JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
Endocrinology for evaluation of a goiter. She was otherwise well and without symptoms of thyroid disease. Physical examination was significant for a body mass index (BMI) >97th percentile, she had prominent nuchal fat, and no distinct goiter or thyroid nodules.
does not typically lead to hypothyroidism in healthy individuals without pre-existing thyroid disease.⁸
Kubota et al. obtained histopathological samples from their patients with PCT disease and compared them to patients with multinodular goiter.³ PCT disease was characterized by enlarged colloid containing follicles of variable sizes, usually up to 5 mm.³ The large follicles corresponded to the cysts that were detected by ultrasonography. The follicles were cuboidal and normal appearing. There were no findings of an aggregation of small follicles, papillary projection or degenerative changes in the follicles as would be found in multinodular goiters. Thus adult PCT disease has distinct ultrasound and histopathologic characteristics. When comparing ultrasound findings, multinodular goiters are often described as being heterogeneous, without well defined nodules or multiple nodules interspersed throughout a normal appearing gland.⁹ Areas of hemorrhage, necrosis, and calcifications were often seen. In contrast, auto-immune thyroiditis presents withmarked glandular hypoechogenicity, usually non-homogenous, as well as changes in vascularity on Doppler flow.¹⁰, ¹¹ In a separate small case series of Japanese adults, the ultrasound finding of a localized area of multiple small cysts within the thyroid coalescing to give a honeycomb appearance was associated with papillary thyroid carcinoma.¹² This is in contrast to the presentation of PCT where cysts are scattered throughout the gland rather than localized to a discrete area. Unlike the Japanese adult literature, PCT has not been classified as a distinct condition in children. However, in a survey of imaging studies of the neck performed for non-thyroid indications in Canada, Avula et al. reported incidental thyroid abnormalities in 52 scans of 287 ultrasounds where the entire thyroidwas visible. Multiple scattered small thyroid cysts, similar to what was termed PCT by Kubota et al. accounted for 48% or 25 of the 52 abnormal thyroids.¹ Thus occurrence of pediatric PCT might be as high 8.7% (25 out of 287 scans). Avula did not comment on the clinical or laboratory status of the patients with abnormal thyroids. Thus the clinical significance of PCT from this report was left unclear. More recently, two childrenwith ultrasound findings of PCTwere reported from Spain.⁴ These patients were initially identified with antibody-negative, “subclinical hypothyroidism ” (fT4 and TSH not reported in the article) in the course of evaluation for short stature in one, and for surveillance of lithium therapy for bipolar disorder in the other. Neither of these patients had goiters. Assuming these patients both had normal fT4 with increased TSH may indicate an initial deterioration in thyroid function, which is similar to the initial findings in patient 2 who presented with a slight elevation of TSH with normal total thyroxine levels. Unfortunately the clinical course of patient 2 is unknown as he was lost to follow up. Our other patients did not have initial abnormalities of free T4 or TSH or exhibit ultrasound or biochemical progression of disease.
PATIENT 7
Patient was a 14 year old female referred to Endocrinology for repeated stress fractures of foot. She was without symptoms of thyroid disease. Mother has Hashimoto’s thyroiditis. Physical examination was significant for a BMI >97th percentile and a small, soft palpable goiter. This patient was recently evaluated and has not had follow-up for more than a few months.
PATIENT 8
Patient is a 16 year and 5 month old female referred for evaluation of goiter discovered incidentally during a routine annual visit. She had no symptoms of thyroid dysfunction and no family history of thyroid disease. Thyroid functions were normal, antithyroglobulin and antimicrosomal antibodies were negative.
DISCUSSION
We report clinical findings from eight pediatric patients (7-16 years of age) who had multiple small cysts scattered throughout an enlarged thyroid gland. This is the largest series of pediatric cases correlating ultrasound, clinical, biochemical findings, and preliminary follow up. In general most of the scans from our patients were characterized by slight thyroid gland enlargement withmultiple scattered (but most often at the periphery) thyroid cysts without evidence of vascular changes or echogenicity. The cysts were of small size, < 6mm. Thyroid auto-antibodies were negative in all patients. Our pediatric patients were referred for endocrine evaluation after having been incidentally discovered to have a goiter or incidentally found to have a thyroid abnormality by imaging for a non-thyroid indication. These ultrasound changes in our pediatric patients were similar to those previously described in a series of Japanese adults, and termed “polycystic thyroid disease” by Kubota et al.2,3,7 The Japanese patients were of much older age (60-81 years) and PCT was associated with 7.8% of cases with overt and 7.7% of cases of subclinical antibody-negative hypothyroidism.¹ Many adult patients with PCT who were initially euthyroid, eventually developed hypothyroidism.² Kubota et al. suspected that hypothyroidism in these patients developed secondary to cyst impingement on functional thyroid tissue combined with high dietary iodine intake, causinganimpairedWolff–Chaikoffeffect.²,⁷ In a small number of the Japanese patients with a high dietary intake of iodine, it was found that dietary iodine restriction in the hypothyroid patients led to a return to the euthyroid state.⁷ The authors speculated that the presence of multiple cysts was a factor in the development of hypothyroidism, as iodine excess
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