Detection of medullary carcinoma of thyroid, with liver metastasis, using 99mTc DMSA(V) scintigraphy.

S Shikare, K Bashir, PS Menon, RD Bapat, GH Tilve 
 Dept of Nuclear Medicine, K E M Hospital, Parel, Bombay.

Correspondence Address:
S Shikare
Dept of Nuclear Medicine, K E M Hospital, Parel, Bombay.

Full Text

::   Introduction

Medullary carcinoma of the thyroid is an uncommon tumour arising from the parafollicular cells of the thyroid[1]. The major sites of distant metastasis of this tumour are lung, liver and bone 99m Tc labelled pentavalent DMSA has been shown to be taken Op by the primary and recurrent tumour, along with its metastasis, with sensitivity variably reported as 65 to 88%[2]. We present the case report of a patient who had medullary carcinoma of the thyroid with metastasis in the liver.

::   Case report

A sixty-year-old female referred for thyroid and liver scintigraphy had a clinical history of progressive swelling in the neck along with hepatomegaly. Biochemical, thyroid function tests were normal but serum calcitonin levels were raised.

Thyroid scan done with 99m Tc pertechnetate revealed a large cold area in the centre of the enlarged right lobe [Figure:1] and 99m Tc phytate liver scan showed a large cold area in the right lobe of liver posterolaterally [Figure:2].

Subsequent whole body scan with 99m Tc DMSA (V) showed (1) avid tracer uptake in the right lobe with central area of decreased tracer uptake, (2) Intense focal tracer accumulation in the right lobe of liver posterolaterally, correspondingly with the lesion seen on the routine liver scan [Figure:3]. No skeletal metastases were seen.

Aspiration cytology from the thyroid and the liver showed medullary carcinoma of thyroid and its metastasis in the liver. Subsequently, the patient underwent thyroidectomy and histopathology confirmed the diagnosis of medullary carcinoma of thyroid.

::   Discussion

In patients of medullary carcinoma of the thyroid (a) 99m Tc pertechnetate imaging of the thyroid demonstrates an area of reduced uptake corresponding to the site of the nodule that is solid on ultrasound. (b) liverspleen scans demonstrate areas of reduced tracer uptake in the sites of metastasis and (c) bone metastasis are picked up as areas of increased tracer uptake on bone scan. However, all these findings are non-specific as other pathological states can give rise to such scan findings.

99m Tc pentavalent DMSA is selectively taken up into sites of primary, recurrent and metastatic medullary carcinoma of the thyroid. Due to its remarkably low, nonspecific uptake in organs such as the liver and bone marrow, identification of liver and bone metastases is facilitated[3]. This greatly increases the specificity of the diagnosis of medullary carcinoma of thyroid in suspected primary, recurrent and metastatic sites. Thus this imaging agent is now contributing significantly to patient management with its ability to define both local soft tissue recurrence and distant metastasis.

::   Acknowledgment

We thank the Dean, Seth GS Medical College and King Edward Memorial Hospital for allowing us to publish these data.

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