for follicular lesion and, according with this result, the vast majority of hard lesions did not display US features suggesting malignancy (Figure 3) with the exception of hypoechogenicity, which seems to be a typical feature of nodular fibrosis (5). It is conceivable that fibrosis is responsible for the hard US-E pattern of so many nodules in acromegaly (6).

Aims of the study were to evaluate thyroid nodules in acromegaly and to establish the accuracy of US-E in providing information on their nature, using cytological analysis as a reference.

Patients and methods A total of 35 acromegalic patients were studied by conventional ultrasonography (US) and color-power-Doppler-ultrasonography. US-E was performed in 25 of these patients (7 cured by pituitary surgery, another 8 controlled by medical therapy and the remaining 10 with active disease), presenting at least one solid thyroid nodule. All 90 solid nodules detected were classified according to the elastographic scores (ES) in four classes of hardness: ES 1 and 2 was assigned to soft nodules; ES 3 and 4 to hard lesions (4) (Figure 1). FNAC could be performed in 60.8% of the nodules with ES suspect for malignancy, namely 78.6% of ES 4 lesions and 54.1% of ES 3 nodules.

Conclusions This study has demonstrated a high prevalence of stiff thyroid nodules in acromegaly, especially in patients with active disease. This prevalence is higher than that found in non acromegalic subjects with thyroid nodular disease. These nodules, however, have proved not to be malignant at cytology and are probably of fibrous nature. Thus, US-E appears to be of limited value for the diagnosis of thyroid cancer in acromegaly.

A B

C D

Figure 1. ES 1 was assigned to nodules presenting elasticity in the whole examined area, ES 2 to nodules displaying elasticity in a large portion of the examined area, ES 3 to nodules with stiffness in a large portion of the examined area, ES 4 to anelastic nodules. (Modified from Asteria, Thyroid 2008)

Figure 2. Conventional ultrasonographic and elastographic features of thyroid nodules in acromegalic patients. According to the previously mentioned criteria, the lesions have been assigned ES 1 (panel A), ES 2 (panel B), ES 3 (panel C) and ES 4 (panel D).

Figure 3. Prevalence of the main conventional ultrasonographic features suggesting malignancy among ES 3 and ES 4 nodules. HYP: hypoecogenicity; INH: inhomogeneity; IRR: irregular margins; INT: intralesional vascularization; MIC: microcalcifications.

US features of ES3 nodules

0%

20%

40%

60%

80%

100%

HYP INH IRR INT MIC

US features of ES4 nodules

HYP INH IRR INT MICHYP INH IRR INT MIC

yes

no

yes

no

yes

no

0%

20%

40%

60%

80%

100%

0%

20%

40%

60%

80%

100%

Absolute number of nodules and, in brackets, percent values are shown.

ES 3 -4ES 1 -2ES 4ES 3ES 2ES 1

22 (68.9)

21 (52.5)

8 (44.4)

10 (31.1)

19 (47.5)

10 (55.6)

6 (18.9)

5 (12.5)

3 (16.7)

16 (50.0)

16 (40.0)

5 (27.7)

7 (21.8)

15 (37.5)

4 (22.3)

3 (9.3)Active

4 (10.0)

6 (33.3)

Controlled

Cured

ES 3 -4ES 1 -2ES 4ES 3ES 2ES 1

22 (68.9)

21 (52.5)

8 (44.4)

10 (31.1)

19 (47.5)

10 (55.6)

6 (18.9)

5 (12.5)

3 (16.7)

16 (50.0)

16 (40.0)

5 (27.7)

7 (21.8)

15 (37.5)

4 (22.3)

3 (9.3)Active

4 (10.0)

6 (33.3)

Controlled

Cured

22 (68.9)

21 (52.5)

8 (44.4)

10 (31.1)

19 (47.5)

10 (55.6)

6 (18.9)

5 (12.5)

3 (16.7)

16 (50.0)

16 (40.0)

5 (27.7)

7 (21.8)

15 (37.5)

4 (22.3)

3 (9.3)Active

4 (10.0)

6 (33.3)

Controlled

Cured

Table 1. Prevalence of the different ES according to the activity of acromegaly.

References1) Lyshchik A, Higashi T, Asato R, Tanaka S, Ito J, Mai JJ, Pellot-Barakat C, Insana MF, Brill AB, Saga T, Hiraoka M, Togashi K 2005 Thyroid gland tumor diagnosis at US elastography. Radiology 237:202–2112) Rago T, Santini F, Scutari M, Pinchera A, Vitti P 2007 Elastography: new developments in ultrasound for predicting malignancy in thyroid nodules. J Clin Endocrinol Metab 92:2917-29223) Colao A, Ferone D, Marzullo P, Lombardi G 2004 Systemic complications of acromegaly: epidemiology, pathogenesis, and management. Endocr Rev 25:102-1524) Asteria C, Giovanardi A, Pizzocaro A, Cozzaglio L, Morabito A, Somalvico F, Zoppo A 2008 US-Elastography in the Differential Diagnosis of Benign and Malignant Thyroid Nodules. Thyroid 18:523-5315) Chen SJ, Yu SN, Tzeng JE, Chen YT, Chang KY, Cheng KS, Hsiao FT & Wei CK. Characterization of the major histopathological components of thyroid nodules using sonographic textural features for clinical diagnosis and management. Ultrasound in Medicine & Biology 2009 35 201-208.6) Dighe M, Bae U, Richardson ML, Dubinsky TJ, Minoshima S, Kim Y 2008 Differential diagnosis of thyroid nodules with US elastography using carotid artery pulsation. Radiology 248:662-669