JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
Pediatric Polycystic Thyroid: Rare Innocent Finding or Harbringer of Disease?
Eileen Báez, MD, Marie Haymon, MD, Liladhar Kashyap, MD, Laurie Finger, APRN, Stuart Chalew, MD
Background: Ultrasound identificationofmultiple small thyroid cysts inadults, so called polycystic thyroid (PCT) disease has been associated with overt hypothyroidism. The significance of PCT in childhood is unclear.
Methods: We report ultrasound, clinical , biochemical and follow-up data on eight patients (four males and four females, mean age 13.2 years) found to have PCT.
Results: All patients on ultrasound had increased thyroid gland size, with multiple small cysts (<6 mm) throughout the gland, but most often at the periphery, without evidence of vascular changes or echogenicity. With the exception of one patient with initial slight increase of TSH, all patients had normal free T4, TSH, and negative thyroid auto-antibodies. No progression was noted on follow up. Conclusions: Pediatric PCT is characterized by a benign, asymptomatic presentation . However, as most patients with overt hypothyroidism and PCT have been adults, a longer period of clinical observation in pediatric patients is prudent to ensure that deterioration of thyroid function does not occur over time.
INTRODUCTION Sophisticated high resolution imaging techniques have become widely available and frequently used. With increased numbers of imaging procedures being done for various indications, there has been a corresponding increased discovery of incidental findings of uncertain pathologic significance that often pose dilemmas for diagnosis, therapy and follow-up. In 2010, Avula et al. in Canada reviewed 256 pediatric neck ultrasounds performed for non-thyroidal indications in which the entire thyroid was visible. They found that 52 of these patients had incidental thyroid abnormalities, including 25 who had multiple small cysts (<4 mm).¹ The clinical and biochemical thyroid status of these patients was not reported. This study suggests that multiple, small, scattered thyroid cysts may be a common, incidental and asymptomatic finding in the pediatric thyroid. In contrast, Kubota et al. in Japan reported that six middle- aged and elderly adult patients with small scattered thyroid cysts on ultrasound had thyroid auto-antibody negative hypothyroidism.²,³ Kubota et al. termed the condition“polycystic thyroid disease.”²,³ In a further follow-up study of Japanese patients with antibody-negative hypothyroidism, polycystic thyroid (PCT) on ultrasound was associated with 7.8% of cases with overt hypothyroidism and 7.7% of cases of subclinical hypothyroidism.¹ Thus multiple small cysts of the thyroid appears be a risk factor for hypothyroidism particularly in adults. More recently Naranjo et al. reported two Spanish children who were found to have thyroid antibody-negative, subclinical hypothyroidism incidentally discovered in the workup for short
stature and monitoring of lithium therapy. These two patients both had PCT on ultrasound.⁴ Thus, the clinical significance of PCT as a marker of hypothyroidism in children is unclear. In this report we wish to present and discuss eight pediatric patients with PCT along with their physical and laboratory findings, as well as the role of clinical follow up in this condition. CLINICAL REPORT Patient endocrine evaluation and thyroid ultrasonography was performed at the Children’s Hospital of New Orleans, Louisiana. Ultrasoundswereperformedwith aGE LOGIQE9device andused ML6/15 linear transducer.Thevolumeof each lobewas calculated from the measurements of the depth (d), the width (w), and the length (l) of each lobe by the formula: Volume (ml) = 0.479 x d x w x l (cm)[5, 6]. The thyroid volume was the sum of the volumes of both lobes. The volume of the isthmus was not included. TSH and FreeT4were performed in the clinical laboratory of the Children’s Hospital using an Immunochromatographic Membrane Assay (ICMA) and Electrochemiluminescence immunoassay (ECLIA), respectively. Anti-TPO (Antithyroperoxidase )and Anti- TG(Antithyroglobulin) antibodies were performed at Esoterix Endocrine using Chemiluminescense and ICMA, respectively. The intra-assay coefficient of variation was 4.2-5.19% for TSH and 3.29-5.01% for FT4. The inter-assay coefficient of variation was 7-12.7% for TSH and 4.7-5.8% for FT4. Patients treated with thyroxine received starting doses based on literature recommended (6-12 year- 4-5 mcg/kg ; > 12 year 2-3 mcg/kg ) and titratedbased on subsequent fT4 andTSHby their attending.
114 La State Med Soc VOL 170 JULY/AUG 2018
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