CASE N°43 – Medullary thyroid carcinoma
Single thyroid nodule; Ultrasound: hypocaptation; scintigraphy: cold; serum calcitonin: 40
cytological speciemen: thyroid fine-needle aspiration
Aggregates composed by cells in part with eccentric nucleus and finely granular chromatin, mixed with red blood cells and scant colloid.
The cytological findings is attributable to a neuroendocrine tumor; this figure and the value of calcitonin, suggest medullary carcinoma of the thyroid.
histological speciemen: thyroid, excision
Medullary carcinoma of the thyroid.
Tumor growth fraction (MIB1): <5%.
The lesion appear to be limited to the context of the thyroid parenchyma.
Absence permeation of tumor vessels.
Unlike most other carcinomas arising from the follicular cell of
the thyroid, medullary thyroid carcinoma (MTC) is a malignancy
with neuroendocrine features, derived from the parafollicular C
cell, which is of ectodermal neural crest origin. In most studies,
MTC represents 3–12% of thyroid cancers, the majority of which
are sporadic. However, in approximately 25–30% of cases, MTC is
inherited, and is associated with one of three familial syndromes:
multiple endocrine neoplasia (MEN) syndrome type 2A, MEN
type 2B, and familial MTC.
Major cytologic features of medullary carcinoma are as follows:
• Uniform population of single cells
• “Salt-and-pepper” chromatin
• Background amyloid
• Common cell types
For all types of MTC, the average 5-year survival rate is 78–92%
and the 10-year survival rate is 61–75%. Overall, the most important
prognostic factor for MTC is disease stage at presentation,
and the primary treatment modality for MTC is surgery. Because
the treatment of MTC involves complex decision making and
surgical intervention (e.g., total thyroidectomy with or without
neck dissection), an accurate FNA diagnosis is essential to avoid
multiple unnecessary surgeries.
MTC frequently metastasizes at an early stage to regional lymph
nodes in the central and lateral neck as well as to the superior
mediastinum. For this reason, some form of lymph node dissection
is usually performed in addition to total thyroidectomy. At some
institutions, patients receive a central neck and upper mediastinal
lymph node dissection, and for patients with palpable nodal disease,
either ipsilateral or bilateral modified radical neck dissection
(MRND) is performed. Postoperatively, calcitonin and CEA serum
levels are routinely monitored to help identify those patients with
recurrent or metastatic disease.
Douglas P.Clark, William C.Faquin. Thyroid Cytopathology (second edition). Essential in Cytopathology Series Editor Dorothy L.Rosenthal. Springer, 151-166