The shape of the nodule - Table 2 (large) Deceptive patterns

In contrast with other suspicious characteristics, in the event of nonparallel orientation (NPO) we face with much less differential diagnostic problems. Such issues can be caused by anatomical situations or pathological conditions.
The former is encountered in lobes presenting nonparallel orientation. The shape of the thyroid is narrowed at the upper and lower pole, which means that in this position, it is more difficult to spread a benign nodule into the usual medial or lateral direction, therefore even benign nodules in the upper or lower third of the lobe show more frequently nonparallel orientation. The normal sideway growth can be hindered in nodules which are sandwiched between the trachea and the carotid artery.
We meet pathological conditions causing NPO in macrocalcifications or dominantly cystic nodules. Another problem arises in multinodular goiters when a neighboring nodule hinders the spread into the medial-lateral or upper-lower direction. The issue of thyroiditis is the usual: suspicious characteristics are interpreted in the context of pathological nodules, so a more active foci of thyroiditis presenting taller-than-wide or taller-than-long shape should not be overestimated.

Benign nodular goiter (cytology) - case 2116

Transverse scan

Longitudinal scan

This nodular area presents nonparallel orientation in the upper right image which shows the lower part of the nodule. In this location the thyroid is normally narrowed, and the ratio of width to depth of the normal gland is usually < 1. Therefore, a nodule located in the lower pole can present non-parallel orientation simply because it follows the shape of the lobe. It is worth viewing the video.

 

Benign lesion - case 2178

The small nodule shows irregular shape, but this is not of pathological importance. The hard wall of the carotid artery prevents the nodule from spreading sideways.

   
Hashimoto's thyroiditis (histology) - case 1096

The lesion in the dorsal part of the lobe shows taller-than-wide shape. However, this is not a pathological form of nonparallel orientation. The taller-than-wide sign is caused by the anatomy, the trachea and the carotid artery hinder the growth of the lesion sideways. Moreover, the lesion proved to be not a true nodule on histopathology.

   
Benign lesion (cytology) - case 1370
Right lobe, transverse scan
Left lobe, transverse scan

Both lobes present taller-than-wide shape. In such lobes a nodule simply follows the shape of the lobe.

   
Follicular tumor (cytology) - case 2051
Upper part of the right lobe, transverse scan
Middle-lower part of the right lobe, transverse scan

The upper nodule shows taller-than-wide shape similarly to that part of the lobe, while the nodule in the lower two-third of the lobe does regular, parallel orientation.

   
Benign nodular goiter (cytology) - case 2016

The nodule shows taller-than-long shape. However, the nonparallel orientation is caused by the anatomical situation: the lesion was sandwiched between two other nodules. The latter are signed with yellow arrows.

   

Benign nodular goiter (cytology) - case 2115

Four images gained on longitudinal scan are presented. The issue is the same as in the previous case: is it a discrete area composed of a single or multiple nodules. In my opinion, it is rather a single nodule: we can see on the left lower image an irregularly shaped echonormal area, the tail of which can be found even in the hypoechogenic part of the lesion.

   
Benign nodular goiter (cytology) - case 2121
Upper part of the right lobe, transverse scan
Middle-lower part of the right lobe, transverse scan

Upper part of the right lobe, longitudinal scan

Lower part of the right lobe, longitudinal scan

The shape of the small hypoechoic nodule is close to taller-than-wide in transverse scan (right upper image) while clearly shows taller-than-long shape on longitudinal sections (right lower image). However, the latter is caused by the large nodule which hinders the normal growth in the upway direction.

   
Benign lesion (cytology)
Papillary cancer (histology) - conp 057
Transverse scan

Longitudinal scan

Although at first sight, the nodule seems to show taller-than-wide shape and both taller-than-wide and taller-than-long shape, left and right case, respectively. Indeed, the acoustic shadow caused by the macrocalcification makes the judgement of the nodule' depth impossible.

   
Subacute, de Quervain's thyroiditis (cytology) - case 2125
Subacute, de Quervain's thyroiditis (cytology) - case 2129
Transverse scan

Longitudinal scan

In the event of thyroiditis, the matter is not the presence of nonparallel orientation but the presence of pathological nodule. The discrete lesions in these cases show taller-than-wide sign, however, they are not pathological nodules but more active foci of the underlying thyroiditis.
   
Hashimoto's thyroiditis - case 2122
Papillary cancer in Hashimoto's thyroiditis - case conp 043
Transverse scan

Longitudinal scan

The largest hypoechoic lesions present both taller-than-wide and taller-than-long shape in both cases. The presentations of these cases are practically identical. In the event of thyroiditis, the matter is not the presence of nonparallel orientation but the presence of pathological nodule.
   
Benign lesion (cytology) - case 2086
Transverse scan
Longitudinal scan

This pure cyst shows taller-than-wide sign, however, in the event of pure cysts, the nonparallel orientation has no relevance.
   
Benign lesion (cytology) - case 956
Transverse view
Longitudinal view

Transverse view after aspiration of cystic content

Longitudinal view after aspiration of cystic content

The seemingly cystic nodule showed taller-than-wide shape before aspiration. After the aspiration, the shape became parallel and it turned out that the nodule was not a completely cystic one.

 
   
Subacute, de Quervain's thyroiditis (cytology) - case 2125
Subacute, de Quervain's thyroiditis (cytology) - case 2129
Transverse scan

Longitudinal scan

In the event of thyroiditis, the matter is not the presence of nonparallel orientation but the presence of pathological nodule. The discrete lesions in these cases show taller-than-wide sign, however, they are not pathological nodules but more active foci of the underlying thyroiditis.
   
Hashimoto's thyroiditis - case 2122
Papillary cancer in Hashimoto's thyroiditis - case conp 043
Transverse scan

Longitudinal scan

The largest hypoechoic lesions present both taller-than-wide and taller-than-long shape in both cases. The presentations of these cases are practically identical. In the event of thyroiditis, the matter is not the presence of nonparallel orientation but the presence of pathological nodule.
   
Benign lesion (cytology) - case 2086
Transverse scan
Longitudinal scan

This pure cyst shows taller-than-wide sign, however, in the event of pure cysts, the nonparallel orientation has no relevance.
   
Benign lesion (cytology) - case 956
Transverse view
Longitudinal view

Transverse view after aspiration of cystic content

Longitudinal view after aspiration of cystic content

The seemingly cystic nodule showed taller-than-wide shape before aspiration. After the aspiration, the shape became parallel and it turned out that the nodule was not a completely cystic one.