A 73-year-old man was referred to the general medical clinic with a 3-year history of shortness of breath and wheeze. During assessment he commented that over the same period he had also had intermittent sweats, flushing and redness of the face especially after eating and taking red wine. Echocardiogram and urinary 24-h 5-hydroxyindoleacetic acid (5-HIAA) were arranged. Surprisingly two of three urinary 24-h urinary 5-HIAA were positive (43 and 47.5 μmol/24 h and 30 μmol/24 h, NR 636 μmol/24 h).
Given the clinical suspicion of carcinoid syndrome an octreotide scan was performed in anticipation of finding an intestinal lesion. Unusually this demonstrated avid tracer uptake in the neck corresponding to a 3×4 cm mass in the thyroid gland on computerised tomography. He was referred to the endocrine services for further evaluation.
MIBG SPECT confirmed avid uptake in the right lobe of the thyroid gland. Neither imaging modalities showed associated lymphadenopathy. The diagnosis of a neuroendocirne thyroid tumour was made and ultrasound guided fine-needle aspiration cytology of the thyroid mass was performed. Initial cytology indicated a follicular lesion grade Thy3. Repeat FNAC was more suggestive of a medullary neoplasm. Core thyroid biopsy confirmed a medullary carcinoma of the thyroid which was calcitonin positive. MRI of the adrenals and serum calcium were normal making MEN2 unlikely.
The patient was commenced on lanreotide 60 mg monthly and underwent total thyroidectomy and neck dissection. Histology showed a well-circumscribed medullary thyroid carcinoma. He made an excellent post-operative recovery with total resolution of his symptoms of flushing. Post-operative urine collections for 5-HIAA were normal, as were calcitonin and chromogranin A levels. A follow-up octreotide scan 4 months after surgery showed no avid uptake in the neck.
Although carcinoid most commonly is derived from an intestinal tumour source it is important to note that medullary thyroid carcinoma is also a rare source.