Clinico-pathological and prognostic findings on 27 cases of medullary thyroid carcinoma.

Abstract

Introduction: Medullary thyroid carcinoma is a rare tumor accounting for less than 10% of thyroid neoplasm. This tumor is characterized by
important histological polymorphism which makes morphological diagnosis difficult and immunohistochemical study often necessary.

Objective: We aim to perform a retrospective review of clinical and pathological characteristics of medullary carcinoma. We will discuss the place
of immunohistochemistry in the positive diagnosis and as a prognostic factor.

Methods: patients with thyroid medullary carcinoma diagnosed in department of pathology at carcinologic institute between 1998 and 2013 were
retrospectively included. Clinic, radiologic and prognostic variables were assessed. Slides were reviewed for all the patients with confirmed
tumors.

Results: Twenty-seven patients with CMT were identified. The average age was 55 years with predominance of males. The average consultation
time was 16 months. The most common presentation symptom was a cervical lymph node.
Total thyroidectomy was performed in 23 patients. Tumor was nodular and unique in 22 cases. The average size was 2.1 cm. CMT was of mixed
type containing both medullary and papillary compound in four cases. Amyloid substance was present and abundant in 21cases. Positive staining
for calcitonin was observed in 16 cases. Distant metastasis or metastatic lymph nodes was observed in eight cases with an average period of
42 months. Radiotherapy was performed in fifteen cases and two patients received chemotherapy.

Conclusion: In the absence of amyloid deposits, immunohistochemical staining with calcitonin is useful to confirm the diagnosis. The prognosis
of this entity is more pejorative than papillary thyroid carcinoma.