Subisthmic accessory thyroid gland in man: a case report and a review of thyroid anomalies

Ultrasonographic study of the incidence of pyramidal lobe and agenesis of the thyroid isthmus in Nnewi population

Introduction: Ultrasound is the most reliable imaging modality for thyroid evaluation due to the limitations in the clinical examination of this gland. Thyroid gland developmental anomalies are rare. Most of its variations are due to the persistence of the thyroglossal duct and the absence of the isthmus. The aim of this study was to determine the incidence of pyramidal lobe and agenesis of the thyroid isthmus in Nnewi population using ultrasound. Materials and method: A total of 321 subjects resident in Nnewi, including 167 males and 154 females, were randomized. A written consent was obtained from all patients. The subjects were aged between 18 and 35 years. This was a prospective cross-sectional study. Thyroid glands were scanned using a 2-dimensional ultrasound machine with a 7.5 MHz transducer; model Siemens Sonoline Prima which was made in Japan for Siemens Medical System Incorporated, ultrasound Group, Issaquah, WA, 98029-7002, USA. Results: The study revealed no incidence of pyramidal lobe and agenesis of the thyroid isthmus in the study population. Conclusion: This study has clearly demonstrated no incidence of pyramidal lobe and agenesis of the thyroid isthmus in subjects resident in Nnewi, Nigeria.

Parasitic thyroid nodules in patient with nontoxic multinodular goiter: a case report

Introduction

The presence of benign thyroid tissue that is located on the side of the neck is extremely rare and not related to the development of the thyroid, and it is difficult to differentiate it from thyroid carcinoma metastasis.

The parasitic thyroid nodule occurs when thyroid tissue located in the lateral neck has no relationship or association with the lymph nodes, and may be defined as a thyroid nodule entirely separate from the thyroid or attached to it by a narrow pedicle, presenting the same histology and in the same facial plane as the thyroid, and should not be associated with lymph nodes.

Case presentation

A 40-year-old Brazilian man without significant past medical history presented with a large volume multinodular thyroid goiter that caused deformity and symptoms suggestive of cervical spine compression. He underwent a total thyroidectomy. His thyroid function was normal. Ultrasonography showed a heterogeneous thyroid nodule measuring 3.7cm to the right from midline and 3.3cm to the left from midline that was associated with two nodules in the left submandibular area measuring 1.43cm and 1.52cm.

Fine needle aspiration confirmed the benign nature of the gland and thyroid tissue etiology of the two submandibular nodules, located in level II of the neck. Since the ectopic thyroid tissue in his lateral neck was suggestive of metastasis of occult primary thyroid carcinoma, the patient underwent a total thyroidectomy plus a left modified radical neck dissection with preservation of level I. The diagnosis of multinodular goiter associated with two parasitic thyroid nodules was confirmed by immunohistochemistry.

Conclusions

We conclude that the parasitic thyroid nodule should be included in the differential diagnosis of lateral neck masses. The diagnosis and differentiation of these nodules from metastatic adenopathies of differentiated thyroid carcinoma has important therapeutic and prognostic implications, and can lead to avoidance of unnecessary surgeries.

An accessory thyroid gland that presented tumor-like images

A 26-year-old woman presented with right breast pain and itching. Incidentally, a firm, non-tender, movable mass (3 cm in diameter) located in the lower right part of the neck was identified by palpation. Ultrasonography revealed a clearly demarcated dumbbell-shaped mass with homogenous hypo- (cranial side) and hyper-echogenicity (caudal side) compared with the thyroid gland. Computed tomography scan and magnetic resonance imaging presented images that were different from thyroid gland substance. The right thyroid lobe was strongly compressed by the mass. Hyperparathyroidism was ruled out by laboratory testing. The patient solicited resection of the mass despite recommendations for core needle biopsy, and it was removed surgically. The mass was surrounded by a thin capsule and was not connected with the thyroid gland. Pathological examinations revealed normal thyroid gland tissue. The final diagnosis was an accessory thyroid gland. Accessory thyroid glands should be considered as a possible diagnosis when nodules around the main thyroid gland are encountered.

The pyramidal lobe: clinical anatomy and its importance in thyroid surgery

The pyramidal lobe could be a source of pitfalls in thyroidectomy, due to its frequency but unreliable preoperative diagnosis on scintigraphic images. Special attention has to be paid to the pyramidal lobe to avoid leavings of residual tissue when complete removal of the thyroid is indicated. Sixty cadaveric specimens were examined with special emphasis to the topographical anatomy and expansion of the pyramidal lobe. A pyramidal lobe was found to be present in 55% of the cadavers (32/58). It was found more frequently in men than in women. In men the median length was 14 mm and in women 29 mm. An accessory thyroid gland was present in one specimen, in four cases the isthmus was missing. The pyramidal lobe branched off more frequently from the left part of the isthmus (16) than from the right (7) or the midline (9). In two cases it originated from the left lobe. Additionally 23 scintigraphic images were analyzed to evaluate the visualization of a pyramidal lobe. Only three of them showed enlargements of the isthmus that could be taken as a pyramidal lobe. Due to its frequency the pyramidal lobe should be regarded as a normal component of the thyroid. It is not reliably diagnosed by scintigraphic imaging because scintigraphy can only give functional information but not morphological one. Therefore the anterior cervical region has to be investigated very carefully during operation in order not to leave residual thyroid tissue in total thyroidectomy.

Thyroid function and morphology in patients affected by Williams syndrome

OBJECTIVE

To evaluate the prevalence of abnormalities of thyroid function and morphology in a cohort of patients with Williams syndrome (WS).

METHODS

Serum concentrations of free-T3, free-T4, TSH, thyroperoxidase antibodies (TPOA) and thyroglobulin antibodies (TgA), as well as ultrasonographic data, of 20 patients with WS (12 females and eight males), aged 1.7-34.9 years, were evaluated.

RESULTS

Three cases (15%) of subclinical hypothyroidism were identified. Overt hypothyroidism was diagnosed in two cases (10%). Thyroid antibodies were negative in all patients. Fourteen patients (70%) showed thyroid hypoplasia involving the entire gland. In these patients, the left thyroid lobe appeared usually, but not significantly, reduced compared with the right thyroid lobe. One patient (5%) showed thyroid hemiagenesis. Only five patients (25%) showed a thyroid with normal volume, and of these five, one patient showed marked thyroid hypoplasia of the left lobe. In all WS patients with diagnosis of subclinical or overt hypothyroidism, thyroid hypoplasia was detected. No cases of subclinical or overt hypothyroidism were found in WS with normal thyroid volume.

CONCLUSIONS

This study confirms the presence of alterations of thyroid function in WS and also suggests the frequent occurrence of abnormalities of thyroid morphology in these patients. Patients with WS should be monitored for thyroid function and a thyroid ultrasound screening should be considered, especially in those patients with changes in thyroid function.