Giant Hyalinizing Trabecular Carcinoma of the Thyroid Gland in a 20-Years Old Male Patient
Michael S Papageorgiou
Department of Endocrine Surgeon, American Medical Center, Cyprus
Submission: November 08, 2018;Published: November 21, 2018
*Corresponding author: Michael S Papageorgiou, Department of Endocrine Surgeon, American Medical Center, Nicosia, Cyprus
How to cite this article: Michael S P . Giant Hyalinizing Trabecular Carcinoma of the Thyroid Gland in a 20-Years Old Male Patient. J Endocrinol
Thyroid Res. 2018; 4(1): 555626. DOI:10.19080/JETR.2018.04.555626
Hyalinizing trabecular tumors (HTT) are a rare and relatively young entity in thyroid pathology. They are tumors that are frequently mistaken for papillary or medullary carcinomas and they are characterized by the trabecular growth pattern and hyalinizing stroma. Most of them are benign, but there are few reports of malignant behavior (capsular invasion, metastases etc.) We report a case of a 20-years-old male with a 6,5cm left lobe thyroid nodule, who was treated with total thyroidectomy and level VI lymph nodes dissection. The final pathology diagnosed the tumor as a Hyalinizing trabecular carcinoma (HTC).
Hyalinizing trabecular tumors were first described in 1987 by Carney et al.  who reported a series of 11 cases that they were categorized as HTTs, while the distinctive features of these tumors were the trabecular cell growth pattern and the hyalinizing stroma . Ever since, it was believed that these tumors were completely benign, with only a handful of exceptions. To add in the controversy, in everyday practice, these tumors were often misdiagnosed as papillary carcinomas or medullary carcinomas. To answer this controversy, World Health Organization (WHO) classified these tumors as Hyalinizing trabecular tumors (HTTs), thus including adenomas and carcinomas in a mixed category . HTTs affect mainly the female population (male to female ratio 1:6) [2,3]. Although cases were reported between 20 and 80 years old, the mean age of diagnosis is 50,5 years-old. We report a rare case of a 20-years-old male with a gigantic (6,5cm) Hyalinizing trabecular carcinoma (HTC). Diagnosis and treatment are presented, and some key points of the literature are discussed.
A 20-years-old male patient presented to the Outpatient Department with a large cervical mass, extending predominantly to the left side. Family members stated that he had the mass for many years (at least 4 years), although not as big as it was at present. The patient had no previous medical conditions and there was not any family history of thyroid diseases. An ultrasound and a CT scan demonstrated a large nodule of the left thyroid lobe, measuring 9x6,5x5cm and two smaller cystic nodules in the right lobe. Lymph nodes ultrasonic investigation demonstrated mildly enlarged level VI nodes, with no evidence of infiltration, while an FNA of the large mass showed a Thy-4 neoplasm, suspicious for papillary carcinoma. Considering the size of the tumor and the evidence of lymph nodes participation, a total thyroidectomy with level VI lymph nodes dissection was proposed and finally performed. In surgery, a neuromonitoring device was used and both recurrent laryngeal nerves and 4 parathyroid glands were identified and saved. The postoperative course was uneventful, and the patient was discharged on the first postoperative day, with calcium supplements and thyroxin tablets. Final pathology stated that the large mass was a Hyalinizing trabecular carcinoma. Detailed description stated that the tumor cells were arranged in elongated trabeculae and in one point the tumor extended through the adjacent capsule in an invasive growth pattern. Immunotoxins showed positivity for PAX-8 and TTF-1, while chromogranin and calcitonin were negative. Ten (10) lymph nodes that were removed, proved to be negative for malignancy. Patient was referred for RAI treatment and it was performed with any indications of persistent or recurrent disease (Tg<0,1 ng/ml with TSH 78,3 μIU/ml). Afterwards, the patient was under close follow-up, and 2 years since, he is free of any indications of recurrence.
Hyalinizing trabecular tumors (HTT) are a new entity in thyroid pathology. The tumors show some mutual characteristics with papillary carcinomas (RET/PTC rearrangements) thus leading some experts believe that they are merely a subtype of papillary carcinomas instead of a distinct category . Other cases are mistaken as medullary carcinomas, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) or even as paragangliomas . Diagnosis is made as in every other thyroid nodule. Ultrasonography features are general and usually include hypo echogenicity or marked hypo echogenicity in the
absence of other suspicious features (calcifications etc.) FNA results
are often misleading as well. A previous study showed that
only 8% of HTTs were diagnosed preoperatively with FNA and an
additional 6% was only suspected. Most of the times FNA reports
indicate a possibility or even a certainty for papillary carcinoma
(55%-60%) [5,6]. In our case, the FNA report was highly suspicious
for papillary carcinoma, with a possibility of 60%-75%. To
add up to the controversy, most authors considered HTTs to be
always benign. In the following years though, cases were reported
with malignant behavior, such as lymph nodes and pulmonary
metastases, or detection of BRAF mutations [7-9]. Unfortunately,
these few cases cannot be surely distinguished by FNA, core
biopsy, or even frozen section during surgery (only 53% could
be diagnosed correctly) . In our patient, we performed a total
thyroidectomy with central compartment lymph nodes dissection,
based on the high suspicious for PTC and the possible
lymph nodes participation. Treatment is also an issue for debate.
Since the majority of HTTs are benign, a lobectomy is the treatment
of choice for these lesions. But taking in concern that even
a few cases have a malignant potential and can lead to metastatic
disease, a completion thyroidectomy and RAI treatment must be
performed in these patients [2,10,11]. Our case presented in this
report, is a very rare case of an HTC. The patient was male, in a
young age, with a very large tumor. Malignancy was established
by a microscopic invasion of the capsule by the tumor cells. Although
the size of the tumor was large, lymph nodes removed
were negative for infiltration and the postoperative course indicates
a relatively low malignant potential.
In conclusion, Hyalinizing trabecular tumors represent a
relatively new, rare and understudied part of thyroid pathology.
Most of the knowledge acquired is by case reports or a few small
case series in the literature. In our opinion, large multicentral
studies should be designed, in order to address these following
• What is the true malignant potential of these tumors?
• How can we increase our chances for a correct preoperative diagnosis, in order to avoid unnecessary total thyroidectomies
and identify only the malignant ones?
• Is a lobectomy the preferred treatment in these tumors
from start? What should be our surgical strategy for these
patients? Is there a need for prophylactic lymph nodes dissection
if there is a possibility or certainty for malignancy?
• Is RAI treatment needed in these patients? And if yes,
what is the survival rate in malignant cases?